Quantitative correlation of high quality a-Si:H p-i-n solar cell characteristics with properties of the bulk and p/i interface region

Studies have been carried out on high quality hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells with protocrystalline i-layers to establish the nature of p/i interfaces and to quantify their contributions to various solar cell characteristics. The p-a-SiC:H,B/i-a-Si:H/n-μcSi:H,P cell structures used had the a-Si:H i-layers deposited from hydrogen diluted silane with R≡[H₂ ]/[SiH₄]=10. The high quality p/i interface regions obtained with R=10, indicated by the high and stable open circuit voltage (V_oc) values, were further improved by increasing R in the 200 Å of a-Si:H adjacent to the a-SiC:H layer. From the systematic improvement and ability to obtain p/i interface regions with outstanding quality, it was possible to track their contributions to cell characteristics relative to those from the bulk. Results of dark current voltage (J_D-V) and short circuit current-open circuit voltage (J_sc-V_oc) characteristics are presented which clearly demonstrate that even high quality interface regions in p-i-n cells can mask some contributions of protocrystalline bulk layers. Results are also presented and discussed on how the relative contributions of bulk and p/i interfaces can be isolated and quantified so they can be used as inputs for reliable analysis of solar cell characteristics