OPTICAL INVESTIGATION OF DEFECTS IN P-TYPE CUINSE2 SINGLE-CRYSTALS

Optical absorption spectra in the photon energy range from 0.03 to 1.1 eV and photoreflectance spectra in the range of the fundamental edge are measured on p-type CuInSe2 single crystals. Besides a dominant con tribution to the absorption coefficient due to intervalence band trans itions below about 0.75 eV the spectra revealed five additional struct ures that can be ascribed to defect induced optical transitions with c haracteristic energies between 0.48 and 0.72 eV. Based on a comparison of the near-edge optical absorption and photoreflectance spectra a sh allow defect (donor or acceptor) with an ionisation energy of about 46 meV was identified.