Optical properties of copper indium diselenide near the fundamental absorption edge

Abstract

In this work we report on an optical absorption study near the band gap of n-type ${\mathrm{CuInSe}}_{2}$ at 7 K. From the analysis of the results the energy gap is found to be 1.02\ifmmode\pm\else\textpm\fi{}0.01 eV. The binding energy of the exciton and the ionization energy of acceptors and donors are determined to be 18, 54, and 26 (\ifmmode\pm\else\textpm\fi{}5) meV, respectively. It is suggested that ${\mathrm{In}}_{\mathrm{Cu}}$ antisite donors and ${V}_{\mathrm{Cu}}$ acceptors are the predominant active intrinsic defects in ``In-rich'' ${\mathrm{CuInSe}}_{2}$.