Resolution of Discrete Excited States in InGaN Multiple Quantum Wells using Degenerate Four Wave Mixing

• Main Authors: Kundys, D. O, Wells, J. -P. R, Andreev, A. D, Hashemizadeh, S. A, Wang, T, Parbrook, P. J, Fox, A. M, Mowbray, D. J, Skolnick, M. S
• Format: Journal Article
• Language: English
• Published: 14-01-2014
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Optics
• DOI: 10.48550/arxiv.1401.3156

Physical Review B 73, 165309 ?2006? We report on two pulse, degenerate four wave mixing (DFWM) measurements on
shallow InGaN/GaN multi-quantum wells (MQWs) grown on sapphire substrates.
These reveal pulse length limited signal decays. We have found a 10:1 resonant
enhancement of the DFWM signal at the excitonic transition frequencies which
thereby give a sharp discrimination of the discrete excitonic contributions
within the featureless distribution seen in absorption spectra. The exciton
resonances have peak positions, which yield good overall agreement with a full
k.P model calculation for the quantum well energy levels and optical transition
matrix elements. InGaN/GaN MQWs generally exhibit strongly inhomogeneously
broadened excitation spectra due to indium fluctuation effects; this approach
therefore affords a practical method to extract information on the excited
excitonic states not available previously