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BGa(As)P alloys for III-V integration on silicon (Conference Presentation)

Monolithic growth of III-V semiconductors on silicon is a promising path for the development of silicon-based lasers. The GaP binary has a lattice constant very close to that of silicon and can be grown defect free without anti-phase domains (APDs) or stacking faults on (001) exact orientated silicon substrates. These GaP on Si templates provide the base for growth and investigation of III-V lasers. The addition of boron can be used to partially replace Ga and further reduce the lattice constant. This can be balanced to match the lattice constant of silicon by adding As to partially replace P. The alloying also provides control of band gaps and band offsets as well as refractive index. The BxGa(1-x)P and BxGa(1-x)AsyP(1-y) alloys are being explored to provide lattice matching/ strain compensation, cladding and the Separate Confined Heterostructure (SCH). The effects of the inclusion of boron on device related alloy properties have not been studied extensively and are not well understood. We investigate the refractive index and extinction coefficient dispersion relation and the electronic band structure properties of these boron containing alloys using spectroscopic ellipsometry to provide inputs for device modelling and optimisation. Results from the spectroscopic ellipsometry are presented for a series of BGaP and BGaAsP alloy samples with boron fractions in the range 0-6.6% and arsenic fractions from 0-17% on GaP substrates and GaP/ Si templates. These results provide important information for the design of lasers with strong optical and electronic confinement, as shall be discussed.