Nonalloyed Al ohmic contacts to MgxZn1-xO

Al nonalloyed ohmic contacts were fabricated and characterized on MgxZn1-xO (0 less than or equal to X less than or equal to 0.34) epilayers, which were grown on R-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). Specific contact resistances were evaluated by the transmission line method (TLM). A specific contact resistance of 2.5 x 10(-5) Omegacm(2) was obtained for Al contact to ZnO with an electron concentration of 1.6 x 10(17) cm(-3). The current flow mechanism was studied by investigating the dependence of specific contact resistances on electron concentration and on temperature. For Al contact to Mg0.34Zn0.66O, specific contact resistance values are two orders of magnitude larger than that of Al ohmic contacts to ZnO.