PREPARATION OF MU-C-SIC AND ITS APPLICATION FOR LIGHT-EMITTING-DIODES

We have investigated the preparation conditions of n-type muc-SiC films with high dark-conductivity (10(-3)-1 S/cm) and wide optical band gap (2.1-2.4 eV) deposited by electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) from two kinds of gas sources, SiH4 + CH4 + H-2 + PH3 and SiH4 + C2H2 + H-2 + PH3. It Was found that the deposition of the CH4-based muc-SiC films required a higher gas pressure (above 2.6 m Torr) than that used for conventional ECR CVD to suppress hydrogen ions impinging on an underlying layer. For the C2H2-based muc-SiC films, we found that besides the suppression of the hydrogen ions a large supply of the atomic hydrogen and the reduction of the C2H2/SiH4 were necessary. We have applied n-type muc-SiC to an electron injector of two kinds of Si-based light emitting diodes whose structures were Al/n-type muc-SiC/i-type a-SiC/a-SiN/p-type a-SiC/SnO2/glass, and indium tin oxide/n-type muc-SiC/porous Si/p-type c-Si/Au. In both diodes, we clearly observed visible light emission.