| Summary: | 碩士 === 長庚大學 === 電子工程學系 === 104 === In this dissertation, we use GaN/AlGaN multiple quantum well (MQW) structure by reducing MQW well(GaN) thickness, the emission peak will blue shifted by quantum confinement. We can use this method to let GaN emission peak less than 365nm. We use atmospheric pressure MOCVD to grow three MQW structure samples. We design three samples have the different well(GaN) thickness, and have the same barrier(Al0.113Ga0.887N) thickness. In XRD measurement, we can calculate the MQW structure well and barrier thickness and the barrier(AlGaN) Al content. By room temperature PL measurement, we know the Sample A(0.87nm) well thickness is 0.87nm have the main emission peak at 348nm. We know the Sample B(1.75nm) have the most small FWHM, due to the nanostructure less appear the impurities. In 20K to 300K temperature PL measurement, we know the active energy and internal quantum efficiency become smaller by increasing the well thickness. The MQW well become thinning, the temperature don’t easily effect the emission peak because temperature insensitive. The MQW well thinning, less phonon and exciton scattering which mean the FWHM can keep the FWHM quality with temperature growth. From the results of analysis, we know when the wavelength not too short from GaN(365nm), such as the Sample B(1.75nm) the emission peak is 356nm, we can use quantum confinement effect to achieve. Also has a better film quality, and the temperature don’t easily effect the emission wavelength and FWHM.
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