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Articles you may be interested inDeep level transient spectroscopy in plasma-assisted molecular beam epitaxy grown Al 0.2 Ga 0.8 N / GaN interface and the rapid thermal annealing effect

The broad photoluminescence band with a maximum at about 2.9 eV widely observed in undoped epitaxial GaN is studied as a function of temperature and excitation intensity. We attribute the band to transitions from a shallow donor to a deep localized acceptor. The zero-phonon transition for this band is at 3.098 eV as determined from the fine structure at low temperatures. A local vibrational mode in the ground state with an energy of 36 meV is found.

Codoping of p-type GaN with Mg and oxygen was investigated. By codoping with oxygen the hole concentrations increased to 2×1018 cm−3 at 295 K, an order of magnitude greater than in Mg-doped epilayers. The resistivity of codoped layers decreased from 8 to 0.2 Ω cm upon oxygen codoping. Variable temperature Hall effect measurements indicated that the acceptor activation energy decreases from 170±5 meV in Mg-doped films to 135±5 meV upon oxygen doping. The higher hole concentration results in part from a decrease in the ionization energy of the acceptor.