The aim is to reduce the non radiative recombination (particularly the Auger recombination) seen in non strained structures, with use of band engineering techniques in the active region, applied to III-V antimonides, exploiting known strain effect in antimonides. The cladding region and the contacts will also be optimised with epitaxial growth. It is hoped to advance the state of 3-5um emitters, either in IV-VI or III-V materials, with use of multilayer zero net strain effects, to enable the highest operational temperature, specifically aimed at removing the need to cool below room temperature. With such an improvement over lead salts and non strained antimonides, this could lead on to consolidation of devices, using carrier extraction techniques as an option to reduce fundamental recombination dependent on carrier numbers. The second phase work would develop the component technology further, both experimentally and theoretically and assess the application for future microelectronic and microsystems product.
The work would compare efficiency of two candidate zero net strain superlattice structures in antimonides optimised to 2um, with a conventional structure with optimum performance at that wavelength and then move to longer wavelengths, corresponding to the gas sensing wavelengths of interest. The temperature dependence of the photoluminescence would be studied to infer improvement of the band engineering effects on Auger reduction, and later electroluminescence of devices. If successful at device level some demonstrators will be made to assess market interest.
The project is to investigate feasibility of realising low cost tuneable mid-infrared injection lasers, fabricated with Sb-containing III-V materials, targeting good performance at room temperature. It focuses on use of semiconductor band engineering, particularly strained layer techniques, to surpress non radiative recombination paths, and to provide optimum cladding and contact layers. If successful in phase one, the development of the devices and investigation of their application to aspects of 1) process monitoring 2) environmental measurement and control and 3) medical gas monitoring prototypes, is predicted for phase two.