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Uniformity and repeatability of InAlN-barrier HEMTs growth by high-speed-rotation single-wafer MOCVD tool
摘要： We fabricated high-electron-mobility transistor structures with InAlN as a barrier layer on 8- or 6-inch Si substrates by using a recently developed high-speed-wafer-rotation single-wafer MOCVD tool. It has been reported that Ga inclusion in the InAlN layer causes serious problems in the control of group III metal composition in some cases, but the samples grown using the tool exhibited an InAlN layer with an abrupt interface and almost no Ga inclusion. Excellent in-wafer uniformity, repeatability, and wafer-to-wafer uniformity of device structure are also reported. The results shown in this paper indicate high performance of the tool in the real production of devices.
关键词： A3. Metalorganic vapor phase epitaxy,B1. Nitrides,B2. Semiconducting III-V materials,B3. High electron mobility transistors
更新于2025-09-23 15:23:52
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Morphological study of InGaN on GaN substrate by supersaturation
摘要： The morphology of thin InGaN layers grown on c-plane GaN substrates by metalorganic vapor phase epitaxy (MOVPE) has been studied by atomic force microscopy. Three different morphologies appeared, a stepped surface, large flat two-dimensional (2D) islands and small high three-dimensional (3D) dots. Low growth temperature and high growth rate (i.e. increased vapor supersaturation) changed the InGaN morphology from steps to 2D islands and then 3D dots (when exceeding the critical thickness for 3D dots). Larger miscut angle of GaN substrate changed the morphology from 2D islands to step by decreasing the surface supersaturation of individual terraces. InGaN layers with a stepped morphology had the highest internal quantum efficiency at similar InN mole fraction. InGaN grown on GaN substrate more easily achieved a stepped morphology compared to InGaN on GaN/sapphire templates.
关键词： A3. Metalorganic vapor phase epitaxy,B2. Semiconducting III-V materials,A1. Crystal morphology,B1. Nitride
更新于2025-09-23 15:22:29
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InAs/GaSb thin layers directly grown on nominal (001)-Si substrate by MOVPE for the fabrication of InAs FINFET
摘要： We demonstrated the fabrication of a densely packed InAs fins network for nanoelectronic applications. High crystalline quality GaSb/InAs layers have been grown directly on 300 mm nominal (001)-Si substrate. The InAs was then processed by etching step using a lithographic mask based on block copolymer to obtain sub-20nm width fins. This block copolymer has been optimized to self-assemble into lamellar structure with a period of 30nm, standing perpendicular to the substrate thanks to a neutral layer. STEM-HAADF characterization displays vertical sidewalls InAs fins with a width as low as 15nm spaced by almost 10nm. Early electrical characterizations exhibit a current flow through the connected fins.
关键词： B3 High electron mobility transistors,B3 Field effect transistors,A3 Organometallic vapor phase epitaxy,A1 Etching,B2 Semiconducting III-V materials
更新于2025-09-23 15:22:29
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Zinc blende and wurtzite crystal structure formation in gold catalyzed InGaAs nanowires
摘要： III-V semiconductor nanowires made of materials which have the zinc blende crystal structure in bulk are well known to exhibit either the zinc blende or the wurtzite crystal structure. Understanding and controlling which crystal structure that forms is of highest importance for nanowire applications in a variety of areas. In addition to this, composition control in ternary nanowires is another key technology area for successful nanowire applications. We derive a general model, based on two-component nucleation theory, which we use to explain the so far less understood experimental observations of zinc blende, wurtzite, and mixed crystal structure as a function of growth conditions and composition, x, in gold catalyzed InxGa1-xAs nanowires. An interesting theoretical finding is that the wurtzite and zinc blende phases have different compositions, even if they are nucleated from the same catalyst particle at the same conditions.
关键词： A1. Nanostructures,A1. Nucleation,A1. Crystal structure,B2. Semiconducting III-V materials,B2. Semiconducting ternary compounds
更新于2025-09-23 15:22:29
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Fabrication of AlN templates on SiC substrates by sputtering-deposition and high-temperature annealing
摘要： High-quality AlN templates fabricated by sputtering-deposition and post-deposition high-temperature annealing have great potential for deep ultraviolet light-emitting device applications. In this work, we fabricated AlN films on 6H-SiC substrates by sputtering and face-to-face annealing and characterized the structural quality of the AlN films before and after annealing. As reported in previous studies, to accomplish high-quality AlN films on SiC substrates using conventional methods, such as molecular beam epitaxy or metalorganic vapor phase epitaxy (MOVPE), it is important to grow the AlN on the SiC coherently. However, in this work, although the annealed AlN films were fully relaxed from the SiC substrates, or even had tensile strain, the AlN films indicated high crystallinity. The X-ray rocking curve full width at half maximum (XRC-FWHM) values of the 200-nm-thick annealed AlN film were 17 and 246 arcsec for the AlN (0002) and (10–12) diffraction, respectively. Though the annealed AlN film indicated rough surfaces with bunched step structures, the surface morphology was remarkably improved by MOVPE growth and clear atomic step-and-terrace structures were formed. The XRC-FWHM values of the MOVPE-grown AlN were 90 and 239 arcsec for the AlN (0002) and (10–12) diffraction, respectively.
