The effect of Se content on defect levels in CuInSe/sub 2/ single crystals detected by photoacoustic spectrometry

摘要

The objective of this paper is to investigate the impact of changes in the selenium content of thin-film solar cell CuInSe/sub 2/ single crystals on their optical properties in the subgap region of the infrared spectrum. A high resolution near-infrared photoacoustic spectrometer of the gas-microphone type is used for room temperature analysis of nonradiative defect states in as-grown n and p-type CIS crystals. Samples with an excess and a deficiency of Se (5% off the stoichiometric composition), were grown from the melt by the vertical Bridgman technique. The absorption coefficient has been derived from photoacoustic spectra in order to establish activation energies for several defect-related energy levels.