MOCVD

In the field of packaging, coatings are commonly applied on containers to avoid interactions between them and their content. For glass bottles, application of a thin film prevents interactions with the phase in contact and consequently the alteration of surface properties of the latter. In this article, we propose an innovative way to apply amorphous alumina coatings on glass bottles by metalorganic chemical vapor deposition from aluminum tri-isopropoxide. A numerical model, using the Computational Fluid Dynamics code FLUENT, has been developed to calculate local profiles of gas flow, temperature, concentration and deposition rates into the reactor. The sub-micrometric alumina films have been deposited at reduced pressure between 480°C and 670°C. Uniform thickness profiles have been determined on cross sections over the length of the bottle and have been successfully simulated. Strongly improved hydrolytic resistance with regard to the uncoated bottles reveals the excellent performa...

The annealing condition dependence of the electrical and optical properties in C-doped InGaAs lattice-matched to InP is investigated in detail. It is revealed that hole concentration increases with annealing time at annealing temperatures between 450°C and 550°C due to hydrogen removal from epilayers. The annealing time for obtaining the maximam hole concentration is shown to become shorter with higher annealing temperature. It is also found that C acceptors are deactivated by annealing at 550°C for more than 5 min, resulting in a decrease of hole concentration, mobility and photoluminescense intensity. These deteriorations in both the electrical and optical quality of C-doped InGaAs might be caused by the transformation of C acceptors to C donors (on group-III sites) or interstitial C atoms. The optimum annealing condition was applied for the fabrication of InP/InGaAs heterojunction bipolar transistors, and the good characteristics are successfully demonstrated.

We report design, growth, and characterization of midwavelength infrared nBn photodetectors based on a type-II InAs/InAs1-xSbx superlattice
on a GaSb substrate grown by metal-organic chemical vapor deposition. An InAs/AlAs1-ySby/InAs/InAs1-xSbx superlattice design was
used as the large bandgap electron barrier in the photodetectors. At 150 K, the photodetector exhibits a peak responsivity of 1.23 A/W,
corresponding to a quantum efficiency of 41% at an applied bias voltage of 100mV under front-side illumination, with a 50% cut-off wavelength
of 4.6 um.

Novel tungsten precursors, WH 2 (iPrCp) 2 and WH 2 (EtCp) 2 , with attractive thermal properties are introduced for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of tungsten containing films. Their thermal behavior has been assessed using a vapor pressure measurement set-up and a thermal gravimetric apparatus (TG/DSC/DTA). Thin films of WC x and WN x C y were deposited depending on the reactant used. Kinetics of the surface reaction using WH 2 (iPrCp) 2 precursor has been evaluated carrying out MOCVD at low temperature ranging 350°C to 400°C. On-line QMS analysis of the deposition process was used to characterize the precursor decomposition pathway. Physical and electrical properties of the films were evaluated by X-Ray Reflectrometry (XRR), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Secondary Ions Mass Spectrometry (SIMS), and four-point probe. Oxygen containing, porous and amorphous WC x (x ∼ 0.5) and WN x C y (x ∼ 0.4, y ∼ 0.2) thin films have been achieved.

Niobium nitride thin films are deposited on 2 00 silicon (100) wafers using a modified industrial metal-organic (MO) CVD reactor of the type AIX-200RF, starting from tert-butylamido-tris-(diethylamido)-niobium (TBTDEN) and ammonia. Films of thicknesses 50-200 nm are deposited at temperatures ranging from 400 8C to 800 8C under reactor pressures of 1 and 5 mbar using various ammonia flow rates, and are characterized by the use of complementary techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), secondary neutral mass spectrometry (SNMS), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), and electrical measurements. Films deposited above 450 8C consist of the cubic d-NbN phase, apart from the presence of Nb-O and Nb-O-N species predominantly in the outermost film regions. The lowest specific resistivities, determined by four point probe measurements, are in the range 500-600 mV cm. A NbN/SiO 2 /p-Si gate stack is fabricated using the grown niobium nitride films. From the capacitance-voltage (C-V)-curves, flatband voltages are extracted which, when plotted against SiO 2 -insulator thickness, yield a work function of 4.72 eV for asdeposited films.

We have fabricated and investigated several types of GaN MOSFETs with normally-off operation. The recessed-gate GaN MOSFET is preferred for normally-off operation, because the threshold voltage (Vth) of the device can be easily controlled, but it suffers from relatively modest current drivability which must be improved by adopting appropriate device structure and/or process. Enhanced performances have been achieved in this work by combining the recessed-gate technology with additional processes, such as: the post-recess tetramethylammonium hydroxide (TMAH) treatment to remove the plasma damage, the post-deposition annealing of gate oxide to decrease the gate leakage current, the re-growth of n+ GaN layer for source/drain to improve the access resistance and Vth uniformity, the stress control technology to achieve extremely high 2-D electron-gas density (2DEG) on source/drain and decrease the series resistance, and the use of the p-GaN back-barrier to decrease the buffer leakage current. The GaN-based FinFET with very narrow fin was also investigated as a possible candidate for high performance normally-off GaN MOSFETs. Int. J. Hi. Spe. Ele. Syst. 2012.21. Downloaded from www.worldscientific.com by 59.24.70.102 on 02/16/13. For personal use only. Int. J. Hi. Spe. Ele. Syst. 2012.21. Downloaded from www.worldscientific.com by 59.24.70.102 on 02/16/13. For personal use only.

