Papers by Keyword: Crystalline Quality

Abstract: High quality semipolar (1122) AlN films have been grown on (1010) m-plane sapphire substrates with the help of dual moderate-temperature-grown (MTG) AlN interlayers by using metal-organic chemical vapor deposition technology. The layer thickness of the semipolar (1122) AlN film was determined by employing relative optical transmittance spectrum measured with ultraviolet-visible spectrophotometer. The effect of the insertion of 80 nm-thick MTG AlN interlayer on structural and optical properties was investigated in detail based on the characterization results of the atomic force microscopy, high-resolution X-ray diffraction, and Raman spectroscopy. Comparing with the semipolar (1122) AlN film grown without the MTG AlN interlayer, both the surface morphology and crystalline quality of the semipolar (1122) AlN film grown with the insertion of dual 80 nm-thick MTG AlN interlayers have been improved significantly. In fact, the root mean square value of the surface roughness decreased from 3.5 to 1.4 nm, and the full width at half maximum value of X-ray rocking curve decreased from 1667 to 1174 arcsec, respectively. These facts reveal that the insertion of the dual MTG AlN interlayers is a powerful method to improve the surface morphology and crystalline quality of the semipolar (1122) AlN films owing to the formation of nanoscale patterned substrate-like structure and its blocking effect on the propagation of the dislocations.

Abstract: The GaAsP crystal material grown on GaAs substrate has been extensive applications in the area of photoelectronic device. There because GaAsP have advantageous photoelectronic performance and adjustable band gap. We report growth of GaAs1-xPx grown on GaAs substrate by solid source molecular beam epitaxy (SSMBE). On the basis of the optimized Ⅴ/Ⅲ flux ratio, appropriate growth rate, and the substrate temperature for sample growth, different composition GaAs1-xPx layers had been grown on GaAs top. Lattice-mismatched became the big challenges to high-quality epitaxial growth of the GaAs1-x Px materials on GaAs substrate. The crystalline quality, surface morphology were performed by applying high resolution X-ray diffractometry (HRXRD) and high resolution optical microscopy. The etched region and internal defect were also investigated.

Abstract: A novel approach to the high growth rate Chemical Vapor Deposition of SiC is described. The Halide Chemical Vapor Deposition (HCVD) method uses SiCl4, C3H8 (or CH4), and hydrogen as reactants. The use of halogenated Si source and of separate injection of Si and C precursors allows for preheating of source gases without causing premature chemical reactions. The stoichiometry of HCVD crystals can be controlled by changing the C/Si flow ratio and can be kept constant throughout growth, in contrast to the Physical Vapor Transport technique. HCVD was demonstrated to deposit high crystalline quality, very high purity 4H- and 6H-SiC crystals with growth rates comparable to other bulk SiC growth techniques. The densities of deep electron and hole traps are determined by growth temperature and C/Si ratio and can be as low as that found in standard silane-based CVD epitaxy. At high C/Si flow ratio, the resistivity of HCVD crystals exceeds 105
_cm. These characteristics make HCVD an attractive method to grow SiC for applications in high-frequency and/or high voltage devices.