Electronic properties of Cu2(Zn, Cd)SnS4 determined by the high-field magnetotransport

Abstract

Resistivity, ρ ( T ), and magnetoresistance (MR) are investigated in the Cu _2 Zn _1− _x Cd _x SnS _4 single crystals for compositions x ≡ Cd/(Zn + Cd) = 0.15–0.24, in the temperature range of T ∼ 50–300 K in pulsed magnetic fields of B up to 20 T. The Mott variable-range hopping (VRH) conductivity is established within wide temperature intervals lying inside Δ T _M ∼ 60–190 K for different x . The deviations from the VRH conduction, observable above and below Δ T _M , are connected to the nearest-neighbor hopping regime and to the activation on the mobility threshold of the acceptor band (AB) with width W ≈ 16–46 meV. The joint analysis of ρ ( T ) and positive MR permitted determination of other important electronic parameters. These include the localization radius, α ≈ 19–30 Å, the density of the localized states, g ( μ ) ≈ (1.6–21) × 10 ^17 meV ^−1 cm ^−3 at the Fermi level μ , and the acceptor concentration, N _A ∼ (6–8) × 10 ^19 cm ^−3 , for various x and in conditions of different vicinity of the investigated samples to the metal–insulator transition. In addition, details of the AB structure, including positions of μ and of the mobility threshold, E _c , are found depending on the alloy composition.

Keywords

• semiconductors
• Cu2(Zn, Cd)SnS4
• electrical transport
• disordered systems
• magnetoresistance
• high magnetic fields