AlGaN/GaN high electron mobility transistor (HEMT) was grown on silicon carbide substrate by metalorganic chemical vapor deposition technique. The AlGaN/GaN structure was optimized by tuning the growth conditions such as AlN buffer thickness, and the Al composition and thickness of AlGaN barrier layer. As a result, the X-ray rocking curve widths were 277 arcsec and 324 arcsec for the GaN (002) and (102) planes, respectively, indicating a high crystalline quality. Hall measurement showed that the AlGaN/GaN structure has a high electron mobility of 1840 (cm 2 /V-s) and a sheet electron concentration of 9.85 x10 12 cm-2 . Besides, HEMT device with sub-micron gate-length (0.7 m) was also successfully fabricated. DC measurement showed that the HEMT device has a saturated current of 800 mA/mm, a transconductance of 257 mS/mm and an off-state breakdown voltage larger than 100 V. For RF performance, the device has achieved an output power density (P out ), gain, and power added efficiency (PAE) of 7 W/mm, 23.5 dB and 61.7%, respectively, measured at 2 GHz frequency. On the other hand, the RF performance measured at 8 GHz showed that the device could achieve P out , gain and PAE of 5.01 W/mm, 14.9 dB and 26.23% respectively.

Parameters of the crystal lattice AFM Atomic force microscopy CCD Charge-coupled device CL Cathodoluminescence EDX Energy-dispersive X-ray spectroscopy ELO Epitaxial lateral overgrowth FWHM Full-width at half-maximum HAADF High-angle annular dark field LED Light emitting diode MBE Molecular beam epitaxy MOVPE Metalorganic vapor phase epitaxy MQW Multi-quantum well NBE Near band edge NSAG Nano-selective area growth(/grown) SAG Selective area growth(/grown) SEM Scanning electron microscopy Si(111) The (111) plane of silicon STEM Scanning transmission electron microscopy UV Ultraviolet XRD X-ray diffraction vii SUMMARY We developed and evaluated NSAG techniques for Group III-Nitrides as a way to mitigate the various difficulties with this material system (high defect density, threading dislocations, phase separation and graining, etc.), to bring these material systems to the nanoscale, and to allow the use of inexpensive silicon substrates. To that end, we used optimized NSAG of GaN, InGaN, AlGaN, and BGaN grown on GaN/Sapphire and AlN/Si(111) templates, evaluating the effectiveness of our NSAG techniques on each template by comparing our results to those obtained from planar (non-NSAG) growth. We also investigated the engineering of microtemplates by coalescing NSAG GaN structures and comparing surface properties and subsequent epilayer growth to that of normal planarly grown GaN. Across the board, NSAG was selective and, when compared to planar growth, consistently resulted in higher quality material with fewer dislocations. NSAG of GaN on AlN/Si(111) resulted in defect-free nanopyramids, 90% of which were single crystal. By coalescing nanostructures into a microtemplate, we produced an InGaN top layer with 7 times the optical emission intensity as InGaN grown simultaneously on non-NSAG planar GaN. NSAG InGaN nanopyramids grown on GaN/Sapphire templates were used to make PIN-based solar cells that produced current 3 orders of magnitude greater than their planar counterparts, and which had 20 times greater IV ratios at ±1 V. We then leveraged this newly-won know-how with our previous success growing NSAG GaN on AlN/Si(111) to produce InGaN nanopyramids on AlN/Si with no defect band and viii 50% stronger luminescence than in 2D growth. These nanopyramids were highly uniform, single-crystal, dislocation-free, and free from phase clustering effects and other nonuniformities found in planar growth. With additional effort, we achieved a maximum InN composition of 33%, with NSAG material showing four times better emission characteristics than planar material on the same substrate. Additionally, we found that mask margin affected InN composition and therefore emission wavelength of our nanopyramids, and that by using different mask geometries on the same template, we can create single-growth-step multi-color micropixels. In our most current iteration, we produced both green and red-emitting material in one growth step.

