Homoepitaxial Growth and Characterization of 4H-SiC Epilayers by Low-Pressure Hot-Wall Chemical Vapor Deposition

摘要

Horizontal air-cooled low-pressure hot-wall CVD (LP-HWCVD) system is developed to get high quality 4H-SiC epilayers. Homoepitaxial growth of 4H-SiC on off-oriented Si-face (0001) 4H-SiC substrates purchased from Cree is performed at a typical temperature of 1500℃ with a pressure of 40 Torr by using SiH_4+C_2H_4+H_2 gas system. The surface morphologies and structural and optical properties of 4H-SiC epilayers are characterized with Nomarski optical microscope, atomic force microscopy (AFM), x-ray diffraction, Raman scattering, and low temperature photoluminescence (LTPL). The background doping of 32 μm-thick sample has been reduced to 2-5x10~(15) cm~(-3). The FWHM of the rocking curve is 9-16 arcsec. Intentional N-doped and B-doped 4H-SiC epilayers are obtained by in-situ doping of NH_3 and B_2H_6, respectively. Schottky barrier diodes with reverse blocking voltage of over 1000 V are achieved preliminarily.