Gallium nitride heterostructures sandwiched between AlGaN layers were grown on sapphire substrates using rf-plasma-assisted molecular-beam epitaxy and their electrical properties were investigated. Deep-level transient spectroscopy measurements revealed that the activation energies of the 2 electron levels were 0.21 and 0.23eV relative to the conduction band, with capture cross-sections of 5.0 x 10-15 and 7.4 x 10-17cm2, respectively. From the capture kinetics of the deep-level defects, according to the filling pulse duration and the bias voltage, it was suggested that the 0.21eV defect was associated with N vacancies and the 0.23eV defect was associated with extended defects.

Deep-Level Defects in AlGaN/GaN Heterostructures Grown Using rf-Plasma-Assisted Molecular Beam Epitaxy. C.J.Park, Y.S.Park, H.S.Lee, I.T.Yoon, T.W.Kang, H.Y.Cho, J.E.Oh, K.L.Wang: Japanese Journal of Applied Physics, 2005, 44[4A], 1722-5