A new method for integration of optical mode converters with InP-based photonic integrated circuits is described and demonstrated. The mode converter is integrated to a Sampled Grating DBR (SG-DBR) laser to demonstrate integration and to facilitate accurate fiber-coupling loss measurements. The entire fabrication process requires a single MOCVD regrowth, making it compatible with low-cost integration with other photonic components. The mode converter utilizes a vertically tapered geometry and yields a record 86% coupling efficiency using a lensed, uncoated, single-mode fiber. Cleaved fiber to InP-based waveguide coupling loss sensitivity is measured to be better than 1 dB with 1.85-m lateral fiber misalignment and 1.5-m transversal fiber misalignment.

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InP/ InGaAsP tensile strained multiple quantum wells are grown by MOCVD technique. The strain magnitude of quantum well is adjusted according to the intensities of TE and TM outputs from the fabricated broad lasers. The structure of polarization insensitive semiconductor amplifier is obtained.

The demanding technical requirements for solid oxide fuel cell (SOFC) interconnect materials pose development challenges for commerciallyviable systems. SOFC interconnects physically separate and manifold fuel (reducing) and oxidant (oxidizing) gases, while electrically connecting adjacent cell electrodes (anode to cathode) into series, and also permitting SOFC stacking and sealing. Due to the challenging multifunctional requirements, SOFC interconnect material investigations are intensifying to enable deployment of highly-efficient and inexpensive SOFC systems. Commercial ferritic stainless steels are used as interconnects in SOFC operating at ∼ 800°C. They contain elements such as Rare Earths, Mn, Al, and Ti as microalloying elements, designed to produce a thin surface oxide layer with specific characteristics: high mechanical strength; excellent adhesion to the metallic substrate; low growth rate (interconnect durability must be around 40,000 h); high chemical resistance (to avoid Cr depletion and electrode poisoning) and, low area specific resistance (ASR b 10 − 1 Ω·cm 2 ). However, long-term performance of commercial and even speciality ferritic stainless steels remains insufficient, and therefore surface treatments and/or coatings are required. These treatments have several important tasks, with the most important being to stabilize condensed-phase Cr(III) compounds in order to limit formation of volatile Cr (VI) compounds, which are responsible of SOFC cathode poisoning. This paper deals with the efficacy of two different kind of promising coatings: reactive element oxide nanolayers, produced by metal-organic chemical vapour deposition (MOCVD); and, dual segment coatings (CrAlYO + CoMnO), obtained by filtered arc deposition for the CrAlYO bottom segment and filtered arc-assisted electron beam physical vapour deposition for the CoMnO top segment. The coatings were applied on Crofer 22 APU (a commercial ferritic stainless steel from Thyssenn Krupp VDM) and tested under conditions simulating the aggressive service environment of a SOFC interconnect.

Cyclic azasilanes have been synthesized for the purpose of developing coupling agents appropriate for a variety of nanotechnologies including surface modification of nanoparticles, nanocrystals, mesoporous materials and substrates. N-Methyl-aza-2,2,4-trimethylsilacyclopen-tane is representative of this class of compounds. Preliminary data for the treatment of inorganic surfaces, including nanoparticles and oxidized silicon wafers, with cyclic azasilanes suggest high-density monolayer deposition by a ring-opening reaction. Cyclic azasilanes contain a cryptic amine functionality that can perform a subsequent tandem coupling reaction with functional molecules after the surface-triggered ring-opening reaction, allowing for a one-pot self-assembly route on nanostructures. Tandem coupling reactions are demonstrated via addition reactions of the cryptic amine with epoxy and acrylate systems .

0 . 1~ T-gate devices were fabricated. They were isolated by Mesa formation using wet chemical etching (H3PO&02M20 = 5/1/40). Ge/Au/Ni/Au was electron-beam evaporated for the ohmic contacts and followed by rapid thermal annealing at 340°C for 30s. The typical ohmic contact resistivity was in the order of 0.2Qmm. The 0 . 1~ T-gates were defmed by electron beam lithography using a bi-level resist profile. A selective succinic acid and hydrogen peroxide with an Iq,3Al,,7As/In,,3G~,7As etch selectivity > 500 [9] was used for the single recess etching, and the Ti/Pt/Au gate metallisation was electron-beam evaporated. The devices were not passivated. Fig. 3 Power gain (maximum available gain and maximum stable gain) and current gain Hz, against frequency for 0 . l p MM-HEMT at Vds = 1.5 V and Vgs = 0 V 0 power gain MAG MSG A current gain H21

One of the key requirements to achieve solar conversion efficiencies greater than 50% is a photovoltaic device with a band gap of 2.4 eV or greater. InxGa1-xN is one of a few alloys that can meet this key requirement. InGaN with indium compositions varying from 0 to 40% is grown by both metal-organic, chemical-vapor deposition (MOCVD) and molecular beam epitaxy (MBE), and studied for suitability in photovoltaic applications.

