Article

Filtering of Defects in Semipolar (11-22) GaN Using 2-Steps Lateral Epitaxial Overgrowth

Centre de Recherche sur l'Hétéroépitaxie et ses Applications CRHEA-CNRS, Rue Bernard Grégory, Sophia Antipolis, 06560 Valbonne, France.
Nanoscale Research Letters (Impact Factor: 2.48). 12/2010; 5(12):1878-1881. DOI: 10.1007/s11671-010-9724-9
Source: PubMed

ABSTRACT Good-quality (11-22) semipolar GaN sample was obtained using epitaxial lateral overgrowth. The growth conditions were chosen to enhance the growth rate along the [0001] inclined direction. Thus, the coalescence boundaries stop the propagation of basal stacking faults. The faults filtering and the improvement of the crystalline quality were attested by transmission electron microscopy and low temperature photoluminescence. The temperature dependence of the luminescence polarization under normal incidence was also studied.

Download full-text

Full-text

Available from: Philippe Vennéguès, Feb 13, 2014
0 Followers
 · 
133 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the optical and the crystal qualities of epitaxial lateral overgrown (ELO) semipolar (11-22) GaN produced using three growth steps: growth of the seed layer for the [11-20] a-direction, the formation of a semipolar (11-22) plane, and the lateral coalescence step with a [11-22] direction. Fully-coalesced ELO-GaN had a good surface morphology and a very low defect density of similar to 5.5 x 10(5) cm(-2), which was smaller than that of conventional c-plane ELO-GaN. In spite of the generation of some crystallographic tilts, the crystal properties were significantly enhanced as a result of the ELO process. The cathodeluminescence intensity of band edge emission in the low defect region was about 3.1 times higher than in the highly defective region, indicating that the optical properties of semipolar GaN could be significantly enhanced by reducing defects.
    Journal of The Electrochemical Society 01/2011; 158(10):H994. DOI:10.1149/1.3617468 · 2.86 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: (1120) non-polar and (1122) semi-polar GaNs with a low defect density have been achieved by means of an overgrowth on nanorod templates, where a quick coalescence with a thickness even below 1 μm occurs. On-axis and off-axis X-ray rocking curve measurements have shown a massive reduction in the linewidth for our overgrown GaN in comparison with standard GaN films grown on sapphire substrates. Transmission electron microscope observation demonstrates that the overgrowth on the nanorod templates takes advantage of an omni-directional growth around the sidewalls of the nanostructures. The dislocations redirect in basal planes during the overgrowth, leading to their annihilation and termination at voids formed due to a large lateral growth rate. In the non-polar GaN, the priority 〈0001〉 lateral growth from vertical sidewalls of nanorods allows basal plane stacking faults (BSFs) to be blocked in the nanorod gaps; while for semi-polar GaN, the propagation of BSFs starts to be impeded when the growth front is changed to be along inclined 〈0001〉 direction above the nanorods.
    Applied Physics Letters 03/2013; 102(10). DOI:10.1063/1.4795619 · 3.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper reports on the improved properties of semipolar (11–22) GaN with embedded InN islands on m-plane sapphire substrate. The crystal quality of GaN grown over embedded InN islands was improved by the defect blocking mechanism that the InN islands stop from propagating of dislocations. The full width at half maximum (FWHM) of X-ray rocking curves for the on- and off-axes planes of GaN with embedded InN islands significantly narrowed. The photoluminescence (PL) intensity of GaN with embedded InN islands increased by 28% compared with that of GaN without InN islands (reference GaN). The n-type GaN carrier mobility was analyzed by using temperature-dependent Hall effect measurement. The increase in peak mobility at 350 K from 104 to 113 cm2/Vs with embedded islands also suggested the effectiveness of embedded InN islands in GaN. LEDs fabricated on (11–22) GaN with embedded InN islands showed approximately 2.7 times higher optical output power than the reference LED at 100 mA.
    Journal of Crystal Growth 05/2013; 370:26–29. DOI:10.1016/j.jcrysgro.2012.09.022 · 1.69 Impact Factor