Detection and identification of donors in hydride-vapor-phase epitaxial GaN layers

Low temperature photoluminescence experiments carried out on HVPE GaN samples produced in two different reactors are consistent with a low background level of donors and an extremely low concentration of compensating shallow acceptors. Infrared absorption experiments on these samples indicated that different shallow donors are incorporated at different rates in each reactor. High sensitivity SIMS was employed to measure the concentration of background impurities of a number of samples produced in both reactors. The comparison between the infrared absorption cross-sections with the SIMS results allows the identification of Si, the shallower, and O as the two dominant residual donors in these examples of HVPE GaN.