Resistivity distribution of Au-Ti-Pd ohmic contacts to n-InN

Development of ohmic contacts to InN films is promising for a future technology of gigahertz electronics and modern high-electron-mobility transistors. From the other side, high precision measurement of ohmic contact resistivity is a main demand for a quality and reliability control. However, InN has high density of structural defects, due to growing on the GaN-Al₂O₃ surface. The Transmission Line Method (TLM) was used for measurement of ohmic contact resistivity. Basic statistical analysis of ohmic contact resistivity distribution was made before and after rapid thermal annealing. Optimal annealing conditions of Au-Ti-Pd-InN contacts are defined as 370° C during 2 min. Annealing lead to essential reduction of the ohmic contact resistivity from 1.3-1.6 · 10^-4 Ohm-cm² to 2.4 · 10^-5 Ohm-cm².