关键词： A1. Stresses,A1. Atomic force microscopy,B1. Nitrides,B2. Semiconducting III-V materials,A1. X-ray diffraction
更新于2025-09-23 15:22:29
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Effect of Buffer Layer Structure on the Structural Properties of GaAs Epitaxial Layers Grown on GaP Substrates
摘要： Three-μm-thick GaAs layers were grown on 2°-off (100) GaP substrates by employing various buffer layer structures, which consist of GaAsP- and InGaAs-based ternary compound semiconductors. To confirm the effects, we altered the layer thickness, the interface lattice mismatch, and number of the layers in the buffer layer structure, and also a superlattice structure was employed in some of the buffer layers. The lattice constants of the layers were controlled by changing the As/P and In/Ga compound ratios. The crystal properties of the grown GaAs layers were characterized with X-ray diffraction, photoluminescence, and etch pit density observations. The effect of the buffer layer structure on the crystallographic character of the GaAs layers was analyzed by introducing a parameter that is a function of the thickness and interface lattice mismatch of each layer in the buffer layer structure. The results suggest that the GaAs layer is relatively relaxed but contains a greater number of dislocations for smaller layer thicknesses and greater lattice mismatches in the buffer layer structure, while the GaAs layer has a smaller number of dislocations but a rather deformed lattice structure for larger layer thicknesses and smaller lattice mismatches. Our parameter is useful for developing design principles of buffer layer structures.
关键词： A3. Heteroepitaxial growth,B2. Semiconducting III-V materials,B3. Solar cells,A3. Metalorganic vapor phase epitaxy
更新于2025-09-23 15:21:01
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GaAs solar cells grown on intentionally contaminated GaAs substrates
摘要： III-V materials such as GaAs and GaInP have some of the best electronic and optical properties of any semiconductor materials, but deposition of these materials relies on high-quality single crystal GaAs substrates for their superior performance. Unfortunately, the cost of these substrates makes these high-efficiency devices only accessible in high-value or niche markets. Here, we explore the effect of growing bulk GaAs crystals with lower purity input materials in order to reduce their cost. We observe that intentional impurities added to the melt before the crystal growth occurs segregate to the top of the boule. Single junction GaAs solar cells grown on substrates made from contaminated boules showed no performance degradation compared to a high-purity control substrate. These results suggest that lower purity Ga and As source materials can be used during crystal growth to reduce the cost of substrates.
关键词： B2. Semiconducting III-V materials,A2. Gradient freeze technique,A1.Substrates,B3. Solar Cells
更新于2025-09-23 15:19:57
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GaN grown by metalorganic vapor phase epitaxy
摘要： We report on residual impurities in semi-polar (3031) and (2021) GaN homo-epitaxial layer grown by metal-organic chemical vapor deposition. The (3031) and (2021) GaN layer showed atomically smooth surface and clear steps toward [0001] and [000-1], respectively. The residual impurity concentrations of oxygen and carbon were below the detection limit of secondary-ion mass spectroscopy. Low-temperature photoluminescence revealed that (2021) GaN layer consisted free excitons and Si donor bound excitons, along with two-electron satellite lines and longitudinal optical (LO) phonon coupling transitions. The results indicate semi-polar (3031) and (2021) GaN epitaxial layers are promising candidates in obtaining a high quality GaN drift layer for vertical GaN devices.
关键词： B2. Semiconducting III-V materials,A3. Metalorganic chemical vapor deposition,B1. Nitrides,A1. Crystal structure,A1. Impurities
更新于2025-09-19 17:15:36
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Highly tin doped GaAs at low growth temperatures using tetraethyl tin by metal organic vapor phase epitaxy
摘要： GaAs layers with a high tin (Sn) doping concentration and a smooth surface morphology were successfully grown at temperatures as low as 425 °C using tetraethyl tin (TESn) by metal organic vapor phase epitaxy (MOVPE). The samples grown at 650 °C showed Sn-rich droplets even with a low TESn molar flow rate of 0.06 μmol/min, indicating that Sn atoms were not incorporated into the GaAs film but segregated and accumulated on the film surface. Droplet formation was suppressed at a low growth temperature of 425 °C. This suggests that the segregation process is kinetically-limited, with the segregation mechanism is slow compared to the growth rate at low growth temperatures. Uncorrected Hall effect measurements found an electron concentration of ～1 × 1019 cm?3, which is close to the maximum reported doping-limit obtainable in GaAs:Sn grown by MOVPE, while avoiding droplet formation and maintaining a smooth surface morphology. The electron mobility is dominated by the ionized impurity scattering. The sample possesses a generally flat Sn profile extending from the substrate to the film surface. Secondary ion mass spectroscopy indicates that the Sn is electrically active but compensated by carbon acceptors to yield the measured carrier concentration.
关键词： A1. Segregation,B2. Semiconducting III-V materials,A1. Doping,A3. Metalorganic vapor phase epitaxy
更新于2025-09-19 17:15:36
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Influence of the growth conditions of LT-AlN on quality of HT-AlN growth on Si (111) by metalorganic chemical vapor deposition
摘要： In this study, AlN films on Si(111) using LT-AlN nucleation layer with various conditions at TMAl preflow were grown and investigated. It was shown that the main factor influencing the quality of AlN films is the degree of the substrate coating by aluminium at preflow. The qualitative model of AlN growth using the LT-AlN nucleation layer for three different coverage by Al (high, optimal and low) was suggested. For the film grown under optimal conditions, the rocking curve FWHM for the AlN (0002) reflection was 0.59о. The demonstrated possibility of the high-quality growth of AlN films below 1000oС would be useful for high power electronics.
关键词： B1. Silicon,B1. Aluminum Nitride,B1. Nitrides,B2. Semiconducting III–V materials,A3. Metalorganic chemical vapor deposition,A1. Crystal structure
更新于2025-09-10 09:29:36