Understanding hole transport across amorphous Si passivation layers in Si heterojunction solar cells using Monte Carlo simulation

Passivation layers based on hydrogenated amorphous silicon (a-Si:H) have enabled silicon heterojunction solar cells to achieve high fill factors and conversion efficiencies. Traditionally, intrinsic a-Si:H(i) provides passivation between the doped a-Si and c-Si. However, studies have shown that there is a 2mA/cm(2) optical loss associated with this layer. In this paper we explore the option of using a-SiOx:H(i) as a passivation layer as oxygen can used to create a passivation layer with a wider bandgap. We utilize an in-house kinetic Monte Carlo solver to simulate defect assisted transport across the heterointerface and the passivation layer. Our simulations show a strong correlation between multi-phonon transitions and overall device performance.