Aluminum gallium arsenide-indium gallium arsenide crystal growth, buried tunnel contact lasers, wafer bonding, and alluminum gallium arsenide oxide-based VCSELs

In this work the crystal growth, growth calibration, and device fabrication of AlGaAs semiconductor and native oxide materials for use in semiconductor laser diodes employing buried tunnel contacts and wafer bonding are described. The AlGaAs native oxide is used to guide both current and photons via apertures and highly reflective semiconductor/oxide mirrors and interfaces in both edge-emitting and vertical cavity surface-emitting laser diodes (VCSELs). Highly reflective mirrors define thin vertical cavities which increase coupling of gain to the lasing mode and reduce thresholds in both edge-emitting lasers and in VCSELs. Lateral electron currents feed reverse-biased tunnel contact junctions "underneath" the insulating oxide-defined mirrors in order to excite the laser active region (inject holes) while minimizing the amount of material needed for current spreading. In order to realize buried tunnel contact junction VCSELs, various crystal growth, material, and device optimization procedures are required and are described.; In order to overcome the inherent limitations of epitaxial material grown on a single substrate, wafer bonding has been developed over the last decade and is now introduced to the Solid State Devices Laboratory. Resistors are formed by simply bonding two n-type substrates together in order to optimize wafer preparation and bonding parameters. Tunnel junctions are inserted at various distances from the bonding interface to monitor the degree of annealing and disordering that occurs during wafer bonding. The wafer bonding work is the basis for fabricating more sophisticated device structures including light-emitting diodes (LEDs) and VCSELs employing buried tunnel contact junctions.