Effect of Dopant Gas Sources on the Properties of Boron Doped P-a-Si1-XOx:H Films and Their Application to A-Si1-XOx:H Thin Film Solar Cells

Hydrogenated amorphous silicon (a-Si:H) thin-film solar cells offer low-cost production and flexibility, making them promising for renewable energy applications. This study examined the effects of the dopant gases diborane (B₂H₆), trimethyl boron (TMB), and a B₂H₆ + TMB combination on the optical and electrical properties of boron-doped hydrogenated amorphous silicon oxide (p-a-Si_1-xO_x:H) films for window layers in a-Si:H solar cells. Films were fabricated using very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD), optimizing doping concentrations to balance a high optical bandgap (E_opt) and conductivity. TMB-doped films exhibited higher E_opt and better optical properties, while the B₂H₆ + TMB combination improved conductivity and overall performance. Single-junction a-Si_1-xO_x:H cells with mixed-doping window layers achieved superior open-circuit voltage (V_oc), fill factor (FF), and quantum efficiency (QE) compared to cells doped solely with B₂H₆ or TMB. These enhancements were attributed to improved interface quality between the window and absorber layers. The findings highlight the advantages of a mixed-doping approach, which optimizes optical and electrical properties, resulting in more efficient and stable thin-film solar cells. This work provides a pathway for developing high-performance and cost-effective photovoltaic devices.