Preparation of μc-SiC and its application for light emitting diodes

We have investigated the preparation conditions of n-type μc-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, SiH 4 + CH 4 + H 2 + PH 3 and SiH 4 + C 2 H 2 + H 2 + PH 3 . It was found that the deposition of the CH 4 -based μc-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 C 2 H 2 -based μc-SiC films, we found that besides the suppression of the hydrogen ions a large supply of the atomic hydrogen and the reduction of the C 2 H 2 /SiH 4 were necessary. We have applied n-type μc-SiC to an electron injector of two kinds of Si-based light emitting diodes whose structures were Al/n-type μc-SiC/i-type a-SiC/a-SiN/p-type a-SiC/SnO 2 /glass, and indium tin oxide/n-type μc-SiC/porous Si/p-type c-Si/Au. In both diodes, we clearly observed visible light emission.