Sb-based laser sources grown by molecular beam epitaxy on silicon substrates

The material system comprising GaSb, InAs, AlSb and their related alloys are an impressive toolbox for device designers, as they offer a very large choice of band-gaps and band offsets. Molecular beam epitaxy (MBE) and device processing have been improving quickly over recent years, allowing the fabrication of high performance devices as quantum cascade lasers, mid-infrared (MIR) edge emitting and surface emitting lasers, superlattice infrared photodetectors, but also very high speed / low consumption AlSb/InAs field effect transistors. Efforts have been made to monolithically grow these devices onto larger and cheaper substrates like GaAs and Si, to improve the yield / decrease the cost of this technology and possibly integrate the devices with CMOS technology. We recently fabricated a 2.3 μm edge emitting laser grown by MBE on a Si substrate, and demonstrated roomtemperature pulsed operation. Lasers emitting at this wavelength are of particular interest for gas sensing. Challenges to further improve the device include the substrate preparation, optimization of the nucleation layer quality, but also the conduction band engineering in order to facilitate the electronic transport at the Si/III-Sb interface.