Study of Nonradiative Recombination Centers in n-GaN Grown on LT-GaN and AlN Buffer Layer by Below-Gap Excitation
| Autor: | Norihiko Kamata, A. Z. M. Touhidul Islam, Md. Dulal Haque, M. Julkarnain |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Quenching Photoluminescence Materials science General Engineering Analytical chemistry 02 engineering and technology Rate equation 021001 nanoscience & nanotechnology 01 natural sciences Wavelength Excited state 0103 physical sciences Metalorganic vapour phase epitaxy 0210 nano-technology Layer (electronics) Excitation |
| Zdroj: | Advances in Materials Physics and Chemistry. :143-155 |
| ISSN: | 2162-5328 2162-531X |
| DOI: | 10.4236/ampc.2018.83010 |
| Popis: | Nonradiative recombination (NRR) centers in n-type GaN samples grown by MOCVD technique on a LT-GaN buffer layer and aAlN buffer layer have been studied by two wavelength excited photoluminescence (TWEPL). The near band-edge photoluminescence (PL) intensity decreases due to the superposition of below-gap excitation (BGE) light of energies 0.93, 1.17 and 1.27 eV over above-gap excitation (AGE) light of energy 4.66 eV. The decrease in PL intensity due to the addition of the BGE has been explained by a two levels recombination model based on SRH statistics. It indicates the presence of a pair of NRR centers in both samples, which are activated by the BGE. The degree of quenching in PL intensity for the sample grown on LT-GaN buffer layer is stronger than the sample grown on AlN buffer layer for all BGE sources. This result implies that the use of the AlN buffer layer is more effective for reducing the NRR centers in n-GaN layers than the LT-GaN buffer layer. The dependence of PL quenching on the AGE density, the BGE density and temperature has been also investigated. The NRR parameters have been quantitatively determined by solving rate equations and fitting the simulated results with the experimental data. |
| Databáze: | OpenAIRE |
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