Ellipsometry data for Multisubband Plasmons in InAsGaSb Broken Gap Quantum Well

The experimental spectroscopic ellipsometry data Ψ and ∆ obtained from 1.7 to 40 μm using an IR-VASE instrument from J.A. Woollam. The systems measured were:(1.) 500 μm thick Te-doped GaSb (6.5 ×10^17 cm^−3) substrate.(2.) the substrate as in (1.) but a 300 nm unintentionally doped GaSb buffer layer (2−3×10^16 cm^−3) grown on the top.(3.) the systems as in (2.) but with one of the GaSb(10 nm)/InAs(L_InAs)/GaSb(10 nm) quantum well nanostructures grown on the top, with • L_InAs = 8 nm and ne = 1.22 × 10^19 cm^−3 (bulk well doping)• L_InAs = 18 nm and ne = 1.02 × 10^19 cm^−3 (bulk well doping) Before taking the measurements, the back side of the GaSb substrate of all samples was carefully depolished using 5-micron alumina particles. The experimental data for all samples were collected at two incidence angles (50 deg and 70 deg) under optimized conditions to improve the quality of the results. The number of scans was increased to 500 to improve the signal-to-noise ratio, and the resolution was set to 8 cm^−1 to resolve fine spectral features.