Electrical and carrier transport properties of the Au/Y₂O₃/n-GaN metal-insulator-semiconductor (MIS) diode with rare-earth oxide interlayer

The electrical and transport properties of rare-earth Y₂O₃ on n-type GaN with Au electrode have been investigated by current–voltage and capacitance–voltage techniques at room temperature. The Au/Y₂O₃/n-GaN metal-insulator-semiconductor (MIS) diode shows a good rectification behavior compared to the Au/n-GaN metal–semiconductor (MS) diode. Statistical analysis showed that a mean barrier height (BH) and ideality factor are 0.78 eV and 1.93, and 0.96 eV and 2.09 for the Au/n-GaN MS and Au/Y₂O₃/n-GaN MIS diodes, respectively. Results indicate that the high BH is obtained for the MIS diode compared to the MS diode. The BH, ideality factor and series resistance are also estimated by Cheung’s function and Norde method. From the forward current–voltage data, the interface state density (N_SS) is estimated for both the MS and MIS Schottky diodes, and found that the estimated N_SS is lower for the MIS diode compared to the MS diode. The results reveal that the introduction of Y₂O₃ interlayer facilitated the reduction of N_SS of the Au/n-GaN interface. Experimental results suggest that the Poole–Frenkel emission is a dominant conduction mechanism in the reverse bias region of both Au/n-GaN MS and Au/Y₂O₃/n-GaN MIS diodes.