Exclusively Thermal Donor-doped Cz Wafers for Silicon Heterojunction Solar Cell Technology

In this paper, a first evaluation of the compatibility between thermal donor-doped Czochralski silicon and the hydrogenated amorphous Silicon/crystalline Silicon heterojunction technology, is presented. The wafers resistivity was adjusted thanks to the controlled thermal donors generation through 450 °C anneals of calculated durations, following a model detailed in this paper. Minority carrier lifetimes higher than 2 milliseconds, matching the requirements of the heterojunction technology used, were demonstrated. The solar cells were manufactured and efficiencies comparable to cells based on “high quality” Float-Zone substrates were obtained. The stability of the solar cells performances under illumination and temperature was also assessed, and revealed no degradation of the bulk quality even after prolonged illumination.