Single-phase control of CuTe thin films for CdTe solar cells

Phase control is important to obtain high-performance CdTe solar cells when copper telluride is used as a back-contact for CdTe solar cells. In this paper single-phase CuTe was mainly controlled by the Cu/Te ratio via a co-evaporation method in combination with rapid thermal processing treatments. The alloy thin films as-deposited were mainly amorphous. After thermal treatments, the films experienced the phase transformation from mixed phases of CuTe and Cu1.4Te to single phase CuTe and then to coexisting phases. Single phase CuTe thin films were p-type semiconductor compounds and had a high carrier concentration, ∼1021 cm−3. With the copper telluride buffer layer, device performance than those without the buffer layer has been obtained. Moreover, single-phase orthorhombic CuTe contact buffer layer obviously improved diode characteristics and enhanced the device performance.