Photoluminescence spectroscopy of HgCdTe quantum well heterostructures in the 15–30 $\mu$m wavelength range

In recent years, narrow gap heterostructures with Hg$_{1-x}$Cd$_x$Te/Cd$_y$Hg$_{1-y}$Te quantum wells have been actively studied both in connection with the topic of topological insulators and from the point of view of their application in optoelectronics in the terahertz domain. In this work, we study the photoconductivity and photoluminescence spectra of structure with a band gap of 40 meV. In addition to interband transitions, the features of the spectra associated with the resonance states of acceptors have been identified. The possibilities of using the structures under study to develop interband emitters at a wavelength of $\sim$30 $\mu$m, which is inaccessible to existing quantum-cascade lasers, are discussed.