Development of a Polysilicon Emitter Solar Cell

Abstract

Solar cells with emitters consisting of a very thin (<20 nm) layer of polysilicon overlaid with a thicker (70–130 nm) layer of recrystallized amorphous silicon have been fabricated and characterized. Both layers were formed by LPCVD with heavy in-situ phosphorus doping. The highest temperature used in processing was the 650°C recrystallization anneal for the amorphous material. Short circuit current densities of 30 mAcm^-2 combined with fill factors close to 0.8 have been achieved under simulated 100 mWcm^-2 AM1.5 illumination. Open-circuit voltages as high as 669 mV at 28°C were obtained for cells formed on high quality 0.1 Ω cm float zone substrates when J_SC was set to 32 mAcm^-2. Total-area AM1.5 efficiencies were up to 14%.