Open circuit voltage in homojunction and heterojunction silicon solar cells grown by VHF-PECVD

We present homojunction and micro-c-Si/a-Si:H/c-Si heterojunction silicon solar cells fabricated by PECVD. The H2 dilution used during the i-layer growth strongly affects the device efficiency. While intermediate H2 dilution of the gas mixture results in V-infinite degradation, the best V-infinite is obtained under zero or very high (= 99.4%) H2 dilution, resulting in totally amorphous or epitaxial i-layer respectively. A maximum value of 638 mV, with 13.7% e.ciency, is observed in the case of an amorphous i-layer, indicating an improvement of interface quality. If the i-layer is deposited using a 99.4% H2 dilution, a 608 mV V-infinite is observed and for homojunction solar cells a 13.1% efficiency is obtained.