Molecular beam epitaxy and technology for the monolithic integration of quantum well lasers and AlGaAs/GaAs/AlGaAs-HEMT electronics

In this presentation the various technology steps for the monolithic integration of GaAs quantum well lasers with Double Pulse Doped AlGaAs/GaAs/AlGaAs Quantum Well E/D HEMT electronics on a single substrate in one process run are described. All layers are grown by molecular beam epitaxy in an Intevac Gen II system. The laser structure, consisting of three 74 Angström GaAs quantum wells between two AlGaAs cladding layers, are grown on top of the electronic structure. The laser mesas and contact areas are defined by a combined wet and dry etch process. Apart from the transistor gates which are exposed by electron beam lithography, all photolithography steps are performed using contact printing. To interconnect the devices a two layer metallization is used whereby air-bridges are used to connect the laser mesas to the electronics. Several designs of laser diode drivers and laser diodes were processed in this run. The results showed good performance of the electronic devices, and a high l uminescence yield (bigger than 90 percent) for the laser diodes measured on-wafer. Some chips were cleaved to obtain laser mirrors. For these chips functional lasers were shown for laser diodes of area 4 x 360 my square m with threshold currents in the range of 20 to 30 mA, as well as the operation of laser diode drivers integrated with laser diodes operating at a data rate of 7.4 Gbit/sec.