The Effect of ZnO:Al Sputtering Condition on a-Si:H / Si Wafer Heterojunction Solar Cells
A-Si:H/Si wafer heterojunction solar cells with different ZnO:Al sputtering conditions were fabricated and the effects of sputtering conditions on device performance were evaluated. Various sputter condition(substrate temperature RT~200’C, working pressure 0.5mTorr~15mTorr, thickness 60~100nm) were tested and optimized as 130’C, 0.5mTorr, 80nm by measuring reflectance and sheet resistance of ZnO:Al layer on corning glass. However, when optimal ZnO:Al condition was applied to solar cells, series resistance was high which led to device efficiency ~10%. Dark I-V curves of with and w/o ZnO layer showed large difference, which means there is a kind of barrier to current flow between ZnO:Al and a-Si:H layer. Modified condition with double layer scheme was applied and lower series resistance and device efficiency above 12% could be reached. The improvement may be due to either suppression of Si oxide formation or less defect formation by impinging atoms.
Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park
S. K. Kim et al., "The Effect of ZnO:Al Sputtering Condition on a-Si:H / Si Wafer Heterojunction Solar Cells", Solid State Phenomena, Vols. 124-126, pp. 1015-1018, 2007