Effect of surface treatment by KOH solution on ohmic contact formation of p-type GaN

Abstract

The lowest contact resistivity was achieved by the surface treatment of p-type GaN using KOH solution prior to Pd/Au metal deposition. For the p-type GaN with a hole concentration of 2.9×10 16/cm 3, the contact resistivity decreased from 2.9×10 −1 to 7.1×10 −3 Ω cm 2 by the surface treatment. This is the lowest value among the previous results ever reported on the formation of ohmic contacts to p-type GaN. The surface treatment is effective in removing the surface oxides formed on p-type GaN during the epitaxial growth which play a role to inhibit the hole transport from metal to p-type GaN.