HgCdTe-based heterostructures with quantum wells are a promising material for semiconductor lasers in the atmospheric transparency window (3–5 µm) thanks to the possibility of suppressing Auger recombination. In this work, we demonstrate room temperature stimulated emission at 3.67 µm wavelength from HgCdTe heterostructures with quantum wells under optical pumping. We experimentally determine the temperature dependence of effective Auger coefficient in the studied structures and reveal its unusual non-monotonous behavior which is explained by the interplay between activated and non-threshold Auger processes. The performance of the studied samples appears comparable to those of non-cascade III-V type-I QW laser sources, and so interband HgTe/CdHgTe QW lasers mark another step toward integrated mid-IR range HgCdTe optoelectronic devices.

Impact ionization probabilities were calculated in a CdHgTe quantum well, where the distance between electron subbands is close to the band gap energy. This band structure enables impact ionization with small momentum transfer for electrons in the second subband. The study demonstrates that such processes increase the impact ionization probability by approximately two orders of magnitude compared to the impact ionization probability for electrons in the first subband, for which transitions with small momentum changes are impossible. The probability of single impact ionization during the electron energy loss due to optical phonon emission is estimated. Experimental methods for detecting impact ionization in this structure are discussed.

Long-wavelength infrared photoconductivity spectra have been studied in epitaxial films of Hg1–xCdxTe solid solutions with a narrow band gap (from zero to 10 meV) at liquid helium temperatures. Because all doubly charged mercury vacancies are neutral under these conditions, lines unrelated to singly ionized mercury vacancies have been identified among the optical transitions to resonant states of acceptors in the conduction band. An applied magnetic field results in the appearance of/increase in the band gap and the transformation of resonant states of acceptors into localized ones, which leads to a multiple decrease in the amplitude of lines in the photoconductivity spectra due to the large difference in the carrier mobility between the conduction and valence bands.

A theoretical study of influence of doping on plasmon–phonon gain in donor-doped HgTe/CdHgTe heterostructures with a single HgTe quantum well (QW) under optical excitation conditions was carried out. The dependences of the threshold concentration of nonequilibrium carriers on the concentration of equilibrium electrons in the QW were calculated. The concentration of equilibrium electrons in the QW that corresponds to the minimum threshold excitation power density was found.

Lasing from HgCdTe microdisk cavities is demonstrated at wavelengths as long as 20–25 μm. The optical threshold and operation temperature are mainly limited by nonradiative Shockley–Read–Hall type recombination. The employed ion etching technology appears to introduce additional defects in the vicinity of the microdisks, degrading figures of merit as the height of the cavity increases. However, a watt-level mid-infrared pumping source should suffice for lasing in microdisks with a height of ∼3 and ∼100 μm diameter.

A model for calculating the Auger recombination rate in narrow-gap quantum wells of HgTe/CdHgTe heterostructures has been developed. It has been shown that for correct calculation of the Auger recombination rate in such structures, it is necessary to take into account the impact ionization processes and the influence of free carriers on the electron-electron interaction. It has been found that the presence of free carriers can both increase and decrease the Auger recombination rate depending on the carrier concentration. The dependences of the recombination rate for quantum wells with a bandgap of 35 and 50 meV on the concentration of nonequilibrium carriers at four temperatures 8, 100, 200, and 300 K have been found. The Auger recombination rates have been found at concentrations corresponding to the light transparency of quantum wells and threshold carrier concentrations for laser generation. Estimates are given for the values of threshold current densities and threshold power densities of the exciting radiation. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial NoDerivs 4.0 International (CC BY-NC-ND) license (https://creativecommons.org/licenses/by-nc-nd/4.0/). https://doi.org/10.1063/5.0288802

We propose a compact two-color HgCdTe laser capable of operating under optical pumping with a near-infrared semiconductor diode. The gain, distribution of electromagnetic fields, losses, and generation thresholds are calculated for the laser design containing two arrays of quantum wells (QWs). The design originality is to use the intracavity laser radiation at an intermediate wavelength in the mid-infrared so that carrier heating is avoided in the QW array that provides long-wavelength emission. The possibility of lasing at wavelengths of 10.3 and 28.2 μm under pump intensity slightly above 1 W/cm2 at a wavelength of 1 μm is shown. Low generation threshold suggests the proposed laser should be able to operate in a continuous wave mode at cryogenic temperature.