E-beam pumped lasers are attractive for Laser Cathode Ray Tubes (LCRT) in projection displays and a variety of applications typically associated with optically pumped lasers. For the first time an InGaN/GaN multiple quantum well (MQW) in-plane laser pumped by surface normal pulse and scanning electron beams was demonstrated. Pumping at room temperature (RT) and 80 K showed peak stimulated emission wavelengths of 402 and 409 nm with a full width half maximum (FWHM) of 0.6 nm and 1.2 nm, respectively. The threshold electron beam current densities have been estimated as 60 A/cm 2 for 35 keV electron energy at 80 K using scanning e-beam pumping and 200-300 A/cm 2 at RT using pulsed e-beam pumping with a maximum electron energy of 150 keV. At 80 K, light output of 150 mW was measured out of one facet at an e-beam current of 1.7 mA.

GaAs/AIGaAs vertical-cavity top-surface-emitting lasers with a continuously graded mirror composition have been grown by MOCVD, and planar devices with proton-implant current confinement have been characterized. Continuous grading of the heterointerfaces in the Bragg reflectors eliminated the energy-band discontinuities, thus improving carrier transport and resulting in a substantial reduction in the series resistance and threshold voltage of the laser diodes. These VCSEL's have excellent room-temperature CW electrical characteristics, including some of the lowest series resistance, highest power efficiency, and lowest operating voltages ever reported.

For the first time, HfZrO 4 dielectrics deposited with metal-organic chemical vapor deposition (MOCVD) as well as atomic layer deposition (ALD) have been investigated as high-k gate dielectric for 32-nm high-performance logic SOI complementary metal-oxide-semiconductor devices in this letter. The composition of the HfZrO 4 films has been analyzed in detail by atom probe tomography, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. Optical inline measurements and electrical parameters such as gate leakage current, capacitance equivalent thickness, threshold voltage, and performance as well as reliability data have been taken into account to directly compare both deposition methods. All parameters indicate a comparable behavior for MOCVD and ALD. Therefore, MOCVD has been demonstrated to be a promising alternative to ALD in high-volume manufacturing.

NiO films were grown by metal-organic chemical vapor
deposition (MOCVD) using bis-(ethylcyclopentadienyl)
nickel [(EtCp)2Ni] and oxygen or ozone as precursors.
The kinetic regularities of MOCVD processes were experimentally studied in the deposition temperature range
600-820 K for the reaction systems: (EtCp)2Ni–O2–Ar
and (EtCp)2Ni–O3–O2–Ar. The results obtained show that
the deposition processes in the temperature range 600-
700 K are controlled by kinetics and the value of activation
energy of the processes is 80±5 kJ·mol−1 in both cases.
The growth process in the temperature region 700–
840 K is controlled by mass transport. An introduction of
ozone in the reaction gas phase led to nearly twofold decrease of deposition rate probably because of homogeneous reactions with (EtCp)2Ni.

Aluminium tri-iso-propoxide (ATI) is a common precursor for the MOCVD of alumina coatings. However, little is known on its long term stability while its saturated vapour pressure in function of the temperature is controversial. The present contribution deals with these questions through FTIR, TGA and vapour pressure measurements. Low pressure MOCVD from ATI was performed in the temperature range 250-700°C. Whereas the pyrolytic decomposition of ATI leads to hydroxo species free alumina films above 415°C, it is shown in this paper that the thermal decomposition of ATI in the presence of water vapour yields pure alumina films at temperatures as low as 300-350°C. The films prepared in the range 250-700°C do not diffract X-rays. Arrhenius plots for both pyrolytic (E a ∼ 12 kJ/mole) and water assisted (E a ∼ 9 kJ/mole) decomposition reveal diffusion-limited processes with higher growth rate values in the former case.

Increasing demand for high brightness LEDs for LCD TV backlighting and solid-state lighting requires MOCVD growth of GaN at high growth rates (4 5 mm/h) with high crystalline quality in mass production reactors. Understanding the MOCVD growth parameters on the quality of GaN materials and growth efficiency are important for quickly setting up process windows for the optimization and qualification of new LED growth processes. We have investigated the effects of N 2 /H 2 ratio, N 2 /NH 3 ratio, and growth temperature on the growth efficiency, crystal quality, morphology, yellow-band emission (YE), and sheet resistance of un-doped GaN epitaxial layers using design of experiment (DOE) methodology. Our results indicate that high growth temperature (at 1080 1C) and low N 2 /H 2 ratio (set at 0.5 in the DOE) were the common factors for achieving better crystal quality, smoother surface, and lower YE intensity in GaN epitaxial layers, as well as for obtaining higher growth efficiency in MOCVD of GaN.

