| Summary: | 碩士 === 北台灣科學技術學院 === 機電整合研究所 === 96 === In this work, we study the transferring mechanisms of excitons in InGaN/GaN multiple-quantum-well (MQW) heterostructures. Electro- luminescence (EL) measurements for the structures were prosecuted over a broad range of temperature and injection current. The measured temperature dependent EL peak energy and EL linewidth are demonstrated to be in fair agreement with the process of hopping and thermalization of the localized excitons within indium-rich regions in the quantum wells.
The sample used in the research was grown by metal-organic chemical vapor deposition system. Five pairs of InGaN/GaN multiple-quantum-well (MQW) were used as the active region of the structure. From the measured temperature-dependent EL spectra, a trend of ‘S-shaped’ behavior (redshift-blueshift-redshift) of the emission peaks, and a nonmonotonous behavior of the full-width at half-maximum (FWHM), were observed with increasing temperatures. The exciton-localization effect and the heating effect on InGaN/GaN heterostructures are discussed in detail to investigate the carriers transferring mechanisms. Moreover, the variations of EL external quantum efficiency as a function of injection current at various temperatures are also obtained. It is observed that the temperature behavior of the EL efficiency is strongly dependent on the injection current. The discussion exhibits a good agreement with our experimental results.
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