Contactless electroreflectance of InGaN layers with indium content <=36%: The surface band bending, band gap bowing, and Stokes shift issues
- Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw (Poland)
- Institute of High Pressure Physics, Polish Academy of Science, Sokolowska 29/37, 01-142 Warsaw (Poland)
Contactless electroreflectance (CER) supported by photoluminescence (PL) has been applied to study (i) the surface band bending, (ii) the band gap bowing, and (iii) the Stokes shift for InGaN layers grown by molecular beam epitaxy with 0.14<=In<=0.36. The type of surface band bending has been investigated on the basis of the shape of CER resonance. It has been found that the surface band bending changes from n-type for layers with low indium content (In<27%) to flatband (or weak p-type band) for layers with Inapprox35%. The band gap bowing has been determined to be 1.4+-0.2 and 2.1+-0.3 eV for CER data with and without strain corrections, respectively. From this analysis it has been concluded that the reliable value of the bowing parameter for unstrained InGaN should be between 1.4 and 2.1 eV. Comparing CER with PL data it has been found that the Stokes shift rises from 20 to 120 meV when the indium concentration increased from 14% to 36%. In addition, it has been observed that the intensity of PL from InGaN layers decreased exponentially with the increase in the indium content. The last two findings are attributed to an easier formation of native point defects and stronger indium segregation in InGaN alloys with higher indium concentrations.
- OSTI ID:
- 21359375
- Journal Information:
- Journal of Applied Physics, Vol. 106, Issue 11; Other Information: DOI: 10.1063/1.3266011; (c) 2009 American Institute of Physics; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BENDING
BOWING
CRYSTAL GROWTH
ENERGY GAP
EV RANGE 01-10
GALLIUM ALLOYS
GALLIUM NITRIDES
INDIUM
INDIUM ALLOYS
INDIUM NITRIDES
LAYERS
MOLECULAR BEAM EPITAXY
PHOTOLUMINESCENCE
POINT DEFECTS
SEGREGATION
SEMICONDUCTOR MATERIALS
THIN FILMS
ALLOYS
CRYSTAL DEFECTS
CRYSTAL GROWTH METHODS
CRYSTAL STRUCTURE
DEFORMATION
ELEMENTS
EMISSION
ENERGY RANGE
EPITAXY
EV RANGE
FILMS
GALLIUM COMPOUNDS
INDIUM COMPOUNDS
LUMINESCENCE
MATERIALS
METALS
NITRIDES
NITROGEN COMPOUNDS
PHOTON EMISSION
PNICTIDES