Studies Of 1.3 μm VCSEL Structure Fabrication

Vertical cavity surface emitting lasers (VCSELs), with super advantages such as wafer level testing, high coupling efficiency to the optical fiber, high modulation capability and low consumption and so on, are the most promising and competitive light sources in the optical networks. Especially, in recent years, the long-wavelength (1.3～1.55μm) VCSEL for optical communication which is the most suitable light source in the short and intermediate single mode optical networks, develops quickly, and has been investigated widely. This thesis focuses on 1.3μm bonding structural VCSEL. The growth by gas source molecular beam epitaxy (GSMBE) and characterization of VCSEL cell structure materials have been researched in detail, and the low temperature Au-In-Au metallic bonding technique applied to the fabrication of VCSEL has also been studied, which is first in this research field in China. Finally, the VCSEL device fabrication processes have been discussed. Following is the details:According to Thermo V90 GSMBE system, the GSMBE growth parameters of VCSEL materials have been studied. The materials of InAsP/InGaAsP strain-compensated multiple quantum well (SCMQW) active region and GaAs/AlAs distributed Bragg reflectors (DBRs) which used in 1.3μm bonding structure VCSEL were optimized separately grown. And all of them were investigated by using high resolution X-ray diffraction (XRD), fourier transform Infrared (FTIR) spectra, electrochemistry C-V, Hall, and so on. As demonstrated, the interval growth method was developed to improve the crystal quality, and the more pairs the DBR had, the bigger the fluctuation of period thickness would be. The active region and DBR both achieved the designed requirements of bonding structural 1.3μm VCSEL materials.The low temperature Au-In-Au metallic bonding technique was innovatively applied to the VCSEL structure fabrication firstly in China. InP based half-VCSEL structural smples were successfully metallic bonded to the Si substrates at 200℃for 20 minutes using 2MPa pressure in N₂ atmosphere with high bonding strength, smooth interface and no degradation. It not only realized up-down assembled and improved the thermal characteristic of the bonded devices, but also enhanced the VCSEL reflectivity because of the metal Au deposited on DBR. The reflectivity and photoluminescence (PL) spectra measured from the metallic bonded samples fore-and-aft indicated that the process of Au-In-Au low temperature metallic bonding had rarely impacted on the optical performances of the active region and DBR, which would be favorable to the structure fabrication of VCSEL.Multiple quantum well active region electroluminescent devices and bonding structural 1.3μm VCSEL devices which were fabricated in III-V compound semiconductor process flat were studied. The device processes mainly include direct bonding, platform facture, lateral etching, insulating, p-side electrode forming, n-side electrode forming, and so on. For electroluminescence devices, the unsealed voltage was about 1.1V, and the luminescent wavelength was 1.31μm. For bonding structural 1.3μm VCSEL devices, the unlocked voltage was about 3.8V with the resistance of 2.4*10³Ω, and they were lasing at 1288. 63nm with 13.88mA pulse current (duty ratio: 0.5%) at room temperature.