Problems in the Development of Efficient Biotechnology for the Synthesis of Valuable Components from Microalgae Biomass

Theoretical Foundations of Chemical Engineering - In recent decades, active research has been under way to find alternative sources of renewable raw materials for the production of valuable...     

Capacitive Properties of Metal–Insulator–Semiconductor Systems Based on an HgCdTe nBn Structure Grown by Molecular Beam Epitaxy

Journal of Communications Technology and Electronics - The capacitance–voltage (CV) curves of metal–insulator–semiconductor (MIS) systems based on an HgCdTe nBn structure grown by...     

Infrared focal plane assemblies based on HgCdTe/Si(310) heterostructure

It is demonstrated for the first time that high-performance scanning infrared (IR) focal plane assemblies of the 288 × 4 format for long-wavelength (8–12 μm) IR spectral range can be created based on a Cd _x Hg_{1 − x} Te/Si(310) heterostructure.     

Ion-beam-induced modification of the electrical properties of vacancy-doped mercury cadmium telluride

The effect of ion-beam milling (IBM) on the electrical properties of vacancy-doped mercury cadmium telluride (MCT) p-Hg_1−x Cd _x Te (x ∼ 0.22) has been studied. The samples were prepared by thermal annealing of molecular beam epitaxy (MBE)-grown heterostructures and the films and single crystals grown by liquid-phase epitaxy (LPE). The etching of samples by IBM resulted in the formation of donor centers. In MBE-grown heterostructures (but not in LPE-grown samples), the concentration of these centers reached ∼10¹⁷ cm⁻³. It is established that the appearance of a high concentration of donor centers in the heterostructures is caused by the IBM-induced activation of neutral defects formed during epitaxial growth. The probable nature of defects is discussed.     

Defects in heteroepitaxial CdHgTe/Si layers and their behavior under conditions of implanted p +-n photodiode structure formation

The impurity-defect structure of heteroepitaxial Cd _x Hg_{1 ? x} Te/Si (0.35 < x < 0.39) layers grown by molecular beam epitaxy for the creation of arsenic-ion-implanted p ⁺-n junctions has been studied by the photoluminescence method. It is established that full realization of the possibilities of p ⁺-on-n photodiode structures based on the CdHgTe/Si system is hindered by uncontrolled doping of the material that leads to the formation of both shallow (impurity level energy ～10 meV) and deep (～50 meV) acceptor levels.     

Defects in mercury-cadmium telluride heteroepitaxial structures grown by molecular-beam epitaxy on silicon substrates

Defects in mercury-cadmium-telluride heteroepitaxial structures (with 0.3 to 0.4 molar fraction of cadmium telluride) grown by molecular-beam epitaxy on silicon substrates are studied. The low-temperature photoluminescence method reveals that there are comparatively deep levels with energies of 50 to 60 meV and shallower levels with energies of 20 to 30 meV in the band gap. Analysis of the temperature dependence of the minority carrier lifetime demonstrates that this lifetime is controlled by energy levels with an energy of ～30 meV. The possible relationship between energy states and crystal-structure defects is discussed.     

Electrical and optical properties of CdHgTe films grown by molecular-beam epitaxy on silicon substrates

The electrical and optical properties of epitaxial CdHgTe films grown on silicon substrates by molecular-beam epitaxy have been studied. The results of photoluminescence measurements are indicative of the high structural perfection of the films, and Hall data combined with low-energy ion treatment point to a low concentration of residual donors (??5 × 10¹⁴ cm^?3). Acceptor states supposedly related to the capture of impurities at structural defects typical of strongly lattice-mismatched heteroepitaxial structures are found in the films.     

Photoluminescence of CdHgTe solid solutions subjected to low-energy ion treatment

The photoluminescence (PL) of CdHgTe solid solutions subjected to low-energy ion treatment is studied. A blue shift of the peaks in the PL spectra is observed immediately after ion treatment, which is attributed to the formation of a high concentration of donor defects and to the Burstein-Moss effect. The change in the shape of the PL spectra and, in particular, the disappearance of lines associated with transitions to acceptor states indicate that these defects are formed by the interaction of interstitial mercury atoms introduced into the sample during the course of treatment with impurity atoms. As the treatment is terminated, the electron concentration decreases due to the disintegration of defects and the blue shift disappears, but the shape of the spectra remains unchanged. This behavior of the PL spectra can be used for diagnostics of the defect-impurity structure of CdHgTe.     

Integrated analytical equipment for control of film growth in MBE technology

The integrated analytical equipment has been developed for in-situ measuring growth rate and film composition by the ultra-fast ellipsometer, surface temperature by the polarization-type pyrometer and for precise control over the epitaxial processes by automatic control system. This complex was used to control the mercury cadmium telluride heteroepitaxial structure growth on GaAs substrate with various composition distributions throughout the thickness. The maintenance accuracy of Hg_1−xCd_xTe composition during growth was up to ΔX_CdTe=±0.0005. The maintenance accuracy of substrate temperature was found to be up to ±1°C.