Comparative Analysis of the Electroluminescence Efficiency in Type-I and Type-II Heterostructures Based on III–V Narrow-Gap Compounds

Semiconductors - We study in detail the mechanisms of radiative and Auger recombination in type-I and type-II heterostructures based on III–V narrow-gap materials. The presence of a...     

Effect of intraband carrier relaxation on the threshold characteristics of quantum well lasers

The effect of intraband carrier relaxation on the threshold characteristics of InGaAsP quantum well (QW) lasers is studied. The dependence of the intraband hole-hole relaxation time τ _int on temperature and carrier density is analyzed. It is shown that taking into account the finiteness of τ _int and its dependence on temperature and carrier density strongly affects the gain and the threshold current density of QW lasers.     

Modification of Hg<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript>x</Subscript>Te properties by low-energy ions

We present an overview concerning the modification of properties of HgCdTe solid solutions and related Hg-containing materials under surface treatment with low-energy (60–2000 eV) ion beams. The conditions for conductivity-type conversion in p-material, dose, and time dependences of the depth of the conversion layer are analyzed. The modification of electrical properties of n-type material subjected to ion-beam treatment is discussed. The suggested mechanisms of conductivity-type conversion under low-energy ion treatment of HgCdTe doped with vacancies or acceptor impurities are regarded. Properties of p-n junctions produced by this technique are reviewed, and electrical and photoelectric parameters of HgCdTe IR photodetectors fabricated by low-energy ion treatment are analyzed. Several examples of novel device structures developed with the use of the method are presented.     

Blue-shift in photoluminescence of ion-milled HgCdTe films and relaxation of defects induced by the milling

Simultaneous measurements of electrical conductivity, the Hall coefficient, and photoluminescence (PL) spectra of ion-milled Hg_1 − xCd_xTe films (x ∼ 0.30 and 0.38) were performed during post-milling ageing of the films at 293 K. In the course of the PL study, a ‘relaxation’ of the blue-shift of the PL band of ion-milled Hg_0.70Cd_0.30Te was observed. The relaxation was caused by the decrease of the electron concentration due to gradual disintegration of defects induced by the milling. It is shown that while ion milling substantially changes the electrical properties of Hg_1 - xCd_xTe, its PL spectrum in the long-term is affected insignificantly.     

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.     

Defect structure of Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Hg<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Te films grown by liquid-phase epitaxy,studied by means of low-energy ion treatment

Treatment with low-energy ions and measurements of electrical parameters of samples have been used to study the defect structure of Cd _x Hg_{1 − x} Te films grown by liquid-phase epitaxy. The films contain neutral defects supposedly associated with tellurium nanoinclusions. Ion treatment electrically activates these defects, with a high concentration of donor centers (∼10¹⁷ cm⁻³) created in the films. These defects decompose in ∼10³ min of aging at room temperature. Then the properties of the material are determined by the concentration of residual donors, which is found to be very low (down to ∼10¹⁴ cm⁻³) for the films under study.     

Photoelectric properties of porous GaN/SiC heterostructures

The origin of photoconductivity in porous structures formed by anodization of GaN/SiC heterostructures has been studied. It is shown by comparing the photoelectric, optical, electrical, and structural properties of untreated and anodized heterostructures that this effect is due to the presence of charged states at the interface between GaN and SiC that are specific to the anodization conditions.     

Carrier Lifetime in Semiconductors with Band-Gap Widths Close to the Spin-Orbit Splitting Energies

Semiconductors - Expressions for the Auger- and radiative-recombination rates are derived in terms of Kane’s model for materials with a band-gap width close to the spin-orbit splitting...     

Parameters of Lateral and Unsteady Cord Currents in a Cylindrical Chalcogenide Glassy Semiconductor

Semiconductors - The heat-conduction equation describing the current cord in a semiconductor is approximately solved for a Ge–Sb–Te semiconductor system of cylindrical configuration. It...