InGaN/GaN based blue LEDs with 2-mm-thick crack-free GaN buffer layers were successfully grown and fabricated on patterned Si (1 1 1) substrates. The patterns on the substrates include 340 mm  340 mm square islands, separated by 3-mm deep and 20 mm wide trenches, along the h1l 0i and h1 12i crystalline orientations. In addition to using the patterned growth technique, thin AlN and SiN x interlayers grown at high temperatures were also employed to partially release the residual stress and to further improve the crystalline quality. Blue LEDs of 300  300 mm 2 fabricated on the islands, without thinning and packaging, exhibited a high output power of around 0.7 mW at a drive current of 20 mA. Compared to III-nitride LEDs grown on sapphire substrates, the same LED structures grown on patterned Si substrates showed a few nm of red shift in emitting wavelength, suggesting some residual stress of GaN on patterned Si. r

In this work we studied PL in ZnO layers and nanostructures, including ZnO homoepitaxial layers on ZnO substrate and ZnO-Zn 1Àx Mg x O single quantum well (SQW) structures grown on sapphire substrates by MBE, and ZnO nanowires grown on sapphire by MOCVD. The external quantum efficiency (QE) of PL in O-face ZnO layers exceeded that in Zn-face ZnO layers by two orders of magnitude at low temperatures. In a sample with SQW the combined external QE from the 4.6-nm-wide SQW and 50-nmthick Zn 1Àx Mg x O barriers achieved 28% at 15 K. The highest external QE was observed in one of the samples with ZnO nanowires-52% at 15 K and 2% at 300 K. Contribution of defect-related PL bands in ZnO nanowires samples was extremely low.

Surface morphology studies of GaN and AlGaN grown by metalorganic chemical vapor deposition (MOCVD) have been carried out using atomic force microscopy. The open core dislocation and steps connecting two threading dislocations of opposite direction are commonly observed in undoped and doped GaN. Structural studies on AlGaN epitaxial layers grown on undoped GaN revealed the formation of open-core dislocation with width upto 300 nm. The nanopipes originate from the threading dislocation formed due to large lattice mismatch between sapphire and GaN. The mismatch also leads to high strain in the epilayers resulting in cracking effect at the edges of the hexagonal V-type defect. The self organized quantum dots features on the smooth surface of AlGaN epitaxial layer exhibit the Stranski-Krastanov(SK) mode of island growth.

InGaN/GaN single and multi quantum wells have been grown by metal-organic chemical vapor deposition, varying the growth rate of well and barrier layers as well as the Si-doping of the GaN barriers. Separately, the effect of these growth parameters on the surface morphology of thin GaN and InGaN layers grown under the same conditions had been studied. The surface morphology of the layers strongly influenced the structural properties of the multi quantum wells. The optical properties seemed to be less affected by the observed layer thickness fluctuations in the 200-500 nm range rather than by variations in the indium composition on a shorter length scale.

N-p-n Al0.05GaN/GaN heterojunction bipolar transistors with a common emitter operation voltage higher than 330 V have been demonstrated using selectively regrown emitters. Devices were grown by metalorganic chemical vapor deposition on sapphire substrates. The n-type emitter was

A ''single-source'' Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5 (dmae)] 2 (dmae=OCH 2 CH 2 NMe 2 ), has been used for atomic vapour deposition (AVD) of SrBi 2 Ta 2 O 9 (SBT). This single-source precursor is designed to alleviate the mismatch between conventional Sr and Ta sources. Strontium tantalate thin films were deposited on silicon using the Sr[Ta(OEt) 5 (dmae)] 2 , and the optimum temperatures for deposition of strontium tantalate with a Sr:Ta ratio of 0.5 was found to be $510 1C. Deposition of Bi-oxide films using Bi(mmp) 3 (mmp=OCMe 2 CH 2 OMe) indicates similar decomposition behaviour to the Sr-Ta alkoxide precursor, demonstrating its suitability as a complementary source of Bi for SBT. The co-incorporation of Bi and Sr within the SBT films is promoted through the deposition of bismuth oxide/strontium tantalate super lattices. After post-growth annealing the super lattices are converted to strontium bismuth tantalate thin films. r

Dilute nitride Ga(In)NAs/GaAsSb "W" type II quantum wells on GaAs substrates have been grown by metal-organic chemical vapor deposition (MOCVD). Design studies underscore the importance of nitrogen incorporation to extend the emission wavelength into the 1.5 µm region as well as increase the electron confinement, given the material strain relaxation limitations. These studies also indicate that the Sb content of the GaAs 1 −x Sb x hole well is required to be greater than x ∼ 0.2, to provide adequate hole confinement (i.e., ∆E v > 150 meV). Photoluminescence (PL) and electroluminescence (EL) studies are used to characterize the optical transitions and compare with a ten-band k.p simulation. We find that the lowest energy type II transition observed is in good agreement with theory. Preliminary results are presented on diode lasers with two-and three-stage "W"-active regions that exhibit emission that is blue-shifted from the PL, due to charge separation and carrier band-filling of higher energy transitions. Further structure optimization, including multiple-stage (eight to ten Wstages) active regions is required to lower the threshold carrier density and minimize carrier band-filling and built-in electric field effects resulting from charge separation. Dilute nitride materials, such as GaAs 1 −y−z Sb y N z /InP, are also under development offering potential for wavelength extension into the mid-IR employing InP substrates.

