Determine Luttinger parameters for SiGeSn alloys

Determine the Luttinger parameters of SiGeSn alloys with varying compositions to enable more accurate band-structure modeling of SiGeSn-based quantum devices.

Background

The proposed switchable heavy-hole/light-hole qubit is modeled using the six-band Luttinger-Kohn-Bir-Pikus Hamiltonian. The Luttinger parameters $\gamma_1$, $\gamma_2$, and $\gamma_3$ determine the valence-band dispersion and effective masses, and therefore affect the calculated heavy-hole/light-hole confinement, mixing, $g$-factors, orbital splittings, and qubit-control properties.

The paper states that reliable composition-dependent Luttinger parameters for SiGeSn barriers are not established. Consequently, the calculations use the Ge Luttinger parameters throughout the heterostructure as an approximation. Establishing these alloy parameters is identified as a necessary next step for refining theoretical descriptions of SiGeSn-based quantum devices.