T. Nishi, Y. Katsumata, K.Sato and H. Miyake*

Tokyo University of Agriculture &Technology, *Mie University
Tel & Fax: +81 42 3887432 / e-mail: takawou@cc.tuat.ac.jp

Abstract
Electron spin resonance (ESR) and Photoluminescence (PL) spectra of CuGaSe₂ single crystals were measured to elucidate defect properties in this compound. A narrow isotropic ESR line with the bandwidth of 0.9 mT and the g-value of 2.006 was observed at 4 K. The intensity of the signal increased by an H₂-annealing and decreased by an O₂ annealing, from which the signal was assigned to that of an electron trapped by the Se-Vacancy (V_Se). A PL signal due to V_Se was observed, which disappeared by the O₂-annealing. Both ESR and PL measurements suggest the presence of a V_Se defect in the CuGaSe₂ single crystals. Another unidentified signal was observed in ESR spectrum and was associated with a Fe-center, taking into account the strong angular dependence of the signal. Keyword: electron spin resonance (ESR), photoluminescence (PL), Se-vacancy, annealing, CuGaSe₂ ;