Mechanism of nonalloyed Al ohmic contacts to n-type ZnO:Al epitaxial layer

The mechanism of Al ohmic contacts to n-type zinc oxide (ZnO:Al) epitaxial layer was investigated. The formation of an Al-ZnO interfacial phase at room temperature was responsible for the low specific resistivity (8 +/- 0.3 x 10(-4) Omegacm(2)). The results of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) depth profiles, and glancing angle X-ray diffraction (GXRD) indicate that an interfacial reaction between Al and ZnO results in an increased doping concentration in the region of the ZnO surface resulting in a low specific contact resistivity without the need for a thermal annealing process.