Simulation of the reverse I–V characteristics of the Schottky barrier radiation detector structures prepared on semi-insulating GaAs

Abstract

The reverse current–voltage (I–V) characteristics of the Schottky barrier radiation detector structures prepared on semi-insulating gallium arsenide (SI GaAs) have been simulated using a modified thermionic field emission (TFE) model. In order to explain the charge–current transport, the effect of tunnelling and thermionic field emission together with the Schottky barrier lowering were considered taking into account the voltage drop on the quasi-neutral bulk region. The modified TFE model describes reverse I–V characteristics in the temperature range between 300 K and 360 K. An observed agreement between measured and simulated characteristics enabled us to determine the Schottky barrier height and specific resistance of the SI GaAs base from the theoretical simulation. The results of calculated resistivities are compared with resistivities determined by the van der Pauw method. The value of the Schottky barrier height is in good agreement with the previously published data. A much higher value of the calculated ohmic current compared to the current corresponding to the diode structure at a low bias/current region is revealed. A detected difference increases with increasing temperature. This fact led us to conclude that the current in the linear part of the I–V characteristics in the low bias region does not correspond to the ohmic transport, being linear; that is, in contradiction with the more generally considered view.