p-Ohmic contact resistance for GaAs(C)/GaN(Mg)

Heavily carbon-doped (p greater than or equal to 10(10) cm(-3)) GaAs layers were grown on p-GaN in attempt to reduce the p-ohmic contact resistance. While the specific contact resistances on the p-GaN and p-GaAs were typical of the current state-of-the-art (similar to 10(-3) and 10(-5) Omega cm(3), respectively), the high valence band offset at the GaAs/GaN interface produced a barrier to hole transport. The specific contact resistance for the GaAs(C)/GaN(Mg) structure was better than that of GaN alone, but was still in the 10(-3) Omega cm(2) range, even after alloying of the metal at 800 degrees C. Other approaches to lowering contact resistance on p-GaN are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.