Microstructure of hydrogenated amorphous silicon layers studied by Spectroscopic Ellipsometry for the surface passivation in heterojunction solar cells

The defect scatter interval (S_t) of a-Si:H/c-Si interface and void concentration (C_v) of a-Si:H were analyzed by Spectroscopic Ellipsometry (S_E). The passivation performance of a-Si:H layers in SHJ solar cells was not only affected by the conductivity, but more importantly, it was strongly governed by the hydrogen content (C_H) in a-Si:H layers. In addition, the microstructure deduced from SE was in perfect accordance with the results revealed by TEM technique. Then, an implied open circuit voltage (V_oc,i_m) of 732mV was obtained when S_t was about 7fs and CH around 7 at.%.