Study on P-a-Si:H properties of N-type heterogeneous junction solar cells manufactured by large-area parallel plate PECVD machine

P-type hydrogenated amorphous silicon (P-a-Si:H) plays an important role in heterojunction solar cells. On the one hand, P-a-Si:H processed by plasma enhanced vapor deposition (PECVD) can selectively collect carrier holes on the rear of N-type silicon based heterojunctions with intrinsic thin layer (HJT) solar cells (in this article, the back ride of the cell is P-a-Si:H); On the other hand, the ohmic contact between P-a-Si:H and conductive ITO film is beneficial for hole transport. Therefore, the performance of P-a-Si:H has very significant impact on the property of HJT solar cells. The electrical conductivity, impurity activation energy, and passivation performance of silicon wafer surface are the core performance indicators of P-a-Si:H materials themselves. In this paper, we systematically research the optimal RF power density, doping concentration (diborane doped), hydrogen dilution ratio and plate spacing for the growth process of P-a-Si:H using a self-developed large-area parallel plate PECVD equipment (Jincheng Machine). The results show that the P-a-Si:H has an electrical conductivity of 1.27 × 10−3 S/cm and an activation energy of 251 meV, and the maximum mass production efficiency of the HJT solar cell is 25.21%, Voc is 741 mV and Jsc is 41.57 mA/cm2.