Annealing effect on the barrier characteristics and interface properties of Au/Pt/Ti/n-InAlAs Schottky contacts

Abstract

A comprehensive study of the annealing effect (300–400 °С) on the electrical properties, morphology and chemical composition of the Au/Pt/Ti/n-InAlAs interface (Schottky contact) is carried out. It is shown that the Schottky contact pre-annealing during the formation or primary short (∼1 min) annealing significantly increases the barrier height to the standard 0.68–0.7 eV with an ideality factor close to 1.1 due to the formation of a homogeneous amorphous TiAs layer with a small metallic (elemental) indium content. A further annealing at temperatures 300–350 °С for up to 20 min does not lead to significant changes in the morphology and electrical parameters of the Schottky contact. The annealing at the temperature of 400 °С (∼10 min) leads to an increase in the barrier height and the ideality factor to the values of 0.73 and 1.3, respectively. In this case, the formation of an about 20 nm thick TiAs layer and indium clusters shaped as a pyramids at the Ti/InAlAs interface is also observed. Analysis of the temperature dependences of Schottky barrier parameters within the Tung model showed that only structural changes at the interface after the 400 °С annealing lead to a significant increase in the Ti/InAlAs Schottky contact homogeneity, reducing the density of local regions with a lowered barrier height.