Effects of strain on the growth and properties of CuInSe₂ epitaxial films

CuInSe₂ films have been grown on both GaAs(0 0 1) and In_0.29Ga_0.71As pseudo-lattice-matched substrates by solid-source molecular beam epitaxy and the effects of strain on the properties of epitaxial films have been investigated. For CuInSe₂ epitaxial films grown on GaAs(0 0 1), the intensities of excitonic emissions become stronger and the line widths of the predominant defect-related emissions become smaller on increasing the thickness of the films from 0.4 to 2 μm, suggesting that the defect density decreases with the film thickness. Drastic improvements in optical and transport properties have been achieved by using In_0.29Ga_0.71As pseudo-lattice-matched substrates; free-exciton emissions were predominantly observed, indicating that high-quality CuInSe₂ epitaxial films have been grown by controlling the misfit strain between the substrates and the epitaxial films.