Detailed experimental and theoretical analysis of the high-temperature current conduction properties of Er-doped TiO2 thin film based diodes

Abstract

The high-temperature (303 K to 413 K) current conduction properties of Au/TiO2/p-Si (undoped) and Au/Er: TiO2/p-Si (doped) Schottky barrier diodes (SBDs) were analyzed. The barrier height (Фb0) increased, whereas the ideality factor (n) and series resistance (RS) decreased for these devices with increasing temperature. The activation energy as well as Richardson constant (A*) were determined from the temperature-dependent Richardson plot (R-plot). The calculated values of A* are much lower than the reported value. This behavior was clarified by assuming the barrier inhomogeneities and considering a Gaussian distribution (GD) of barrier height (BH). GD analysis modified the R-plots. The estimated standard deviation (σ0) value decreased from 0.18 (for undoped) to 0.17 (for the doped device), which indicates the reduction in barrier inhomogeneity. Also, the calculated mean values of Фb0 and A* are 1.41 eV and 871 A/(cm2 K2 ) for undoped, 1.46 eV and 402 A/(cm2 K2 ) for the doped device, respectively. The values of A* are much closer to the reported value of 671 A/(cm2 K2 ) for TiO2. Therefore, it is evident that this analysis using the thermionic emission (TE) theory and considering a GD of BH elucidated the I–V characteristics of the SBDs. Other device parameters like bandgap variation with temperature, carrier concentration, Fermi energy, and RC constant were theoretically determined. Further, a unique technique has been developed to calculate the interface trap density profiles using the I–V characteristics of the devices. Hence, it is manifested that the temperature-dependent I–V characteristic can be used as a robust tool to analyze all possible vital parameters of the device.