Influence of nanostructure Fe-doped ZnO interlayer on the electrical properties of Au/n-type InP Schottky structure

The Au/Fe-doped ZnO/n-InP metal/interlayer/semiconductor (MIS) Schottky structure is fabricated with Fe-doped ZnO nanostructure (NS) as an interlayer. The field emission scanning electron microscopy and atomic force microscopy results demonstrated that the surface morphology of the FeZnO NS on n-InP is fairly smooth. The x-ray diffraction results reveal that the average grain size of the FeZnO film is 12.35 nm. The electrical properties of the Au/n-InP metal-semiconductor (MS) and Au/FeZnO NS/n-InP MIS Schottky structures are investigated by current-voltage and capacitance-voltage measurements at room temperature. The Au/FeZnO NS/n-InP MIS Schottky structure has good rectifying ratio with low-leakage current compared to the Au/n-InP MS structure. The barrier height obtained for the MIS structure is higher than those of MS Schottky structure because of the modification of the effective barrier height by the FeZnO NS interlayer. Further, the barrier height, ideality factor and series resistance are determined for the MS and MIS Schottky structures using Norde and Cheung's functions and compared to each other. The estimated interface state density of MIS Schottky structure is lower than that of MS Schottky structure. Experimental results revealed that the Poole-Frenkel emission is the dominant conduction mechanism in the lower bias region whereas Schottky emission is the dominant in the higher bias region for both the Au/n-InP MS and Au/FeZnO NS/n-InP MIS Schottky structures.