Electrical and optical properties of CuGaTe 2

The electrical and optical properties of CuGaTe 2 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 E A1 ≈ 10 −3 eV and concentrations N A1 ≈ p = (2…4). 10 18 cm −3 . The absorption spectra could be described by simultaneous consideration of acceptor ‐ to ‐ conduction band transitions with E A2 = 360 meV and N A2 ≈ 10 22 cm −3 and valence band ‐ to ‐ conduction band transitions with E G = 1.24 eV at room temperaure. The temperature coefficient of the fundamental edge is dE G /dT = −4.0. 10 −4 eV/K. The results are discussed with regard to some general trends found in the Cu‐III–VI 2 compounds.