Abstract

A guideline for development of low-resistance Ohmic contact materials is to form Intermediate Semiconductor Layers (ISLs) with high dopant concentration or low energy barrier (φ_B) at the metal/ semiconductor interface by metallurgical reactions. For n-GaAs, Ge in AuNiGe and In in NiInW are found to play an important role in forming these ISLs. For p-GaN. In is a candidate element to form ISL with low φB p-type ISL, but a method to form ISL metallurgically has not been discovered yet. On the other hand, as a specific phenomenon, thermal annealing in oxygen ambient and metal/InSnO contact has been found to be effective in reducing the contact resistivity. Oxygen plays an essential role in the metallurgical reaction, but its materials science guideline remains unresolved to this day.

Keywords:Ohmic contact materials; p-GaN; Metallurgy; Metal/semiconductor interface; Oxygen annealing; Intermediate semiconductor layer