Preliminary results on the study of deep levels associated with 4d-transition metal, rhodium, in crystalline GaAs grown by metal-organic chemical vapour deposition (MOCVD) technique are reported for the first time. Deep level transient spectroscopy on n-type GaAs doped in situ with Rh during MOCVD growth reveals a broad majority carrier emission peak. The peak corresponds to a band of deep levels extending over the energy range 0.57-0.65 eV below the conduction band edge with lower-energy states having lower electron capture cross-sections. The deep levels show a pronounced dependence of electron emission rate on the junction electric field. Minority carrier (hole) emission spectra at zero bias show a pronounced Rh-related deep-level peak with a low-temperature shoulder. The dominant level in the lower half-gap is found to have a position E v þ 0:44 eV, with a field-dependent emission rate signature. r

A~tract-Various routes to praseodymium alkoxides have been investigated. Compounds such as PrsO(OR)J3 [R = Pr i (1), Aml], [Pr402(ONp)s]m (Np = neopentyl), [Pr(OC2H4NMe2)3]3 were obtained by reaction of praseodymium turnings with the corresponding alcohols. Alcoholysis reactions of the bis-trimethylsilylamide afforded [Pr40(ONp)lo]m, [Pr402(ONp)s],,, Pr3(OR)9(ROH)2 [R = Bu', Am'] and [Pr402(OC2H4OMe)s]m (2a), the latter derivatives illustrating the trend for the formation of oxo species. The compounds were characterized by elemental analysis, FT-IR and NMR. Their reactivity has been investigated, the mixed-metal species Pr4TiO(OPP)I4 and Y4PrO(OPri)~3 were obtained.

We report the growth and characterization of mid-wavelength infrared type-II InAs/InAs1xSbx superlattice photodiodes on
GaSb substrates grown by metal-organic chemical vapor deposition. At 150 K, the 50% cut-off wavelength is 5.0 lm, the dark current density is 3.3x 10^4 A/cm^2 under 20 mV bias, and the peak responsivity is 1.76 A/W corresponding to a quantum efficiency
of 55% without anti-reflection coating. A specific detectivity of 1.2 x 10^11 cm Hz^1/2/W is achieved at 4.0 um under 20 mV bias at
150 K

AlGaN/AlN/GaN/lnGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) structures with improved buffer isolation have been investigated. The structures were grown by MOCVD on sapphire substrate. AFM result of this structure shows a good surface morphology with the root-mean-square roughness (RMS) of 0.196 nm for a scan area of5J.lm x 5J.lm. A mobility as high as 1950 cm 2 N s with the sheet carrier density of 9.89xl0 12 cm-2 was obtained, which was about 50% higher than other results of similar structures which have been reported. Average sheet resistance of 327 .Q/sq was achieved. The HEMTs device using the materials was fabricated, and a maximum drain current density of 718.5 mA/mm, an extrinsic transconductance of 248 mS/mm, a current gain cutoff frequency of 16 GHz and a maximum frequency of oscillation 35 GHz were achieved.

We have performed a detailed investigation of the metal-organic chemical vapor deposition (MOCVD) growth and characterization of InN nanowires formed on Si(1 1 1) substrates under nitrogen rich conditions. The growth of InN nanowires has been demonstrated by using an ion beam sputtered ( $ 10 nm) Au seeding layer prior to the initiation of growth. We tried to vary the growth temperature and pressure in order to obtain an optimum growth condition for InN nanowires. The InN nanowires were grown on the Au +In solid solution droplets caused by annealing in a nitrogen ambient at 700 1C. By applying this technique, we have achieved the formation of InN nanowires that are relatively free of dislocations and stacking faults. Scanning electron microscopy (SEM) showed wires with diameters of 90-200 nm and lengths varying between 3 and 5 mm. Hexagonal and cubic structure is verified by high resolution X-ray diffraction (HR-XRD) spectrum. Raman measurements show that these wurtzite InN nanowires have sharp peaks E 2 (high) at 491 cm À 1 and A 1 (LO) at 591 cm À 1 .

