Amorphous/crystalline silicon heterojunction solar cells via Remote plasma chemical vapor deposition: Influence of hydrogen dilution, RF power, and sample Z-height position

Single heterojunction hydrogenated amorphous silicon/monocrystalline silicon (a-Si:H/c-Si) cells of varying hydrogen dilution ratios, RF power, and sample position with respect to the plasma discharge were fabricated using remote plasma enhanced chemical vapor deposition (RPCVD). Only p-type doped a-Si:H is investigated in this paper, without intrinsic a-Si:H (i-layer) passivation. It was found that a hydrogen dilution ratio, R ≤ 2 is necessary to minimize the degradation of the open-circuit voltage (V_OC). Furthermore, a comparison of the RF power on device performance shows enhancements in cell performance, including approximately ~20 mV improvement in V_OC with 30 W vs. 60 W, which may be attributed to a reduction in ion-bombardment damage. Finally, it was found that a higher sample z-height position (away from plasma glow) yields improvements in J_SC and V_OC of 1.6 mA/cm² and 9 mV, respectively at a low RF power of 7 W. These results suggest that the RPCVD is a potential technology to deliver low plasma damage and improved passivation for Si heterojunction solar cell.