Interpretation of the I–V , C–V and G/ω-V characteristics of the Au/ZnS/n-GaAs/In structure depending on annealing temperature

The Zinc Sulphide (ZnS) thin film, which is included in the Au/n-GaAs/In diode as the interface layer, was grown on the n-GaAs semiconductor substrate by the spray pyrolysis method. First, to reveal some structural, surface and optical properties of the ZnS thin film, XRD, SEM and absorption measurements were taken. It was determined that the ZnS thin film completely covering the surface of the n-GaAs semiconductor substrate has a hexagonal structure and a forbidden energy range of 3.83 eV. Later, the current-voltage ( I–V), the capacitance-voltage ( C–V) and the conductance-voltage ( G/ω-V ) measurements of the Au/ZnS/n-GaAs/In structure were taken at room temperature, and various important parameters of the structure were calculated with different methods. In order to reveal the effects of annealing temperature on the I–V, C–V and G/ω-V measurements of Au/ZnS/n-GaAs/In structure, the device was annealed at 100, 200 and 300 °C respectively for 5 min in nitrogen gas environment. The characteristic parameters were calculated again and the results were interpreted comparatively. At the same time, with the help of the C–V and G/ω-V characteristics, the dependence on applied bias voltage and frequency of the parameters such as dielectric constant, dielectric loss, loss tangent, ac electrical conductivity and real and imaginary part of electric modulus of the diode have been revealed. After thermal annealing at 200 °C, it has been determined that the ideality factor, turn-on voltage and leakage current values are at minimum level and the barrier height and rectification ratio values are at maximum level. In other words, it has been revealed that the optimum thermal annealing temperature for this device is 200 °C.