Low-temperature current–voltage characteristics of MIS Cu/n-GaAs and inhomogeneous Cu/n-GaAs Schottky diodes

Abstract

The current–voltage (I–V) characteristics of metal–insulating layer–semiconductor Cu/n-GaAs and inhomogeneous Cu/n-GaAs Schottky barrier diodes were determined in the temperature range 80– 300 K . The evaluation of the experimental I–V data reveals a nonlinear increase of the zero-bias barrier height ( qΦ 0) for the inhomogeneous Cu/n-GaAs Schottky barrier diodes and a linear increase of the zero-bias barrier height ( qΦ 0) for Cu/n-GaAs Schottky barrier diodes with an interfacial layer. The ideality factor n decreases with increasing temperature for all diodes. Furthermore, the changes in Φ 0 and n become quite significant below 150 K and the plot of ln( I 0/ T 2) versus 1/ T exhibits a non-linearity below 180 K for the inhomogeneous barrier diodes. Such behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. The value of the Richardson constant was found to be 5.033 A/ cm 2 K 2 , which is close to the theoretical value of 8.16 A/ cm 2 K 2 used for the determination of the zero-bias barrier height.