Author(s)

M. D. Haque^1,2, M. Julkarnain³, A. Z. M. Touhidul Islam⁴, N. Kamata¹

¹Department of Functional Materials Science, Saitama University, Saitama, Japan.
²Department of Electronics and Communication Engineering, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh.
³Department of Applied Physics and Electronic Engineering, University of Rajshahi, Rajshahi, Bangladesh.
⁴Department of Electrical and Electronic Engineering, University of Rajshahi, Rajshahi, Bangladesh.

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.

N-Type GaN, Two-Wavelength Excited Photoluminescence, Nonradiative Recombination Center, Recombination Model

Haque, M. , Julkarnain, M. , Islam, A. and Kamata, N. (2018) Study of Nonradiative Recombination Centers in n-GaN Grown on LT-GaN and AlN Buffer Layer by Below-Gap Excitation. Advances in Materials Physics and Chemistry, 8, 143-155. doi: 10.4236/ampc.2018.83010.