Interface states density distribution in Au/n-GaAs Schottky diodes on n-Ge and n-GaAs substrates

The current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Au/n-GaAs Schottky diodes on n-Ge substrates are investigated and compared with characteristics of diodes on GaAs substrates. The diodes show the non-ideal behavior of I–V characteristics with an ideality factor of 1.13 and barrier height of 0.735 eV. The forward bias saturation current was found to be large $(3 \times 10^{-10} A$ vs. $4.32 \times 10^{-12} A)$ in the GaAs/Ge Schottky diodes compared with the GaAs/GaAs diodes. The energy distribution of interface states was determined from the forward bias I–V characteristics by taking into account the bias dependence of the effective barrier height, though it is small. The interface states density was found to be large in the Au/n-GaAs/n-Ge structure compared with the $Au/n-GaAs/n^+$-GaAs structure. The possible explanation for the increase in the interface states density in the former structure was highlighted