Schottky Diodes and Ohmic Contacts for the III-V Semiconductors

Abstract

In this chapter a review of the electrical properties of metal-semiconductor contacts to the III-V semiconductors is given. Metal-semiconductor structures play an important role in devices based on the III-V compound semiconductors in the form of Schottky-barrier diodes or ohmic contacts. Important III-V devices utilizing Schottky-barrier junctions include solar cells, microwave mixer diodes, and metal semiconductor field-effect transistors (MESFETs) and their associated integrated circuits. Schottky diodes also find widespread use for III-V semiconductor materials characterization, including carrier concentration profiling and deep-level identification. Ohmic contacts with low resistance are necessary for high performance in many III-V devices. For example, the efficiency of light-emitting diodes and lasers is strongly influenced by contact resistance, and the noise behavior and the gain of an FET are significantly affected by the character of ohmic contacts. In all of these cases, the metal-semiconductor interface is formed on a chemically etched, as compared to an atomically clean, semiconductor surface. Thus, in this chapter the properties of Schottky diodes and ohmic contacts prepared by chemically etching the III-V semiconductors are emphasized, while the previous chapter dealt with metal-semiconductor interface formation on atomically clean surfaces.