The mechanism of current flow in an alloyed In-GaN ohmic contact

The resistance of alloyed In-GaN ohmic contact is studied experimentally. In the temperature range 180-320 K, the resistance per unit area increases with temperature, which is typical of metallic conduction and disagrees with current flow mechanisms associated with thermionic, field-effect, or thermal field emission. It is assumed that In-GaN ohmic contact is formed by conducting shunts arising due to precipitation of In atoms on dislocations. As determined from the temperature dependence of the contact resistance, the number of shunts per unit contact area is similar to(10(7)-10(8)) cm(-2), which is close to the dislocation density of 10(8) cm(-2) measured in the initial material.