Analysis of anomalous transport mechanism across the interface of Ag/p-Si Schottky diode in wide temperature range

Abstract

We have investigated the detailed temperature dependent mechanism across the interface formed in Ag/p-Si Schottky diode. The Schottky diodes were fabricated by depositing highly pure silver and aluminum metals on the front and back sides of the boron doped p-type semiconductor to form the Schottky and ohmic contacts respectively. The fabricated diode clearly illustrates the rectifying properties between 80 K and 300 K temperature range due to the interface band discontinuity and formation of depleted region. According to thermionic emission diffusion theory the transport mechanisms across the interface reveals abnormal increase in potential barrier and decrease in ideality factor with increase in the temperature due to the potential fluctuations and spatial inhomogeneities at the interface. The inhomogeneities at the interface possess the Gaussian distributions of barrier heights having mean experimental barrier height (ϕ¯b0), 0.91 eV and standard deviation (σ), 0.11 eV respectively. The mean barrier height (ϕ¯b0) of 0.93 eV and Richardson,s coefficient (A∗∗) of 2.7 × 105 Am−2K−2 were obtained from the modified activation energy plot. The Richardson's constant, 2.7 × 105 Am−2K−2 is of the order of known theoretical value of 3.2 × 105 Am−2 K−2 for p-Si. The existence of interface states decreases the capacitance with decrease in the temperature at each applied bias voltage. The higher value obtained for barrier height from CV analysis in comparison to that IV analysis is due the existence of tunneling factor and barrier inhomogeneities. The parameters which characterize the interfacial region were also calculated from CV analysis and found to vary with temperature. The obtained results showed that the fabricated Schottky diode may be a good candidate in the electronic devices.