TY - GEN
T1 - Tight binding analysis of the electronic structure of dilute bismide and nitride alloys of GaAs
AU - Broderick, C. A.
AU - Usman, M.
AU - Lindsay, A.
AU - O'Reilly, E. P.
PY - 2011
Y1 - 2011
N2 - We use a nearest-neighbour sp3s* tight-binding Hamiltonian to investigate the electronic structure of GaAs-based dilute bismide and bismide-nitride alloys. We show that the observed strong variation of the band gap (Eg) and spin-orbit splitting energy (ΔSO) with Bi composition in GaBixAs1-x is due primarily to a band-anticrossing interaction between the extended states of the host matrix valence band maximum and highly localised Bi-related defect states lying in the valence band, with the change in Eg also having a significant contribution from a conventional alloy reduction in the conduction band edge energy. We calculate a crossover to an Eg < Δ SO regime at approximately 10.5% Bi composition in bulk GaBixAs 1-x, in agreement with recent experimental studies of GaBi xAs1-x epilayers grown on GaAs. Finally, we present calculations which show that the effects of N and of Bi are largely independent of each other in random GaBixNyAs1-x-y alloys, of relevance for future high efficiency photonic devices.
AB - We use a nearest-neighbour sp3s* tight-binding Hamiltonian to investigate the electronic structure of GaAs-based dilute bismide and bismide-nitride alloys. We show that the observed strong variation of the band gap (Eg) and spin-orbit splitting energy (ΔSO) with Bi composition in GaBixAs1-x is due primarily to a band-anticrossing interaction between the extended states of the host matrix valence band maximum and highly localised Bi-related defect states lying in the valence band, with the change in Eg also having a significant contribution from a conventional alloy reduction in the conduction band edge energy. We calculate a crossover to an Eg < Δ SO regime at approximately 10.5% Bi composition in bulk GaBixAs 1-x, in agreement with recent experimental studies of GaBi xAs1-x epilayers grown on GaAs. Finally, we present calculations which show that the effects of N and of Bi are largely independent of each other in random GaBixNyAs1-x-y alloys, of relevance for future high efficiency photonic devices.
KW - band anti-crossing
KW - dilute bismide alloy
KW - dilute nitride alloy
KW - Electronic structure
KW - tight-binding
UR - https://www.scopus.com/pages/publications/80155183250
U2 - 10.1109/ICTON.2011.5970828
DO - 10.1109/ICTON.2011.5970828
M3 - Conference proceeding
AN - SCOPUS:80155183250
SN - 9781457708800
T3 - International Conference on Transparent Optical Networks
BT - 2011 13th International Conference on Transparent Optical Networks, ICTON 2011
T2 - 2011 13th International Conference on Transparent Optical Networks, ICTON 2011
Y2 - 26 June 2011 through 30 June 2011
ER -