Development of wafer bonded vertical cavity surface emitting lasers

This thesis describes the development of wafer bonded vertical cavity surface emitting lasers. By employing a reactive low temperature bonding technique, we have successfully demonstrated oxide-defined 850 nm vertical-cavity surface-emitting lasers (VCSELs) on silicon substrates. In this dissertation the design, fabrication, characterization, and applications of wafer bonded vertical cavity surface emitting lasers have been studied.; The reactive low temperature bonding technique have been studied and various bonding conditions have been tried in order to find the optimal parameter window.; Selective wet oxidation procedure has been used to define the aperture region of the VCSELs. The electrically insulating low refractive index oxide layers within the VCSEL confine both electrons and photons quite effectively, and thus serve to define the transverse laser cavity.; Fabricated VCSELs on silicon substrate have been put through several experiments for device calibration. The high output power and differential quantum efficiency were partially enabled by the higher thermal conductance of the Si substrate and the low thermal resistance of the bonding interface.; Relative intensity noise measurements have been carried out in details with the fabricated devices. Purposely excluding the parasitic effects, the influence of multi-mode operation of the laser to the relaxation resonance frequency and the modulation speed has been studied. Appearance of multiple modes may reduce the VCSEL modulation speed significantly, however, very high coupling between these different modes might result in single relaxation resonance frequency, similar to that of a single mode laser. Therefore, VCSELs on Si with the low-temperature bonding process present the potential for high-speed modulation.; Optical spectra of VCSEL at different bias current have also been measured, as well as the thermal characteristics of these devices.; In addition, current density and carrier concentration distribution in wafer bonded VCSELs with dielectric top mirrors have been numerically simulated. The analysis demonstrates that current confinement for p-mirror VCSELs is approximately twice as effective as the corresponding n-mirror VCSELs. Although current confinement improves with increasing aperture size, the property of optical modal distribution deteriorates. The achievement of the best device performance will depend on how well the “ideal” device structure, where the current confinement region is right next to the quantum-well region, can be realized.