Photoacoustic Spectroscopy of Defect States in Etched and Air‐annealed CuInSe₂ Single Crystals

Abstract

Photoacoustic spectra of cleaved, polished and etched, and air-annealed n-type CuInSe, single crystals are measured at different frequencies between 30 and 312 Hz. The spectra related to the bulk of the crystals exhibit five structures due to defects that are also present in p-type crystals. Polishing and etching as well as subsequent air annealing at 100, 200 and 300 "C reveal rather complex changes of the defect equilibrium in the near-surface region of the crystals which include both relative concentration changes of existing defects and creation of new defects. The results for polished and etched crystals correspond to trends expected from etching induced local modifications of the composition and structure as revealed by electron spectroscopies and ion channeling. Air annealing is found to affect all existing defects and to create up to five new defects which cannot be explained in terms of the related point defect model proposed by CAHEN and NOUFI.

Electrical and Optical Characterization of Oxygen doped CuInSe2 Crystals

“…It has also been suggested that the acceptor concentration remains practically unchanged during this process (CAHEN, NOUFI; NOUFI, CAHEN). However, recent electron paramagnetic resonance (PADAM et al) and photoacoustic spectroscopy (ZEGADI et al 1995) studies in this compound indicate that oxygen affects not only the donor but also the acceptor concentrations. In addition, it has also been found (HABA et al) that the incorporation of In 2 O 3 in CuInSe 2 thin films leads to an increase in the ratio of copper to indium atoms.…”