About the nature of the barrier inhomogeneities at Au/Ti/n-InAlAs(001) Schottky contacts

Abstract

A correlation study of InAlAs surface morphology by atomic force microscopy and a study on the temperature (78–380 K) dependence of Au/Ti/InAlAs(001) Schottky barriers' current-voltage characteristics were performed. It is shown that a change in the growth structural defect (pit) density on the InAlAs surface from 106 to 107 cm−2 practically does not affect the current-voltage dependence at temperatures above 200 K that is well described by the thermionic emission theory with the ideality factor and the barrier height close to 1.1 and 0.69 eV, respectively. At the same time, change in the pit density has a significant effect on the Schottky barrier parameters at temperatures below 200 K, which can be explained by the Tung model suggesting the presence of local inhomogeneities with a lower barrier height and different total occupied areas. Also, the areas at the pit defect periphery that can lead to effective barrier height lowering after the Schottky contact formation were revealed by Kelvin probe force microscopy. Based on the obtained data, it can be concluded that the growth defects on the InAlAs surface shaped as pits cause areas in Schottky contact with a lower barrier height.