ELECTRICAL AND OPTICAL-PROPERTIES OF CUGATE2

The electrical and optical properties of CuGaTe2 single crystals were investigated by resistivity and Hall effect measurements in the temperatur range T = 77… 300 K and optical transmission measurements in the temperature range T = 20… 300 K at photon energies hν = 1.15…1.50 eV. All samples were p‐type conducting due to shallow acceptors with ionization energies EA1 ≈ 10−3 eV and concentrations NA1 ≈ p = (2…4). 1018 cm−3. The absorption spectra could be described by simultaneous consideration of acceptor ‐ to ‐ conduction band transitions with EA2 = 360 meV and NA2 ≈ 1022 cm−3 and valence band ‐ to ‐ conduction band transitions with EG = 1.24 eV at room temperaure. The temperature coefficient of the fundamental edge is dEG/dT = −4.0. 10−4 eV/K. The results are discussed with regard to some general trends found in the Cu‐III–VI2 compounds. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim