Schottky Barrier Height Inhomogeneity of Ti/n-GaAs Contact Studied by the I-V-T Technique

The current-voltage characteristics of Ti/n-GaAs Schottky diodes measured over a temperature range of 78 to 299 K have been interpreted on the basis of thermionic emission across an inhomogeneous Schottky contact. The experiment shows that the apparent barrier height (Ф_ap) increases from 0.437 eV at 78 K to 0.698 eV at room temperature. The plot of Ф_ap versus 1/T does not exhibit a simple linear relationship over the whole temperature range, indicating that the barrier height distribution is more complicated than the frequently observed single Gaussian distribution. A new multi-Gaussian distribution model is developed. Our experimental results can be explained by a double Gaussian distribution of the barrier heights. The weight, the mean barrier height, and the standard deviation of the two Gaussian functions are 0.00001 and 0.99999, 0.721 and 0.696, 0.069 and 0.012eV, respectively.