Spectral studies of the photoconductivity in the temperature range of T = 5–70 K, as well as studies of the magneto-absorption and magnetotransport at T = 4.2 K, have been performed in a HgTe/CdHgTe heterostructure with a double quantum well under an “optical gate” effect. Studies of magneto-absorption spectra under the controlled optical exposure have made it possible to observe absorption lines caused by both the cyclotron resonances of electrons and holes simultaneously. The coexistence of electrons and holes in the HgTe/CdHgTe double quantum well with a relatively large bandgap ( 80 meV) indicates the appearance of a strongly inhomogeneous light-induced distribution of charge carriers in the plane of the structure. Experimental results obtained clearly demonstrate disadvantages of the control of the Fermi level positions in heterostructures with HgTe/CdHgTe quantum wells by means of the optical gate.

The work is devoted to the study of plasmon-phonon gain in CdHgTe/HgTe structures with quantum wells (QWs) located near the boundary of the structure with vacuum/air (near-surface QWs). The issue of the influence of the distance between QWs on the plasmon-phonon gain has been studied. It has been shown that a decrease in the distance from the nearest QW to the structure boundary leads to an increase in the phase velocity of the generated plasmon-phonon and a decrease in the power absorbed by phonons in the barriers. This leads to a decrease in the threshold concentration of nonequilibrium carriers required to begin of plasmon-phonon gain under conditions of optical excitation.

The optical phonon spectra in an HgTe quantum well surrounded by CdHgTe barriers are calculated, taking into account the contribution of free electrons to the dielectric permittivity of the quantum well. It is shown that free electrons not only change the phonon spectrum, but they can also change the number of branches of the surface optical phonons. The frequencies of the electron -optical phonon collisions, the wave -vector relaxation rates, and the energy relaxation rates are calculated for different temperatures and electron concentrations. The dependencies of the momentum and energy scattering frequencies on the electron kinetic energy are found.

The influence of the presence of free electrons on the spectra of optical phonons and on electron-optical phonon scattering in quantum wells has been theoretically studied. As an example, calculations of the optical phonon spectra, intrasubband and intersubband electron-optical phonon scattering in 10-nm-GaAs quantum wells surrounded by Al0.3Ga0.7As barriers were carried out at two temperatures of 77 and 300 K. It was shown that the frequency of intrasubband scattering varies nonmonotonically with increasing electron concentration in the quantum well. The relaxation rates of the wave vector and energy for scattering in the first and second subbands are found. It is shown that with increasing electron concentration in the quantum well, the frequency of intersubband scattering decreases.

The dielectric continuum model has been developed to describe the optical phonons in quantum well with anisotropic permittivity. The developed model is used to calculate the spectra and potentials of the optical phonons in a CdHgTe/HgTe heterostructure with narrow-gap quantum wells.

We propose an original design for a HgCdTe-based terahertz vertical-cavity surface-emitting laser with twenty 5 nm HgTe quantum wells. Feasibility of laser generation at 9 THz and a lattice temperature of 8 K is shown. The estimate of the threshold pump intensity using laser radiation at a wavelength of 5 μm is 3 W/cm2, which makes it possible to expect continuous wave (CW) mode lasing. Such a low required pump intensity will make it possible to create a very compact system of a laser pumped by CW mid-infrared quantum cascade laser.

The capture times of holes to the shallow excited levels of neutral mercury vacancy via acoustic phonon emission are calculated for Hg1 – xCdxTe, as well as the transition times of holes from shallow localized levels to the continuum of the valence band at different temperatures. Due to the redistribution of carriers in the valence band with temperature, the time of carrier capture to the localized levels of the neutral vacancy increases, and the time of reionization to the continuum decreases. Based on the calculation results, a model is proposed to describe the temperature quenching of photoluminescence caused by radiative transitions between the localized states of holes on a neutral mercury vacancy.

