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Detection of dislocation‐related midgap levels in pulsed laser deposited GaN by photo‐induced current transient spectroscopy
Author(s) -
Kumar M. Senthil,
Srivatsa K. M. K.,
Kushvaha S. S.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451454
Subject(s) - materials science , sapphire , dislocation , epitaxy , acceptor , deep level transient spectroscopy , optoelectronics , activation energy , crystallite , band gap , spectroscopy , analytical chemistry (journal) , laser , layer (electronics) , condensed matter physics , silicon , chemistry , optics , nanotechnology , physics , organic chemistry , quantum mechanics , chromatography , metallurgy , composite material
Deep levels in unintentionally doped GaN epilayers grown on sapphire (0001) by ultra high vacuum pulsed laser deposition at 600 and 700 °C have been studied using photo‐induced current transient spectroscopy (PICTS). The GaN epitaxial layers were deposited by laser ablating a hydride vapor phase epitaxy grown bulk GaN polycrystalline target in the ambient of r.f. nitrogen radicals. The activation energy of dark conductivity for these layers lies in the range 0.17–0.25 eV. An acceptor‐like deep trap level is detected in the PICTS spectrum with activation energy of 1.32 eV. For the 700 °C grown GaN layer, an additional well‐pronounced acceptor‐like defect level near mid‐gap at 1.52 eV has been observed. From the analysis of trap capture kinetics, both defect levels are identified to be extended ‘bandlike’ electronic states associated with extended defects such as dislocations present in GaN layers.