Metal-semiconductor nanojunctions and their rectification characteristics

Junctions of silver-copper oxide and silver-zinc oxide, respectively were prepared within the pores of diameters, 20 nm, in anodic aluminium oxide membranes. Voltage-current characteristics were measured over the temperature range 373–573 K which showed rectification behaviour. Using the standard equation the difference between the work functions of the metal and the semiconductor was calculated. This showed a variation with the temperature of measurement. This is explained as arising due to the effect of pressure generated as a result of thermal expansion of the metallic phases concerned between the electrodes. This is consistent with the theoretical prediction of Fermi level shifting of the semiconductor within the bandgap as a function of pressure.