| Summary: | 碩士 === 國立交通大學 === 光電工程系所 === 94 === In this thesis, we investigate the performance of GaN based micro-cavity light emitting diode (MCLED) with two fabrication techniques for the realization of electrically injected GaN VCSEL. One of the techniques is the use of high-transmittance transparent contact, ITO film. The device shows the turn on voltage is a comparable value with Ni/Au device to be about 3.4V and 530Ω, respectively. The emission peak wavelength of the ITO MCLED was located at 458nm with a narrow line-width of 2nm. Compared to the emission spectrum of the conventional Ni/Au MCLED, the ITO MCLED shows a relatively excellent line-width and possesses a high Q factor of about 229. The improvement of Q factor shows that the non-absorbed transparent contact indeed plays an important role to fabricate this kind of high Q device like VCSEL. Moreover, the “bright spots” within the emission aperture were also discussed. We found the Q factors at the bright spots are relatively higher than those within the dark regions, even as high as 894. The excellent Q factor is the best value compared with that of MCLED published in the recent literatures. The other technique is current confinement using Mg ion implantation. The device is implanted by 80keV Mg with does of 2E15. Moreover, 100nm thick SiNx as buffer layer is required for avoiding damage induced defect in MQWs. The absence of side wall emission of implanted MCLED not only confirms the existence of leakage current in our conventional device but also verifies the current confinement was successful. Such techniques could be the basis for electrically injected GaN-based VCSEL.
|
|---|