Amplified interband emission within the 14–24 μm range is investigated in HgCdTe-based quantum wells under optical pumping. Carrier lifetimes are shown to be marginally limited only by Shockley–Read–Hall recombination, fully realizing the advantage of relativistic energy spectra of 2D HgCdTe in terms of suppressing the Auger processes. By carefully optimizing the waveguides and mitigating carrier heating, we achieve amplification thresholds as low as 1.5–2 W/cm2 at a pulse duration of 20–500 μs. With last generation quantum cascade lasers used for optical pumping, we estimate that continuous-wave HgCdTe lasers can operate in the very long-wavelength range (15–30 μm) and beyond.

The studies of the interband electron transition energy in multiple Hg1-xCdxTe/Hg1-yCdyTe quantum wells (MQWs) at room temperature were carried out. The MQWs were grown on the (013) GaAs substrate by molecular beam epitaxy, with the layer composition and thickness being measured by the in-situ ellipsometric parameters measurement at the nanometer level. The Hg1-xCdxTe barrier composition and width were x = 0.69 and 30 nm, respectively. The Hg1-yCdyTe well composition was y = 0.06–0.10, and the width varied in the range of 2.7–13 nm. The experimental data of the interband electron transition energy were determined by the absorption spectral analysis. The calculation of the interband electron transition energy was carried out on the basis of the four-band Kane model. A good agreement between the experimental and calculated data was obtained. It was shown that MQWs may be used as a photosensitive material for creating infrared optoelectronic devices operating in different modes in the range of 3–10 μm at room temperature.

Due to their widely tunable bandgap, HgCdTe heterostructures with quantum wells are a promising material system for semiconductor lasers in the entire mid-infrared range. Recently, Auger-suppressed structures allowed interband stimulated emission (SE) in the atmospheric transparency window 3–5 μm well above 200 K, while previously it was limited to temperatures below 175 K. In contrast to earlier works focused on ridge or vertical emitting HgCdTe lasers, here we demonstrate a whispering gallery mode microdisk (d = 50 μm) laser operating under optical pumping at ∼4 μm in the temperature range attainable by the thermoelectric cooling. Above 200 K, the emission spectrum consists of multiple 0.37-meV-wide peaks associated with the modes of the disk resonator. Laser generation is achieved up to 230 K, which is 40 K lower than the quenching temperature of SE in the unprocessed macroscopic sample. We associate the difference with the optical losses introduced by the inclined walls of the disk.

A magnetic field parallel to the layers of a double quantum well with conventional semiconductor constituents leads to a relative shift of the conduction band spectra of the constituent layers along the wave vector perpendicular to the field. If the states of the layers are tunnel-coupled, a tunneling gap is formed at the intersection of the single-layer spectra and is shifted upward with increasing field. This leads to striking features in the magnetoresistance caused by intersections of the Fermi level with the edges of the tunneling gap. Similar studies of transformations of the spectrum of the double quantum well in a HgTe/CdHgTe heterosystem, which has a p-type conductivity and HgTe layers with a gapless inverse energy spectrum, are reported in this work. Our experiments and corresponding calculations in the eight-band kp approach indicate that the evolution of the magnetoresistance with the variation of the in-plane field here has a much more complex and diverse character depending qualitatively on the thickness of the layers.

A magnetic field parallel to the layers of a double quantum well with conventional semiconductor constituentsleads to a relative shift of the conduction band spectra of the constituent layers along the wave vector perpendicularto the field. If the states of the layers are tunnel-coupled, a tunneling gap is formed at the intersectionof the single-layer spectra and is shifted upward with increasing field. This leads to striking features in themagnetoresistance caused by intersections of the Fermi level with the edges of the tunneling gap. Similarstudies of transformations of the spectrum of the double quantum well in a HgTe/CdHgTe heterosystem,which has a p-type conductivity and HgTe layers with a gapless inverse energy spectrum, are reported in thiswork. Our experiments and corresponding calculations in the eight-band kp approach indicate that the evolutionof the magnetoresistance with the variation of the in-plane field here has a much more complex anddiverse character depending qualitatively on the thickness of the layers.

The energy structure of the size quantization levels in multiple Hg0.3Cd0.7Te/HgTe quantum wells grown via molecular beam epitaxy on a (013)GaAs substrate has been studied. Experimental and calculated energy positions of three size quantization levels are obtained.