Pinning-controlled ohmic contacts: application to SiC(0001)

Abstract

We propose a new systematic method to make ohmic contacts by reducing Schottky barrier heights by decreasing the density of interface electronic states. The decrease in the density of states releases the Fermi level of the interface from pinning. This results in the barrier height being determined simply by the difference between the work function of the metal and the electron affinity of the semiconductor. An atomically flat surface is a prerequisite for the decrease in the density of interface states. We apply an established hydrogen termination technique to passivate a semiconductor surface using a chemical solution, pH controlled buffered HF or boiling water. We have demonstrated this type of ohmic contacts without a Schottky barrier on silicon carbide (0001) surfaces without post-annealing.