Study of excitonic gas within InAs/Al_0.2Ga_0.8Sb based broken gap QW system

InAs/GaSb based heterostructure known to be a broken gap type-II quantum well (QW) system, possibly hosting 2D case of topological insulating material. We investigated InAs/Al_0.2Ga_0.8Sb type-II QW system features with the purpose of understanding the reasons behind the measured signals from such a sample through THz magneto-photoresponse spectroscopy at low magnetic field region (0.5<B<1.5 T) at cryogenic temperature (1.4 K). The 10 nm thick InAs QW sandwiched asymmetrically between Al_0.2Ga_0.8Sb layers (as shown in Fig.1) has a sheet density of 7.33×10¹¹ cm^-2. Due to band alignment for such a QW system there exist a possibility of forming excitonic gas at the interface layers [1] which could ultimately change the properties of 2DEGs confined within QW system. Through solving 8×8 Kane model Hamiltonian of such a system including all the related effective mechanisms (including strain, SOC) experimental results have been analyzed. We plan to present our findings for the InAs/Al_0.2Ga_0.8Sb based heterostructure at coming APS march meeting.