Electrical, structural, morphological and photovoltaic properties of Au/n-Ge heterojunctions using V₂O₅ interfacial layer

Influence of vanadium pentoxide (V₂O₅) interfacial layer on electrical, structural, morphological and photovoltaic properties of the Au/V₂O₅/n-Ge Schottky diodes is presented. The analysis of morphological properties of the V₂O₅ thin films on the n-Ge surface using AFM and FESEM with EDS reveals the films are homogeneous. The AFM measurements of V₂O₅ thin films show a fairly smooth surface with RMS roughness of 2.44 nm. Further, the FESEM with EDS measurements of the V₂O₅/n-Ge layers evidenced with V, O and Ge elements signifies the presence of V₂O₅ thin films on the n-Ge substrate. The structural properties of V₂O₅ deposited on the n-Ge substrate were studied from XRD and Raman measurements. These properties of V₂O₅ films reveal that the films were highly crystalline with orthorhombic structure and significant diffraction intensity corresponds to V₂O₅ with various crystal orientations. The electrical properties of the n-Ge heterostructure were studied with and without V₂O₅ thin interlayer. The Schottky barrier parameters such as barrier height and shunt resistance seem to be superior for the V₂O₅/n-Ge heterojunction compared to without V₂O₅ interlayer. The current conduction mechanism of the V₂O₅/n-Ge heterojunction signifies SCLC current transport process assisted with traps is found to be dominant at the V₂O₅–Ge interface preferably at large forward bias voltages. Frequency-dependent capacitance and series resistance of the V₂O₅/n-Ge heterojunction and Au/Ge junction are presented. The photovoltaic property of heterojunction was studied under illumination at 100 mW cm⁻² and the studies show a responsivity of 534 mA W⁻¹ at –1 V. In view of these observations, the V₂O₅ interlayer has demonstrated its effectiveness in tuning the barrier characteristics of metal-Ge Schottky junctions. Its photoresponse to illumination also makes its suitability in solar cell of photovoltaic applications.