| Summary: | 博士 === 國立臺灣大學 === 電機工程學研究所 === 92 === In this dissertation, we report the plasma-assisted gas-source molecular-beam epitaxial growth of cubic GaN film and InGaAsN quantum-well (QW) lasers. We firstly present the study on the growth and characterization of cubic GaN films on GaAs substrate. It was found that the V/III ratio during the epitaxial growth must be kept at the lowest possible level that still can prevent the formation of Ga droplet on the surface. The condition can enhance the surface migration of Ga atoms and thus greatly improve the optical quality. After further optimizing the growth temperature and the buffer-layer growth procedures, we obtained cubic GaN films with high cubic-phase purity and high optical quality.
The study of InGaAsN/GaAs QW lasers is then presented. After the optimization on the growth conditions and layer structures, 1300nm InGaAsN QW lasers grown on GaAs substrate are demonstrated. The infinite cavity threshold current density is 1460 A/cm2. Internal quantum efficiency is 72% and internal loss is 6.8 cm-1. We also demonstrate a highly-strained InGaAs/GaAs QW laser with an emission wavelength of 1244 nm. To our best knowledge, it is the longest wavelength ever reported for strained InGaAs/GaAs edge-emitting lasers.
The temperature behavior of an InGaAs/GaAs QW laser was characterized and analyzed. The carrier distribution in the active region of the laser was calculated at various temperatures and used to simulate the gain, spontaneous emission, and current components of the device. Coefficients of Shockley-Reed-Hall, radiative and Auger recombination rates and their temperature relations were extracted. Finally, the characteristic temperatures of laser devices with different cavity lengths were calculated and compared with the experimental results. Good agreement is demonstrated.
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