-0.3 eV band gap value [@Dimmock1966]. Variation of Tin content in $\text{Pb}_{1-x}\text{Sn}_{x}\text{Te}$ ($\text{Pb}_{1-x}\text{Sn}_{x}\text{Se}$) alloy result in similar physics as for $\text{Hg}_{1-x}\text{Cd}_{x}\text{Te}$ alloys, i.e., linear dispersion law.

2DEG in chalcogenide materials is usually achieved in heterostructures containing a QW. These heterostructures are made of semiconductors with unequal band gaps, so the resulting band structure can be adjusted to one’s need by an engineered layering of different materials [@Henini2013]. Such layered structures are usually fabricated with the use of the molecular beam epitaxy (MBE) technique, which allows growing thin films with atomic precision. To restrict the motion of carriers to a 2D plane a confining potential is needed. Confinement is achieved either in type I heterojunctions together with doping of the wider band gap semiconductor, or in QW structures. In a QW structure, a lower band gap semiconductor layer is sandwiched between wider band gap semiconductor layers. A standard way to separate free charge carriers and charged impurities is the modulation-doping scheme [@Dingle1978]. In such a scheme, dopants are spatially separated from the confining potential well. Thus, carrier scattering at ionized impurities (donors and acceptors) is greatly reduced, which results in higher low-temperature carrier mobility — a conventional measure of 2DEG quality.

