Electronic bandstructure and optical gain of lattice matched III-V dilute nitride bismide quantum wells for 1.55 μm optical communication systems

Abstract

Dilute nitride bismide GaNBiAs is a potential semiconductor alloy for near-and mid-infrared applications, particularly in 1.55 µm optical communication systems. Incorporating dilute amounts of Bismuth (Bi) into GaAs reduces the effective bandgap rapidly, while significantly increasing the spin-orbit-splitting energy. Additional incorporation of dilute amounts of Nitrogen (N) helps to attain lattice matching with GaAs, while providing a route for flexible bandgap tuning. Here we present a study of the electronic bandstructure and optical gain of the lattice matched GaN x Bi y As 1−x−y /GaAs quaternary alloy quantum well (QW) based on the 16-band k·p model. We have taken into consideration the interactions between the N and Bi impurity states with the host material based on the band anticrossing (BAC) and valence band anticrossing (VBAC) model. The optical gain calculation is based on the density matrix theory. We have considered different lattice matched GaNBiAs QW cases and studied their energy dispersion curves, optical gain spectrum, maximum optical gain and differential gain; and compared their performances based on these factors. The thickness and composition of these QWs were varied in order to keep the emission peak fixed at 1.55 µm. The well thickness has an effect on the spectral width of the gain curves. On the other hand, a variation in the injection carrier density has different effects on the maximum gain and differential gain of QWs of varying thicknesses. Among the cases studied, we found that the 6.3 nm thick GaN 3 Bi 5.17 As 91.83 lattice matched QW was most suited for 1.55 µm (0.8 eV) GaAs-based photonic applications.

Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells

“…Moreover, we also need six additional bands to incorporate the local Bi resonant p-like states with freedom of spin, including spin-orbital coupling [16]. According to the methodology introduced in [16,27,30,31] whereH 8 8 is the 8-band · k p Hamiltonian of host material given by equation (2) [32],H 2 2 is the s-like localized N impurity Hamiltonian [22] andH 6 6 is the Hamiltonian for the p-like localized Bi impurity [27]. TheH 8 2 andH 6 8 account for the interaction between N and Bi impurity resonate states with the host material states [20,27].…”

“…The presence of both N and Bi doped impurities in InSb makes the band inversion easier to realize, and has a twofold advantage: (i) firstly, the conduction band (CB) edge has a negative shift (lowering of CB edge) due to N doping, while the valence band (VB) edge has a positive shift (lifting of VB edge) due to Bi doping. These two phenomenon occur simultaneously and independently of each other [16], which greatly increases the possibility of band inversion, if appropriate proportion of N and Bi were doped. (ii) Secondly, the doping of N alone induces tensile strain (e >  0), while Bi alone induces compressive strain (e <  0), both of which are a concern for lattice growth by molecular beam epitaxy or metal organic chemical vapor deposition.…”

“…It has been experimentally shown that, by varying the composition of N and Bi, the band gap of can be tuned to be near zero and even negative [17,18]. This can be theoretically explained by the band anticrossing (BAC) model [16,[19][20][21]. The N-related resonant states couple with the CB and lowers the CB edge [22].…”

Semiconductor quantum nanostructures for optoelectronic applications

“…This is followed by SO1 in 4 and 6 ML. Also note that as the NPL thickness increases, the spread of the TME intensity in the k-space decreases [78]. Owing to the microscopic selection rules for the TM polarization mode associated with the unit cell wavefunctions, the HH to E transitions are forbidden, while only LH to E transitions are allowed.…”

“…The presence of both N and Bi doped impurities in InSb makes the band inversion easier to realize, and has a twofold advantage: (i) Firstly, the conduction band (CB) edge has a negative shift (lowering of CB edge) due to N doping, while the valence band (VB) edge has a positive shift (lifting of VB edge) due to Bi doping. These two phenomenon occur simultaneously and independently of each other [78], which greatly increases the possibility of band inversion, if appropriate proportion of N and Bi were doped. (ii) Secondly, the doping of N alone induces tensile strain (ε > 0), while Bi alone induces compressive strain (ε < 0), both of which are a concern for lattice growth by molecular beam epitaxy or metal organic chemical vapor deposition.…”