Influence of oxygen on the activation of p-type GaN

The presence of oxygen in the annealing environment can exhibit a strong influence on the activation of p-GaN, as demonstrated by experiments described in this letter. We activated p-GaN at 600-900 degrees C in four environments: ultrahigh purity (UHP) N-2 gettered to remove residual O-2, UHP N-2 without gettering, 99.5% UHP N-2/0.5% UHP O-2, and 90% UHP N-2/10% UHP O-2. The resistivity of the p-GaN was lowest when O-2 was intentionally introduced during activation and was highest when extra care was taken to getter residual O-2 from the annealing gas. The experiments also demonstrate that unintentionally incorporated O-2 can be at high enough levels to influence the activation process. (C) 2000 American Institute of Physics. [S0003-6951(00)03316-7].