Chemical incorporation of copper into indium selenide thin films

Indium selenide thin-films have been treated in a copper-containing chemical bath with the goal of forming a precursor layer capable of being converted into copper indium diselenide. The conversion process was carried out by annealing the layers in a tube furnace in the presence of selenium vapour. The phase content of the layers as a function of composition and annealing temperature has been investigated by Raman spectroscopy. It is concluded that copper selenide is formed during the chemical bath treatment and that during annealing the copper selenide reacts first with elemental selenium vapour and then with the indium selenide to form chalcopyrite CuInSe2. Secondary phases of CuIn3Se5 and Cu-Au ordered CuInSe2 have been detected in annealed copper-poor layers.