On the current conduction mechanisms of WO₃/n-Ge Schottky interfaces

Electrical properties of n-Ge contacts tailored with nanostructured WO₃ is analysed using current-voltage (I-V) and capacitive-voltage (C-V) measurements. Au/WO₃/n-Ge heterostructure show its significant improvement in terms of high forward current and high magnitude of rectification ratio (RR = 3040 at ± 0.5V) than compared to contact without interlayer. The series resistance evaluated using Cheung's method found to be very low (R_s = 17 Ω) in contacts with WO₃ interlayer than compared to pristine sample. The influence of WO₃ interfacial layer in defining the accumulation and inversion regions is clearly observed in the C-V characteristics measured at 1 MHz. A transition from ohmic conduction at low bias voltages to trap charge limited current (TCLC) conduction at high bias voltages is observed in the case of Au/WO₃/n-Ge contacts. The distribution of traps or defects at the oxide-Ge interface possibly associated to the observed current conduction mechanisms at high bias regions. Very low series resistance, high rectification ratio and high forward currents of Au/WO₃/n-Ge contacts show its applicability in optoelectronic and photovoltaic applications.