Sb-based materials rely on the GaSb, InAs, AlSb, InSb binary compounds and their quaternary or pentanary alloys (AlGaAsSb, GaInAsSb, AlGaInAsSb,.. ). This technology exhibits several distinctive properties as compared to other semiconductors: type-I to type-III band alignments, giant band offsets, low effective masses of electrons and holes, direct bandgaps between 0.15 and 1.7 eV.
Conventional laser diodes (LDs) rely essentially on GaInAsSb type-I quantum wells (QWs) confined by AlGa(In)AsSb barrier layers. Low threshold currents and high T0 have been demonstrated between 1.5 and 3.4 µm. The AlGaInAsSb pentanary barrier is needed to extend the wavelength beyond 3 µm while keeping a type-I band alignment  even though it makes the epitaxial growth complex. Single mode operation has been achieved with both DFB lasers and VCSELs using the same active zone. At longer wavelength, interband cascade lasers (ICLs) based on GaInSb/InAs type-II p-n junctions stacked in series exhibit room temperature cw emission between 3.5 and 5 µm, including single mode operation of DFB lasers. At still longer wavelength InAs/AlSb quantum cascade lasers (QCLs) benefit from the low InAs effective mass and giant conduction band offset. High performance have been demonstrated all the way from 2.6 µm up to 25 µm, particularly at long wavelength which is an asset of this technology.
The evolution toward smart, integrated, sensors requires integrating III-V optoelectronic devices with Si-based platforms. The epitaxial growth of III-V compounds on Si has thus been the focus of renewed attention for about a decade now. We have shown that the Si substrate preparation and the III-Sb nucleation on Si are crucial steps. This allowed us demonstrating a variety of epitaxially integrated optoelectronic devices such as laser diodes, photodetectors and the first ever QCL grown on Si. In this presentation we review the recent results obtained on the integration of antimonide-based QCLs epitaxially grown on Si substrates. We will show that this technology is very attractive for future III-V on Si integration, and we will discuss future integration schemes.
Bandgap engineering, by means of alloying or inserting nanostructures, is the bedrock of high efficiency photovoltaics. III-V quaternary alloys in particular enable bandgap tailoring of a multi-junction subcell while conserving a single lattice parameter. Among the possible candidates, AlInAsSb could in theory reach the widest range of bandgap energies while being lattice-matched to InP or GaSb. Although these material systems are still emerging photovoltaic segments, they do offer advantages for multi-junction design. GaSbbased structures in particular can make use of highly efficient GaSb/InAs tunnel junctions to connect the subcells. There has been only little information concerning GaSb-lattice matched AlInAsSb in the literature. The alloy’s miscibility gap can be circumvented by the use of non-equilibrium techniques. Nevertheless, appropriate growth conditions remain to be found in order to produce a stable alloy. Furthermore, the abnormally low bandgap energies reported for the material need to be confirmed and interpreted with a multi-junction perspective. In this work, we propose a tandem structure made of an AlInAsSb top cell and a GaSb bottom cell. An epitaxy study of the AlInAsSb alloy lattice-matched to GaSb was first performed. The subcells were then grown and processed. The GaSb subcell yielded an efficiency of 5.9% under 1 sun and the tandem cell is under optimization. Preliminary results are presented in this document.