Abstract
This thesis focuses on exploring novel III-V bismide alloys due to their potential of engineering the band structure in such a way that the spin-orbit splitting energy is greater than the band gap [ΔSO > Eg) which helps to suppress important non-radiative Auger recombination losses. These losses reduce the efficiency of near-IR telecommunication lasers (1. 55μm) as well as limit the performance of mid-IR light emitting devices. A number of optical characterisation techniques have been applied to study the detailed band structure of bismide alloys to provide feedback for band structure modelling and growth optimisation. PR studies on the GaBixAs1-x/GaAs material system with up to 10. 4% Bi, showed a strong Eg reduction accompanied by an increase in ΔSO with increasing Bi content, with a cross-over of Eg and ΔSO at Bi ~ 9. 4. +0. 2%. RT PL emission has been measured at telecom wavelength (1. 5 pm) with Bi ~ 10. 4 %. Power dependent PL studies showed tentative evidence for the suppression of CHSH Auger losses in the 10. 4% Bi containing sample. The InGaAsBi/InP alloy has been explored for its potential for cheap and efficient mid-IR photonic devices. PL, PR and absorption revealed the cross-over (ΔSO~Eg) in this material system between ~ 3. 4 - 4% Bi. Temperature dependent PR studies for the highest Bi containing InGaAsBi (~5%) and GaAsBi (~10. 4%) epilayers were used to tune the band gap into resonance Aso ~ Eg and an increase in the line width of the PR spectrum around the temperature of the resonance is found. Another alloy GaAsBiN/GaAs has been suggested to provide a lattice matched material to GaAs with widely tailored Eg while offering improved conduction and valence band offsets. PR measurements on GaAsBiN/GaAs showed a reduction in Eg around -141 +- 22meV/%N at a fixed Bi composition and also a decrease in the temperature coefficient with increasing N.