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Title: Study of carrier recombination transient characteristics in MOCVD grown GaN dependent on layer thickness

The MOCVD grown GaN epi-layers of different thickness have been examined in order to clarify a role of surface recombination, to separate an impact of radiative and non-radiative recombination and disorder factors. The microwave probed –photoconductivity (MW-PC) and spectrally resolved photo-luminescence (PL) transients were simultaneously recorded under ultraviolet (UV) light 354 nm pulsed 500 ps excitation. The MW-PC transients exhibited the carrier decay components associated with carrier decay within micro-crystals and the disordered structure on the periphery areas surrounding crystalline columns. Three PL bands were resolved within PL spectrum, namely, the exciton ascribed UV-PL band edge for hν>3.3 eV, blue B-PL band for 2.5 < hν < 3.0 eV and yellow Y-PL band with hν < 2.4 eV. It has been obtained that intensity of UV-PL band increases with excitation density, while intensity of B-PL band is nearly invariant. However, intensity of the Y-PL increases with reduction of the excitation density. The Y-PL can be associated with trapping centers. A reduction of UV excitation density leads to a decrease of the relative amplitude of the asymptotic component within the MW-PC transients and to an increase of the amplitude as well as duration of the yellow spectral band (Y-PL) asymptotic component.more » Fractional index α with values 0.5 < α < 0.8 was evaluated for the stretched-exponent component which fits the experimental transients determined by the disordered structure ascribed to the periphery areas surrounding the crystalline columns.« less
Authors:
; ; ; ; ; ; ; ;  [1]
  1. Institute of Applied Research, Vilnius University, Sauletekio Ave. 9-III, LT-10222, Vilnius (Lithuania)
Publication Date:
OSTI Identifier:
22251831
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 3; Journal Issue: 11; Other Information: (c) 2013 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHEMICAL VAPOR DEPOSITION; CRYSTALS; DENSITY; EXCITATION; GALLIUM NITRIDES; LAYERS; LUMINESCENCE; SPECTRA; THICKNESS; TRANSIENTS