Nature of electrical transport properties of nanocrystalline ZnIn₂Se₄ thin films

Highlights: • Annealed film of ZnIn₂Se₄ has a homogenous nature with smaller roughness. • ZnIn₂Se₄ film showed conduction mechanisms with ΔE₁ = 0.44 eV and ΔE₂ = 0.65 eV. • Thermoelectric measurements showed a n-type polarity of ZnIn₂Se₄ thin films. • J–V characteristics for Al/ZnIn₂Se₄/Al structure reveals three distinct regions. • The trap-filled-limited voltage (V_TFL) decreased with increasing temperature. - Abstract: ZnIn₂Se₄ thin films were deposited on glass substrates by thermal evaporation technique. Some of ZnIn₂Se₄ films were annealed under vacuum at 623 K for 2 h. Atomic force microscope (AFM) images were analyzed for as-deposited and annealed films. The roughness degree of the film surface decreased under the influence of annealing. DC Electrical conductivity studied as a function of temperature. Two activation energies were determined that ΔE₁ = 0.44 eV and ΔE₂ = 0.65 eV. Using thermo-electric measurements, the thermoelectric power factor (P), carrier concentration (n) and mobility (μ) were calculated. Current density–voltage characteristics of Al/ZnIn₂Se₄/Al sandwich structure were examined. Different mechanisms were obtained; ohmic conduction mechanism at lower voltages and space charge limited conductivity (SCLC) mechanisms at higher voltages.