Carrier transport mechanism at metal/amorphous gallium indium zinc oxides interfaces

Abstract

We report the carrier transport mechanism of Ni/Au Ohmic contacts to amorphous gallium indium zinc oxides. Despite the expected large barrier height, Ohmic contact could be achieved due to the trap-assisted tunneling associated with localized tail states. Upon thermal annealing, the specific contact resistance was further reduced to 3.28 × 10 -4 Ωcm 2, accompanied by a change in the predominant transport mechanism from trap-limited conduction to degenerate conduction. The Ohmic mechanism could be explained in terms of the thermionic field emission model, yielding a tunneling parameter of 49 meV, a Schottky barrier height of 0.63 eV, and a barrier width of 5.2 nm. © 2012 American Institute of Physics.