Mechanism of carrier injection in (Ni/Au)/p-AlxGa1-xN:Mg(0≤x<0.1) Ohmic contacts

Nikishin, S.; Chary, I.; Borisov, B.; Kuryatkov, V.; Kudryavtsev, Yu.; Asomoza, R.; Karpov, S. Yu.; Holtz, M.
October 2009
Applied Physics Letters;10/19/2009, Vol. 95 Issue 16, p163502
Academic Journal
We report the mechanism of current injection in (Ni/Au)/p-AlxGa1-xN:Mg(0≤x<0.1) Ohmic contacts based on the temperature dependence of hole concentrations (p) and specific contact resistance (ρc). The injection mechanism is found to be thermionic emission in all cases. A model is developed to describe the temperature dependences of p and ρc for Mg concentrations from 1019 to 1020 cm-3. The model takes into account splitting in the valence band structure, hole activation energy, and Schottky barrier height. For GaN (AlGaN) these are found to be 132–140 (135–150) meV and 66–88 (84–93) meV, respectively.


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