| Summary: | 碩士 === 國立高雄大學 === 應用物理學系碩士班 === 103 === First, we have shown the experimental results of scanning electron microscope (SEM), cathodoluminescence (CL), atomic force microscopy (AFM), X-ray diffraction (XRD), photoluminescence (PL), electroluminescence (EL), current-voltage (I-V), and time-resolved electroluminescence (TREL) measurements of the polar c-plane and nonpolar m-plane InGaN/GaN MQW samples and LEDs. The larger surface roughness and weaker CL intensity of the nonpolar m-plane InGaN/GaN MQW sample than those of the polar c-plane one show a higher defect density and lower sample quality of the nonpolar m-plane one. The result of CL measurement is consistent of that of the AFM measurement. In addition, the DoP of PL of the nonpolar m-plane InGaN/GaN MQW sample is larger than the polar c-plane one. With increasing temperature from 20 to 300 K, PL position of the polar c-plane InGaN/GaN MQW sample is slightly blue-shifted, while that of the nonpolar m-plane one is red-shifted. The shorter response time of the nonpolar m-plane InGaN/GaN MQW LED than that of the polar c-plane one suggest a better injection efficiency. The longer recombination time of the polar c-plane InGaN/GaN MQW LED than that of the nonpolar m-plane one could be due to the larger QCSE and potential distribution in the MQWs.
Second, we have shown the experimental results of SEM, CL, XRD, AFM, PL measurements and annealing affect of the N-Polar InGaN/GaN MQW samples. The surface roughness of the N-polar t11@t22 sample is larger than that of the N-polar t11@t25 one. The N-polar InGaN/GaN MQW and t11@t22 InGaN/GaN MQW samples show a larger area ratio of InGaN mounds. The indium content of the N-polar t11@t22 InGaN/GaN MQW sample is larger than those of the N-polar t11@t25 one. With increasing temperature from 20 to 300 K, the integral PL intensity of the N-polar InGaN/GaN MQW sample decays faster than those of the N-polar one. The surface roughness of the two annealed samples becomes smoother. With thermal annealing, the relative intensities of UV and visible peaks in the CL spectra are changed and the InGaN intensity increases in XRD measurement. The mound and light densities of the annealed N-polar samples are larger than those of the as-grown ones.
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