A photovoltaic study of current transport and its influence on the determination of the Schottky barrier height in Schottky diodes
Current transport processes including thermionic emission, tunnelling and carrier recombination at the Au/n-Si and Au/n-GaAs interfaces are studied by photovoltage measurements in the temperature range 60-300 K. The Schottky barrier heights (SBH) are also determined from the photovoltage measurements at various temperatures, and the influence of these current transport processes on the determination of the SBH is investigated. It is shown that, at room temperature, as the current transport is dominated by the thermionic emission, the SBH obtained is reliable and is in very good agreement with that obtained from our internal photoemission, I-V and C-V measurements. However, as the temperature decreases the contribution of the recombination current increases, and this leads to a decrease of the SBH. This situation is similar to that in the I-V measurements, but such a positive temperature dependence of the SBH conflicts with the results from the C-V and the internal photoemission measurements, which show that the temperature dependence of the SBH in Au/n-Si is almost identical to that of the indirect bandgap in silicon, while the SBH in Au/n-GaAs has no temperature dependence.