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 x 10(-10) A vs. 4.32 x 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. (C) 2001 Published by Elsevier Science B.V.