Studies on the effect of ammonia flow rate induced defects in gallium nitride grown by MOCVD
2010 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 21, 3151-3155 p.Article in journal (Refereed) Published
Gallium nitride (GaN) epitaxial layers were grown with different V/III ratios by varying the ammonia (NH3) flow rate, keeping the flow rate of the other precursor, trimethylgallium (TMG), constant, in an MOCVD system. X-ray rocking curve widths of a (1 0 2) reflection increase with an increase in V/III ratio while the (0 0 2) rocking curve widths decrease. The dislocation density was found to increase with an increase in ammonia flow rate, as determined by hot-wet chemical etching and atomic force microscopy. 77K photoluminescence studies show near band emission at 3.49 eV and yellow luminescence peaking at 2.2 eV. The yellow luminescence (YL) intensity decreases with an increase in V/III ratio. Positron annihilation spectroscopy studies show that the concentration of Ga-like vacancies increases with an increase in ammonia flow rate. This study confirms that the yellow luminescence in the GaN arises due to deep levels formed by gallium vacancies decorated with oxygen atoms.
Place, publisher, year, edition, pages
2010. Vol. 312, no 21, 3151-3155 p.
High resolution X-ray diffraction, Point defects, Metal-organic chemical vapor deposition, Semiconducting III-V materials
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:kth:diva-31331DOI: 10.1016/j.jcrysgro.2010.07.063ISI: 000286407100019ScopusID: 2-s2.0-77956884664OAI: oai:DiVA.org:kth-31331DiVA: diva2:404604
QC 201103172011-03-172011-03-142011-03-17Bibliographically approved