THERMAL STABILITY OF MICROWAVE PECVD HYDROGENATED AMORPHOUS SILICON AS SURFACE PASSIVATION FOR N-TYPE HETEROJUNCTION SOLAR CELLS

摘要

Intrinsic hydrogenated amorphous silicon (a-Si:H) as surface passivation is an important part ofheterojunction solar cells. However, the temperatures used for the post-deposition fabrication of the heterojunctionsolar cells are limited by the thermal stability of the a-Si:H. In this work, we investigate the thermal stability of the a-Si:H as surface passivation on n-type wafers by annealing them at various temperatures. The results indicate that theannealing temperature is the main factor that determines the thermal stability, while the annealing time also plays arole. In comparison, the dependence on the deposition temperature is very small and can be neglected. At a givenannealing temperature, the level of degradation before stabilisation can be limited by restricting the annealing time,and stability is reached after two to three hours when the annealing temperature is less than 300°C. At suchtemperatures, the amount of degradation is small, with final effective surface recombination velocities of ～20 cm/s.