Nonradiative centers in deep-UV AlGaN-based quantum wells revealed by two-wavelength excited photoluminescence

• Published in: Physica Status Solidi. B: Basic Solid State Physics Vol. 252; no. 5; pp. 936 - 939
• Main Authors: Kamata, N., Touhidul Islam, A. Z. M., Julkarnain, M., Murakoshi, N., Fukuda, T., Hirayama, H.
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.05.2015
• Subjects: AlGaN; Chemical vapor deposition; Electrodes; Excitation; Mathematical analysis; Mathematical models; nonradiative recombination centers; Photoluminescence; Quantum wells; Sapphire; two-wavelength excitation
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201451582

We have succeeded in detecting nonradiative recombination (NRR) centers in InAlGaN multiple quantum wells (MQWs) for the sterilization wavelength at around 265 nm by our scheme of two‐wavelength excited photoluminescence (PL). Samples studied are InAlGaN multiple quantum well structures with InAlGaN electron blocking layer grown on sapphire (0001) substrates by metal‐organic chemical vapor deposition (MOCVD) technique at the growth temperature of 880 °C (sample A) and 920 °C (sample B). The MQW consists of three InAlGaN wells of 2 nm sandwiched by 7 nm InAlGaN barrier layers. With the addition of the below‐gap excitation (BGE) light of 1.17 eV, the PL intensity decreased for the sample A but increased for the sample B. Both change in the PL intensity implies the existence of NRR centers, which were activated by the BGE. We attribute both intensity change to two‐levels model and one level model, respectively. Based on rate equation analysis, a set of NRR parameters of sample B was determined by utilizing a saturating tendency of the PL intensity change. Spectroscopic and quantitative advantages of the method enable us to clarify energy distribution of NRR centers without providing electrode.