| Summary: | 博士 === 國立交通大學 === 電子工程系 === 89 === In this dissertation, we have successfully fabricated AlGaAs and Al-free Vertical Cavity Surface Emitting Lasers (VCSELs) by MOVPE system. Firstly, we discuss the design rule for the VCSEL, the main effort is put on how to achieve high reflectivity and low resistance distributed Bragg reflectors. (DBRs)
Secondary, we have do many experiment to achieve the good quality of the active region of the VCSELs, and find the best condition to growth InGaAs quantum wells. We also succeed in epi high quality AlGaAs VCSEL epi wafer, and investigate the quick process of VCSEL to qualify the quality of epi wafer. By the way, we also developed the low leakage current process of VCSELs, and make a low threshold CW operation VCSEL devices.
On the Al-free topics, that is to say GaAs and GaInP materials. The reason why the intermediate layer existed between the GaAs and GaInP is still under debate. We successfully made the world’s most narrow FWHM of PL spectrum (6.7 meV) by adding 1 nm lattice matched GaAsP between GaAs and GaInP to. We also built a In memory effect model to account the result. In the mean time, we have achieve the Al-free VCSEL by MOVPE. But we found, add 1nm GaAsP will drastically increased the resistance of the VCSEL devices. Because the In memory effect strongly related with the hardware of MOVPE system, especially the gas switches system. So we think to improve the hardware of MOVPE system maybe the direct way to improve the optical and electrical quality of Al-free materials
Finally, we put some effort on single transverse mode VCSEL on 850 nm products. There are two methods to investigate the single mode VCSELs. One is use the small oxidation aperture, the other is use the surface relief technique. We use the Germanium as the anti-reflection coating material to spatially control the threshold of VCSELs. And we have made single transverse mode VCSEL and exhibit stable single lobe in near field measurement. So it is very suitable for the next generation’s communication devices.
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