Muonium in gallium nitride
In this thesis measurements in wurtzite Gallium Nitride are made using muonium, M|i,=|i"^e. Muonium is created by implanting a positive muon into a host sample where it behaves as a light hydrogen-like isotope. Specifically, quadrupole level-crossing resonance (QLCR), transverse field (TF) and zero field (ZF) spin depolarization functions are used to examine Silicon doped and nominally undoped GaN samples. In these samples we have identified two distinct M|Li" sites, the c-axis and off c-axis anti-bonding (AB) Gallium sites. At low temperature the QLCR and ZF data indicate only one of these sites is occupied below 150K with a charge and site transition involving a second charge state occurring between 150K and 200K which results in the occupation of the second site. In addition to these transitions there are also transitions above 600K. At the higher temperatures the depolarization functions indicate a thermally activated hopping motion involving M|i" and having an energy barrier near lev. The polarization dependencies and features indicate the presence of additional M|Lt sites with transitions present among them as well.