Hydrogenated amorphous silicon (a-Si:H) solar cells are prepared by plasma enhanced chemical vapor deposition (PECVD). Before quenching the solar cells, the short circuit current (Jsc
), open circuit voltage (Voc
), fill factor (F. F.) and conversion efficiency (η) are 17.79 mA/cm2, 0.79 V, 53.29, and 7.49 %, respectively. After thermal quenchine the solar cells from 200°C, Jsc, Voc
, F. F., and η are 18.64 mA/cm2, 0.8 V, 53.79, and 8.02 %, respectively. We investigated the thermal equilibrium processes of each P, I, and N layers. Also, we obtained the dark current-voltage characteristics of a-Si:H solar cells before and after quenching. We analyze the results in terms of the change of the internal electric field in a-Si:H solar cells, caused by the shift of the Fermi level of P layer toward valence band.