Characterization of the Shallow and Deep Levels in Si Doped GaN Grown by Metal-Organic Vapor Phase Epitaxy

Abstract

Si doped GaN with room temperature free carrier concentration 1.1× 10¹⁷ cm^-3 studied using the Hall effect exhibits exponential carrier freeze-out over a large range with activation energy 28.0± 0.5 meV; however, resistivity dependence on temperature suggests carrier hopping occurs at low temperature. GaN with greater Si concentration displays metallic impurity band conduction following the two-band model. Deep level transient spectroscopy results show a negligible concentration of other deep donors from native defects or unintentionally included impurities indicating that the active shallow donor is uniquely Si; however, photoluminescence tests show broad yellow emission with peak energy ∼ 2.2 eV commonly observed in Si doped GaN.