Surface plasmon lasing in semiconductor gain media at far-infrared frequencies requires simultaneously long non-radiative recombination times and large plasmon propagation length. In this paper, we show that these conditions are realized in mercury-telluride quantum wells (HgTe QWs) near the topological transition. We derive the conditions of surface plasmon amplification in HgTe QWs with interband population inversion. To this end, we calculate the spatially-dispersive high-frequency conductivity of pumped HgTe QWs taking into account their realistic band structure, and compare the interband gain with Drude absorption and collisionless Landau damping. An extra necessary condition of plasmon lasing is revealed, namely, the non-equilibrium carrier density should be high enough to make the plasmon spectrum overlap with the frequency domain of interband excitations. The latter condition limits the processes of both stimulated and spontaneous plasmon emission at low temperatures, and should have a strong impact on the recombination kinetics of HgTe QWs at low temperatures.

We report on the stimulated emission (SE) from HgTe/CdHgTe quantum well (QW) heterostructures up to 240 K at 3.7 μm wavelength. Based on the temperature dependence of the SE threshold, a total Auger recombination (AR) coefficient of 10−27 cm6/s has been deduced for HgTe/CdHgTe QWs, which is much lower than that for bulk HgCdTe with the same bandgap and indicates suppression of (threshold) AR processes due to the symmetry of carrier dispersion curves. We demonstrate that QW-specific, non-threshold AR contributes strongly to the temperature quenching of laser action from HgTe/CdHgTe QWs. We expect, however, that the above processes may be partially suppressed via introduction of wide-gap CdHgTe barrier layers with a [Cd] fraction of 80% or higher. In this case, lasing up to at least 270 K at 3.7 μm wavelength seems feasible.

Recent progress in the molecular beam epitaxy (MBE) of CdHgTe/HgTe quantum well (QW) heterostructures paves the way to a new generation of photodetectors, light-emitting diodes and lasers [1,2]. A remarkable feature of such structures is the ability to suppress the Auger recombination in narrow (<10 nm) QWs in contrast to bulk-like wells [3]. In conjunction with a variable bandgap (from 0 to 1.5 eV), this feature allows developing long-wavelength lasers on interband transitions. Such lasers could be of use in 3.5-4.5 µm and 8-13.5 µm wavelength bands, corresponding to the atmospheric transparency windows, as well as in 25-50 µm range, where no quantum cascade lasers (QCLs) are available as yet. Coherent radiation from a HgCdTe (MCT) bulk alloy was first obtained in 1966 [4], 4 years after the very first semiconductor laser had appeared [5]. Interest in stimulated emission (SE) from MCT was revived in the 1990s [6,7], when the MCT growth technology was developing rapidly for the mid-infrared (IR) detectors [8]. However, this interest faded quickly, most likely due to the fast progress of mid-IR QCLs, happening about the same time. By 2015, the longest wavelength of coherent radiation obtained from MCT was 5.3 µm [6]. In recent years, some progress has been made as far as coherent radiation from MCT material is concerned [9][10][11]: in particular, SE up to ~20 µm has been demonstrated in [9]. The possibility of optical gain in HgCdTe QWs in 20-60 µm range has been already theoretically predicted [12]. However, for the development of lasers and photodetectors, scrutiny of carrier recombination is of paramount importance. CdHgTe/HgTe QW structures were poorly studied in this respect, especially as far as narrow-gap QWs are

In this work we report, to the best of our knowledge, the first quantum well electrically-pumped microdisk lasers monolithically deposited on (001)-oriented Si substrate. The III-V laser structure was epitaxially grown by MOCVD on silicon with an intermediate MBE-grown Ge buffer. Microlasers with an InGaAs/GaAs quantum well active region were tested at room temperature. Under pulsed injection, lasing is achieved in microlasers with diameters of 23, 27, and 31 µm with a minimal threshold current density of 28 kA/cm. Lasing spectrum is predominantly single-mode with a dominant mode linewidth as narrow as 35 pm.