Defect states assisted charge conduction in Au/MoO_3–x/n-Si Schottky barrier diode

Role of defect states of thermally evaporated molybdenum trioxide (MoO_3−x) on electrical conductivity was investigated via low temperature current–voltage and capacitance–voltage measurements. To clarify the charge transport phenomena through MoO_3−x, a 15 nm thin layer of MoO_3−x film was used as an interface layer between gold and n-type Silicon (n-Si). The formation of an interface dipole between n-Si and MoO_3−x exhibits a rectifying behaviour of Au/MoO_3−x/n-Si Schottky barrier diode (SBDs). The rectifying nature of the SBDs shown up to 175 K due to proper electron extraction from valence band to conduction band via the defect states; however at ≤165 K the rectifying nature was not observed due to insulating behaviour of MoO_3−x layer. Oxygen deficiency as a formation of defects was determined by x-ray photoelectron spectroscopy (XPS). Consequences of these defects as a function of current conduction across the MoO_3−x was also confirmed by low temperature photoluminescence (PL)measurement. (paper)