Effect of hydrogen dilution on intrinsic a-Si:H layer between emitter and Si wafer in silicon heterojunction solar cell

In silicon heterojunction solar cells, a thin intrinsic amorphous-silicon (a-Si:H) buffer layer between a doped emitter and a c-Si wafer is essential to minimize carrier recombination. This study examines the effect of H2 dilution on the properties of the intrinsic a-Si:H layers deposited on Si wafers by plasma-enhanced chemical vapor deposition. A H2/SiH4 ratio of 2∼4 led to improvements in the quality of intrinsic a-Si:H films and in the performance of passivation compared to a-Si:H film without H2 dilution. A high H2-dilution ratio, however, degraded the passivation of the a-Si:H film. The Si heterojunction solar cells with an optimal intrinsic a-Si:H layer showed an efficiency of 12.3%.