A method for the deposition of CdTe layers at very low substrate temperatures

In this paper we present an evaporation concept which enables access to very low substrate temperatures for the fabrication of CdTe solar cells at promising solar cell efficiencies. CdTe layers were deposited at substrate temperatures of 300 °C to 190 °C and processed to solar cells with efficiencies of about 12% and 9%, respectively. A further reduction of the substrate temperature abruptly results in non-working solar cells. That effect is discussed in terms of the morphology of the absorber layers. The corresponding solar cell characteristics are compared to cells which were prepared by the conventional close space sublimation method.

► We developed a method for the deposition of CdTe layers at very low temperatures. ► The device has similar evaporation characteristics as conventional devices. ► Solar cells with good efficiencies are prepared at very low substrate temperatures. ► At substrate temperatures of less than 190 °C the efficiencies abruptly vanish. ► The presented concept is easily applicable to an industrial scale.