Study on the fabrication of n-type CuAlSe2 thin films

Chalcopyrite semiconductors with large band gap are generally p-type and the realization of n-type materials has been found difficult. CuAlSe2, with a band gap of 2.68 eV, is one of these compounds. Up to now, the n-type has only been obtained on Zn-doped single crystals. In the present work we describe a different way used to try to achieve n-type CuAlSe2. Thin films of CuAlSe2 have been doped by Au/K, Zn, Cd. The films have been characterized by electrical measurements but also by X-ray diffraction, electron probe microanalysis, optical measurements, photoluminescence and X-ray photoelectron spectroscopy. It is shown by the hot probe technique that annealing for half an hour at 823 K doped films can be allowed achieve polycrystalline n-type CuAlSe2. However, if we succeeded in incorporating the doping element Cd, Zn and K, the n-type conductivity was not systematically achieved. (C) 2003 Elsevier Science B.V. All rights reserved.