Analysis of current-voltage characteristics of Al/p-ZnGa₂Se ₄/n-Si nanocrystalline heterojunction diode

The polycrystalline ZnGa₂Se₄ thin film was prepared by thermal evaporation technique on n-Si wafer followed by annealing at 700 K. Then, the Al/p- ZnGa₂Se₄/n-Si/Al heterojunction diode was fabricated. XRD pattern shows that the annealed ZnGa₂Se₄ film has a polycrystalline structure. AFM images indicate that the ZnGa ₂Se₄ film is formed of nanoparticles. The dark current-voltage characteristics of the heterojunction diode at various temperatures have been investigated to determine the electrical parameters and conduction mechanism. The Al/p-ZnGa₂Se₄/n-Si/Al diode shows a rectification ratio of 2.644 × 10² at ±2 V at room temperature. It was found that at forward bias voltages ≤0.5 V, the conduction mechanism of the diode is controlled by the thermionic emission mechanism, while at bias voltages higher than 0.5 V, it is controlled by the space charge limited current mechanism. The series resistance R_s, the ideality factor n and the barrier height φ_b values of the diode are determined by performing different plots from the forward current-voltage characteristics. The reverse current mechanism of the diode is controlled by the carrier generation-recombination process in the depletion region. The obtained results show that the Al/p-ZnGa₂Se₄/n-Si/Al heterojunction is a good candidate for the electronic device applications.