Metal - Gan Contact Technology

Abstract

In this talk, we summarize the experimental results obtained on metal-GaN interactions in our laboratory. These interactions include the epitaxial growth of metal thin films on chemically cleaned GaN surfaces, metal silicides for Schottky contacts and metallization schemes for ohmic contacts. We found that many fcc and hcp metals can grow epitaxially on (0001) GaN surfaces at room temperature without in-situ surface cleaning. Metal silicide contacts (such as PtSi) may be more suitable for high temperature applications than elemental contacts, due to the thermal stability of silicides. The intrinsic mechanisms for ohmic behavior for various metal contacts are not well understood at present. More consistent barrier height values measured experimentally can shed light on this issue. Due to the defective nature of the GaN layers, carrier transport across the metal/GaN interface can be due to a number of transport mechanisms, thus making accurate determination of the barrier height difficult. In spite of these difficulties, it seems possible to draw certain general conclusions on the electrical behavior of metal contacts on n-GaN.