436 ISSN 1063-7826, Semiconductors, 2018, Vol. 52, No. 4, pp. 436–441. © Pleiades Publishing, Ltd., 2018. Magnetooptical Studies and Stimulated Emission in Narrow Gap HgTe/CdHgTe Structures in the Very Long Wavelength Infrared Range 1 V. V. Rumyantsev a, b *, L. S. Bovkun a,c , A. M. Kadykov a, g , M. A. Fadeev a , A. A. Dubinov a, b , V. Ya. Aleshkin a, b , N. N. Mikhailov d, e , S. A. Dvoretsky d , B. Piot c , M. Orlita c, f , M. Potemski c , F. Teppe g , S. V. Morozov a, b , and V. I. Gavrilenko a, b a Institute for Physics of Microstructures of Russian Academy of Science, Nizhny Novgorod, 603950 Russia b Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603950 Russia c Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS-UGA-UPS-INSA-EMFL, Grenoble, 38042 France d A. V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, 630090 Russia e Novosibirsk State University, Novosibirsk, 630090 Russia f Institute of Physics, Charles University, Prague, 12116 Czech Republic g UMR CNRS 5221, GIS-TERALAB, Université Montpellier, Montpellier, 34095 France *e-mail: rumyantsev@ipmras.ru Received December 25, 2017 Abstract—We investigate the prospects of HgTe/HgCdTe quantum wells for long-wavelength interband lasers (λ = 15–30 μm). The properties of stimulated emission (SE) and magnetoabsorbtion data of QWs structures with wide-gap HgCdTe dielectric waveguide provide an insight on dominating non-radiative carrier recom- bination mechanism. It is shown that the carrier heating under intense optical pumping is the main factor lim- iting the SE wavelength and intensity, since the Auger recombination is greatly enhanced when carriers pop- ulate high energy states in the valence band. DOI: 10.1134/S1063782618040255 In recent years, narrow gap HgTe/CdHgTe quan- tum wells (QWs) have been studied intensively due to a number of their peculiar fundamental properties. It is well known that when the HgTe QW width is increased the band ordering in the QW changes from the normal one (like in CdTe) to the inverted ordering, in which hole-like subband lies higher in energy than electron-like subband [1]. Such inverted band struc- ture occurs for QW widths exceeding the critical one: d c ~ 6.3 nm, at which the carrier spectrum in QW is linear, resembling that of graphene. Therefore, while QWs with the inverted band structure were identified as the very first 2D topological insulators [2, 3], the narrow gap (and even gapless) HgTe/CdHgTe QWs with high carrier mobility are of interest for terahertz (THz) optoelectronics [4]. Indeed, a number of prop- erties relevant for graphene structures as a promising candidate for THz lasers [5–7] and sensors [8], can be exploited in HgTe/CdHgTe QWs as well, due to simi- larities in the carrier spectra. In particular, linear car- rier spectrum of graphene was believed to prohibit the Auger recombination, probably the main obstacle in developing THz emitters, which is one of the hottest topics in the applied physics. However, there is still some debate concerning the effectiveness of the Auger recombination in graphene structures, because the marginal case of relativistic spectrum with zero band- gap and linear dispersion law requires rigorous consid- eration [9]. In contrast to graphene, HgTe/CdHgTe QW allow opening the bandgap in a natural way: by changing the QW width or just varying temperature. At the same time, the carrier spectrum remains quasi- symmetrical and strongly non-parabolic in the vicinity of the Γ point, allowing one to expect that Auger recombination is suppressed in HgTe/CdHgTe QW as well. Indeed, when compared to graphene, HgTe/CdHgTe QW with bandgap of 25 meV demonstrate the carrier lifetime that is as order of magnitude higher [4]. Admittedly, phonon frequencies in MCT materials are much lower than that of graphene: HgTe-like phonon has the energy of 15 meV, while CdTe-like phonon has 1 The article is published in the original. XXV INTERNATIONAL SYMPOSIUM “NANOSTRUCTURES: PHYSICS AND TECHNOLOGY”, SAINT PETERSBURG, JUNE 26–30, 2017. OPTOELECTRONICS, OPTICAL PROPERTIES