Deep electron and hole traps in neutron transmutation doped n-GaN

In neutron transmutation doped n-GaN, the electrical properties are found to be dominated not by shallow Ge donors produced by interaction of thermal neutrons with Ga, but by electron traps at 0.45 or 0.2 eV. The traps switch from the former to the latter when the anneal temperature increased from 800 to 1000 degrees C. The concentrations of both traps rose linearly with neutron fluence and were close to the concentration of Ge donors, suggesting they are Ge complexed with different radiation defects. The authors note the similarity of the properties of these traps to the properties of the dominant electron traps in as-irradiated n-GaN. They also observed prominent hole traps with a level near E-v+1.2 eV. These traps were not detected in virgin or as-irradiated samples. The concentration of the 1.2 eV hole traps increased linearly with neutron fluence, and these traps were assigned to Ga vacancy complexes with oxygen. (C) 2011 American Vacuum Society. [DOI: 10.1116/1.3596571]