The effects of P-layer thickness on photovoltaic properties of PIN-type homojunction and P(a-SiC:H)IN-type heterojunction solar cells have been investigated. The samples were prepared by RF glow discharge decomposition of silane hydrogen mixtures, and the window layers in heterojunction solar cells were deposited by the plasma decomposition of $SiH_4 + (CH_4)_2 + (B_2H_6)_{0.01} + (H_2)_5$.
The optimum P-layer thickness in homojunction and heterojunction solar cells are 100 and 80 Å, respectively. The absorption in P-layer in homojunction solar cells is a dominant factor to decrease the conversion efficiency, however, in heterojunction solar cells the series resistance of P-layer is the most important factor to determine the conversion efficiency.
At the present stage of experiments, open circuit voltage of 0.883 V, fill factor of 59.2%, short circuit current density of 10.6 mA/㎠, and conversion efficiency of 6.93% have been obtained under 80 mW/㎠ sunlight.
