On the low-temperature photoluminescence and photovoltaic properties of fine-grained CdTe films

In the low-temperature ( T = 4.2 K) photoluminescence spectrum of a fine-grained (the grain size is smaller than 1 μm) obliquely sputtered CdTe thin film, the dominant intrinsic emission band caused by potential barriers at grain boundaries and the edge doublet band representing the LO-phonon replica of the dominant band are observed. Doping of the film with an In impurity quenches the doublet band and subsequent heat treatment activates the intrinsic emission band. The full-width at half maximum and the short-wavelength shift of the red edge of the latter correlate with a maximum anomalously high photovoltage of 2 × 10 2 –10 3 V generated by the film.