We have investigated the performance and potential benefit of acoustic sensing for real-time monitoring and closed loop control of binary gas mixture compositions delivered from low vapor pressure metalorganic sources. Two solid phase sources were investigated in the presence of H 2 as a carrier gas: (1) trimethylindium (TMI) and (2) bis(cyclopentadienyl) magnesium ͑Cp 2 Mg͒, which have room temperature ͑25°C͒ vapor pressures of 2.5 and 0.04 Torr, respectively. An acoustic sensor was implemented on the gas feed line to measure the concentration-dependent speed of sound in the gas mixture. This enabled sensitivity and control at precursor levels as low as 0.6 ppm in H 2. Closed loop process control was implemented to maintain TMI and Cp 2 Mg concentration target in the presence of intentionally introduced long term temperature drifts. Despite induced variations of the precursor vapor pressure up to 50%, the delivered composition was controlled to within ±0.15% for TMI (at 0.5 mol% set point) and ±0.3% for Cp 2 Mg (at 0.01 mol% set point). Short term variability could also be substantially reduced by the control scheme. This work demonstrates the feasibility of sensor-driven control systems for stable delivery of low vapor pressure, normally problematic precursor materials. In turn, this opens the door to utilization of a broader range of species which can be synthesized as chemical precursors.

Lapisan tipis In 2 O 3 telah ditumbuhkan di atas substrat gelas dengan metode MOCVD menggunakan prekursor metal organic In(TMHD) 3. Parameter penumbuhan yang digunakan adalah: temperatur bubbler untuk menguapkan In(TMHD) 3 200 o C, tekanan bubbler 260 Torr, temperatur substrat 300 o C, laju alir gas Ar 50 sccm, laju alir gas O 2 50 sccm, tekanan total penumbuhan 2x10-3 Torr, dan waktu penumbuhan 120-180 menit. Tiga jenis lapisan tipis In 2 O 3 dihasilkan yang dibedakan oleh ketebalannya, yaitu 531, 434, dan 404 nm. Sifat optik lapisan diinvestigasi dengan menggunakan alat Spectrophotometry UV-Vis. Diperoleh bahwa transmitansi ketiga lapisan pada rentang panjang gelombang sinar tampak rata-rata di atas 80%. Perbedaan ketebalan lapisan sekitar 127 nm tidak mempengaruhi secara signifikan karakteristik transmisi optiknya. Lebar celah pita energi ketiga lapisan In 2 O 3 terentang dari 3,76-3,80 eV. Sementara lebar pita energi Urbach-nya terentang dari 0,20-0,22 eV. Ketiga lapisan tipis In 2 O 3 yang tumbuh memiliki karakteristik transisi tidak langsung ke pita terlarang. Kata kunci : Sifat optik; Lapisan tipis; In 2 O 3 ; Metal organic; In(TMHD) 3 ; MOCVD.

We evaluate temperature effects on threshold current and slope efficiency of 1.55µm Fabry-Perot lasers between 20 o C and 120 o C. Experimental results are analyzed using the commercial laser simulator PICS3D. The software self-consistently combines two-dimensional carrier transport, heat flux, strained quantum well gain computation, and optical wave guiding with a longitudinal mode solver. All relevant physical mechanisms are considered, including their dependence on temperature and local carrier density. Careful adjustment of material parameters leads to an excellent agreement between simulation and measurements at all temperatures. At lower temperatures, Auger recombination controls the threshold current. At high temperatures, vertical electron leakage from the separate confinement layer mainly limits the laser performance. The increase of internal absorption is less important. However, all these carrier and photon loss enhancements with higher temperature are mainly triggered by the reduction of the optical gain.

Blue light-emitting diodes (LEDs) with an InGaN multi-quantum well (MQW) structure were fabricated on a patterned sapphire substrate (PSS) using a single growth process of metal organic chemical vapor deposition (MOCVD). The electrical and optical properties of these LEDs were investigated. The crystal quality of epitaxial GaN film was improved by using the PSS structure. At 40 mA injection current, the peak wavelength and the full-width at half-maximum of the electroluminescence spectra of PSS were 461 and 24 nm, respectively. The electroluminescence intensity (EL) of LEDs grown on patterned substrate was 2.44 times greater than that of unpatterened sapphire substrate (UPSS). The operating voltage was measured about 3.1 V for the LED with a PSS structure. This significant increase resulted from the improvement of the epitaxial quality of the InGaN/GaN epilayers and the improvement of the light extraction efficiency through patterned sapphire substrates.

This paper presents the X-band and C-band power performance of MOCVD grown N-polar AlGaN/GaN MIS-HEMTs grown on semi-insulating SiC substrates. Additionally, an Ah03 based etch stop technology was demonstrated for improving the manufacturability of N-polar GaN HEMTs with SixNy passivation. The reported output power densities of 16.7 W/mm at 10 GHz and 20.7 W/mm at 4 GHz represent the highest reported values so far for an N-polar device, at both of these frequencies. N-polar AlGaN/GaN HEMTs have demonstrated excellent small signal performance [1 ] and large signal performance comparable to Ga-polar devices in terms of power added efficiency (PAE) [ 2,3]. However, maximum output power obtained from the N-polar devices was limited by the low breakdown voltage of MBE grown devices [ 2], and high self-heating for devices grown on sapphire substrate by MOCVD [3 ]. N-polar HEMTs grown by MOCVD on n-type SiC by Brown et al.

