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Quantum-well-width dependencies of postgrowth thermal annealing effects of InGaN/GaN quantum wells

2003; American Institute of Physics; Volume: 93; Issue: 12 Linguagem: Inglês

10.1063/1.1576514

1520-8850

Yi-Yin Chung, Yen-Sheng Lin, Shih‐Wei Feng, Yung‐Chen Cheng, En‐Chiang Lin, C. C. Yang, Kung‐Jen Ma, Cheng Hsu, Hui‐Wen Chuang, Cheng‐Ta Kuo, J. S. Tsang,

ZnO doping and properties

Optical measurements of temperature-dependent photoluminescence (PL) spectral peak, integrated PL intensity and PL decay time, and microstructure analyses with high-resolution transmission electron microscopy showed the strong dependencies of thermal annealing effects on quantum well (QW) width in InGaN/GaN QW structures. With different QW widths, different levels of strain energy were built. Upon thermal annealing, energy relaxation resulted in the reshaping of quantum dots and hence the changes of optical properties. Thermal annealing at 800 °C of a narrow QW width (2 nm) structure led to regularly distributed quantum dots (QDs) and improved optical quality. However, thermal annealing at the same temperature of a sample of larger QW width (4 nm) did not show QD formation. In this situation, even higher local strains around QWs were speculated. Also, degraded optical quality was observed.