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

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 x 10(16)/cm(3), the contact resistivity decreased from 2.9 x 10(-1) to 7.1 x 10(-3) Ohm 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. (C) 1998 Elsevier Science Ltd. All rights reserved.