Copper metal films were grown on single-crystal strontium titanate (100) by the thermal decomposition of copper dimethylamino ethoxide in inert atmosphere at temperatures between 150 and 270 "C. Films grown at 200 "C are copper metal, free from contaminants, while higher temperatures result in significant carbon and oxygen incorporation. Deposition products were identified by Fourier transform infrared spectroscopic analysis of the reactor gas phase in situ and by mass spectroscopic analysis of the reactor exit gas during deposition. At 200 "C, deposition occurs by interdependent ,&hydride elimination and reductive elimination reactions which produce (dimethylamino)ethanal, (dimethylamino)ethanol, and copper metal. @-Hydride and reductive elimination reactions are also dominant at 250 "C; however, the competition of ligand fragmentation reactions with the whole-ligand eliminating reactions leads to carbon and oxygen contamination of the copper metal film. (3) Shin, H. K.; Chi, K. M.; Hempden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. Adv. Mater. 1991,3, 246248. (4) Beach, D. B.; LeGoues, F. K.; Hu, C. K. Chem. Mater. 1990, 2, 216219. (5) Hampden-Smith, M. J.; Kodas, T. T.; Paffett, M.; Farr, J. D.; Shin, H. K. Chem. Mater. 1990,2,636-639. (6) (a) Chi, K. M.; Shin, H. K.; Hampden-Smith, M. J.; Kodas, T. T.; Duesler, E. N. Inorg. Chem. 1991,30,4293-4294. (b) Jain, A.; Chi, K. M.;Kodas,T.T.;Hampden-Smith,M. J.;Farr,J.D.;Paffett,M.F. Chem. Mater. 1991,3,995-997. (c) Baum, T. H.; Larson, C. E. Chem. Mater. 1992, 4, 365. (7) Fine, S. M.; Dyer, P. N.; Norman, J. A. T.; Muratore, B. A,;

The inherent advantages of the hot-wall metal organic chemical vapor deposition (MOCVD reactor (low temperature gradients, less bowing of the wafer during growth, efficient precursor cracking) compared to a cold-wall reactor make it easier to obtain uniform growth.

One of challenges in improving the performance and cost-effectiveness of solid oxide fuel cells (SOFCs) is the development of suitable interconnect materials. Recent researches have enabled to decrease the operating temperature of the SOFC from 1000 to 800 • C. Chromia forming alloys are then among the best candidates for interconnects. However, low electronic conductivity and volatility of chromium oxide scale need to be solved to improve interconnect performances. In the field of high temperature oxidation of metals, it is well known that the addition of reactive element into alloys or as thin film coatings, improves their oxidation resistance at high temperature. The elements of beginning of the lanthanide group and yttrium are the most efficient. The goal of this study is to make reactive element oxides (La 2 O 3 , Nd 2 O 3 and Y 2 O 3 ) coatings by metal organic chemical vapour deposition (MOCVD) on Crofer 22 APU, AL 453 and Haynes 230 in order to form perovskite oxides which present a good conductivity at high temperature. The coatings were analysed after 100 h ageing at 800 • C in air under atmospheric pressure by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Area-specific resistance (ASR) was measured in air for the same times and temperature, using a sandwich technique with Pt paste for electrical contacts between surfaces. The ASR values for the best coating were estimated to be limited to 0.035 cm 2 , even after 40,000 h use. (S. Fontana). temperature favors rapid reaction kinetics and allows reforming of hydrocarbon fuels within the fuel cell (internal reforming). In addition, SOFCs generate very low levels of pollutants with a high power density. A SOFC is composed of two porous electrodes, an anode and a cathode, separated by a gas imperviousness ion-conducting electrolyte. The interconnect provides electrical connection between anode of one individual cell to the cathode of the neighbouring one. It also acts as physical barrier to avoid any contact between the reducing and the oxidising atmospheres. In order to perform their intended functions, interconnects should have the following characteristics [1-3]:

In this study, we investigated the effect of Al pre-deposition time on GaN crystal quality. The GaN layer was grown on a Si (111) substrate by metal organic chemical vapor deposition using an AlN buffer layer. Atomic force microscopy, scanning electron microscopy and X-ray diffraction were used to evaluate film growth. Consequently, we found significant differences in the epitaxial properties of the AlN buffer and GaN layer, which were dependent on the Al pre-deposition time. When the deposition time was 0s, the AlN buffer layer was very smooth, but the GaN layer did not have a high crystal quality. At a Al pre-deposition time of 60s, the AlN buffer started to be transformed into a rough surface and the GaN layer had both a mirror-like surface and better crystal quality. When the Al predeposition time was greater than 120s, GaN surfaces had a high roughness. In addition, the surface morphology of the GaN had not coalesced. Based on these results, the optimized Al pre-deposition time was found to be essential to achieve an appropriate surface roughness for high crystal quality of GaN.