| Summary: | 碩士 === 國立中央大學 === 光電科學與工程學系 === 106 === In recent years, III-nitride compounds exhibit excellent properties in wide applications of light-emitting diodes, displays, backlight modules, medical components, etc. Understanding the crystal properties of InGaN quantum wells is the key step to further improve the performances of nitride-based emitters.
In this research, we studied nanostructured semipolar {10-11} InGaN/GaN multiple quantum wells (MQW) using temperature-dependent, power-dependent and time-resolve photoluminescence (PL) spectra. The semipolar MQW were grown on (100) Si substrates by metal-organic chemical vapor deposition(MOCVD). To relieve the huge lattice strain between Si and GaN and to attain the semipolar crystal plane, ZnO nanorods were employed as the buffer layer.
From the results of temperature and power-dependent PL studies, the semipolar MQW display clear S-shape spectra and varied quantum-confined Stark effect (QCSE), indicating a quantum-dot-like structure due to indium segregation. The internal quantum efficiency is estimated to be 66%. From time-resolve PL, the carrier lifetime in the semipolar MQW is around 0.5 ns, much shorter than that (3.7 ns) of the conventional planar polar MQW. The result is attributed to the alleviated strain brought by the ZnO nanorods, as well as the mitigated QCSE.
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