THE EFFECT OF ORGANOMETALLIC VAPOR-PHASE EPITAXIAL-GROWTH CONDITIONS ON WURTZITE GAN ELECTRON-TRANSPORT PROPERTIES

The growth issues known to effect the quality of GaN organometallic va por phase epitaxial films are reviewed and the best 300K mobility vs e lectron concentration data are discussed. The data probably represent transport properties intrinsic to films grown on sapphire. From the re sults of Hall measurements, the unintentional donor in high quality Ga N films cannot be Si since the donor ionization energy is much larger than that of films intentionally doped with Si (36 vs 26 meV). Electri cal properties of a doped channel layer are shown not to be significan tly different from those of thick films which implies a viable technol ogy for conducting channel devices. It is argued that 77K Hall measure ments are a useful indicator of GaN film quality and a compilation of unintentionally and Si doped data is presented. The 77K data imply tha t, at least over a limited range, Si-doping does not appreciably chang e the compensation of the GaN. The 77K data indicate that the low mobi lities of films grown at low temperatures are probably not related to dopant impurities.