Modification of interface properties of Au/n-GaN Schottky junction by rare-earth oxide Nd₂O₃ as an interlayer and its microstructural characterization

We demonstrate the impact of rare-earth Nd₂O₃ interlayer on the electrical properties of Au/n-GaN Schottky junction (SJ), the Au/Nd₂O₃/n-type GaN metal/interlayer/semiconductor (MIS) junctions were prepared and characterized. X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to analyze the structural properties of the deposited Nd₂O₃ films on the n-GaN surface. Results confirmed that the Nd₂O₃ layer was formed on the n-GaN surface. The MIS junction electrical results are compared with the Au/n-GaN Schottky junction (SJ) results. Electrical outcomes demonstrated that the MIS junction revealed a good rectification behaviuor with a higher barrier height (BH) (0.66 eV) than the SJ (0.59 eV), which indicates the BH is manipulated by the Nd₂O₃ interlayer. The I–V, Cheung's, Ψ_S-V and α(V)–V plots were employed to derive BH and determined that values were similar to one another, demonstrating that the techniques used here are consistent and valid. The capacitance-frequency (C-f) and conductance-frequency (G-f) properties of SJ and MIS junction are assessed in the range of 1 kHz-1 MHz and results demonstrate that the capacitance and conductance are sturdily reliant on frequency. The estimated interface state density (N_SS) of the MIS junction is less than the SJ which shows that the Nd₂O₃ interlayer was responsible to reduces the N_SS. Results demonstrate that ohmic and space charge limited conduction mechanisms in the forward bias of the SJ and MIS junctions. Experimental outcomes established that the Schottky emission directs the reverse current in the SJ. Though, the Poole-Frenkel emission ruled reverse current in the lower bias, while the Schottky emission governs reverse current in the higher bias region of the MIS junction. Findings demonstrate that the Nd₂O₃ layer could be appropriate for the development of MIS/MOS devices.