Hall effect, space-charge limited current and photoconductivity measurements on TlGaSe2 layered crystals

Abstract

TlGaSe2 layered crystals are studied through dark electrical conductivity, Hall mobility, space-charge limited current and illumination- and temperature-dependent photoconductivity in the temperature ranges 120–350 K, 220–350 K, 260–350 K and 120–350 K, respectively. The Hall effect measurements revealed the extrinsic p-type conduction. The Hall mobility increase with decreasing temperature is limited by the thermal lattice scattering. The space-charge limited current and dark conductivity measurements predicted the existence of a single discrete trapping level located at 330 meV with a trap concentration of (1.4–2.2) × 1013 cm−3. The dark electrical conductivity and photoconductivity measurements reflect the existence of three other energy levels located at 95, 46 and 26 meV at high, moderate and low temperatures, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature of 320 K. The illumination dependence of photoconductivity is found to exhibit sublinear, linear and supralinear recombinations at high, moderate and low temperatures, respectively. The change in recombination mechanism is attributed to the exchange in the behaviour of sensitizing and recombination centres.