| Summary: | 碩士 === 國立交通大學 === 顯示科技研究所 === 101 === We have successfully grown three thicknesses of single quantum wells (SQWs) by pulsed laser deposition (PLD), which are 2nm, 4nm, and 5.2nm,respectively. Using temperature and pumping power dependent photoluminescence (PL) spectroscopy, we analyze these SQW samples and discuss the properties of (1) phonon interaction, (2) exciton binding energy, and (3) built-in electric field on these samples. From the low-temperature PL spectra of the SQWs have blue shifted D0X emission for 2 nm with the exciton binding energy large than 60meV, whereas, the exciton binding energies for 4nm and 5.2nm SQWs are 54 and 48 meV, respectively, which are less than 60 meV of the bulk ZnO and the phonon interaction decreases with decreasing well width. These results reveal the SQWs possess not only quantum confinement effect but also quantum confined Stark effect with built-in electric field. Furthermore, there is an apparent extra spectral peak in the PL spectrum of the 5.2nm SQW at 3.34eV about 45 meV below the exciton emission. In order to explore the origin of this peak, we made excitation density dependent PL measured at 80K. The results reveal that this extra peak shifts from 45 meV below the exciton emission to about 30 meV at high excitation density. We therefore attribute this peak to the exciton-exciton scattering or so-called the P-band emission that shows changing from P(infinity) emission (45 meV below exciton emission) at low excitation to P2 emission about 30 meV below exciton emission at high excitation density.
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