xMnxTe Single Crystals Research Articles

Electrical and Thermal Conductivity of Solid Solution Sn1–xMn x Te (0 ≥ x ≥ 0.04)

Electrical and thermal properties of the Sn1–xMnxTe single crystals (0 ≥ x ≥ 0.04) with contacts of eutectic alloy 57Bi + 43Sn (in mass%) are investigated at temperatures from 77 to 300 K. Experimental results show that this alloy with specified single crystals forms ohmic contact with a sufficiently low contact resistance. The electronic thermal conductivity in some samples reaches about 50% of the total thermal conductivity, and structural defects contribute significantly to the thermal resistance of the crystals.

Electric and adhesion properties of an interface between Sn1 − x Mn x Te single crystals and Bi–Sn alloys

The adhesion and electric properties of an interface between Sn1 − xMnxTe single crystals and a 57 wt % Bi and 43 wt % Sn alloy in a temperature range of ∼77–300 K are studied. It is shown that the Bi–Sn alloy and the above single crystals form an ohmic contact that exhibits fairly high work of adhesion and strength of adhesion, along with low contact resistance. The deposition of the Bi–Sn alloy on the end faces of the crystals results in the formation of such intermediate phases as Bi2Te3 and SnTe at the interface, the doping of the near-contact region of the crystal, and the filling of vacancies in the tin sublattice in this region with diffusing atoms of the contact alloy components.

Influence of local magnetization on acceptor-bound complex state in Hg1−xMnxTe single crystals

We performed temperature-dependent magnetic measurements and infrared photoluminescence (PL) measurements in various geometries on a series of p-type Hg1–xMnxTe single crystals (0.20≤x≤0.26). Evolution of PL features was observed, and zero-field spin splitting was identified for the acceptor-bound magnetic polaron (A0BMP). The results show direct evidence for local spontaneous magnetization of the A0BMP. Comparison with the Ditel–Spałek model indicates that besides the fluctuation and collective regimes, the A0BMP exhibits a new regime at low temperatures owing to the formation of the spin-glass state in Hg1−xMnxTe. The dissociation energy of the exciton bound to the A0BMP ((A0,X)BMP) varied rapidly with temperature, and the ratio of the dissociation energy of the (A0,X)BMP to the binding energy of the A0BMP was larger than the classical value of the A0X and no longer a constant, which breaks the Haynes rule. The free exciton localization process helps enhance the local magnetization of the (A0,X)BMP by transferring energy from the carrier system to the Mn-spin system, and it may lead to a photoinduced configuration of non-interacting ferromagnetic domains or the photoinduced magnetization effect.

Chemical etching of Cd1 − x Mn x Te solid solution single crystals with iodine solutions in methanol

Chemical etching of Cd1 − xMnxTe (0.04 < x < 0.5) solid solution (ss) single crystals in I2 + CH3OH etching mixtures was studied. Concentration and kinetic curves of etching rates were plotted. As the manganese concentration of the solid solution increases, the rates of their etching by iodine-methanol etchants increase, too. The etchant compositions and chemical-dynamic polishing protocols for Cd1 − xMnxTe single crystals were optimized.

Subpicosecond Faraday effect in Cd1−xMnxTe and its application in magneto-optical sampling

We present our studies on a subpicosecond Faraday effect in diluted magnetic semiconducting Cd1−xMnxTe single crystals and its application in a magneto-optical (MO) sampling system for time-resolved detection of ultrafast current pulses. The measurements were performed at 10 K. We used the Cd0.38Mn0.62Te crystal as the active MO medium and a low-temperature-grown free-standing GaAs photoconductive switch integrated into a coplanar transmission line as the picosecond electrical pulse generator. We observed subpicosecond MO transients that correspond to the intrinsic MO low-temperature response in the Cd1−xMnxTe system with the high Mn concentration. The current sensitivity of our MO system was found to be ∼0.1mA. We have demonstrated that the MO sampling technique using the Cd0.38Mn0.62Te transducer is as fast as the standard LiTaO3, electro-optical sampling technique and allows for a complementary (magnetic-field component) characterization of electrical picosecond transients in ultrafast switching devices. Observation of the subpicosecond Faraday effect in Cd1−xMnxTe crystals makes them very attractive for ultrafast optical modulators.

Specific features of conductivity of Cd1−x ZnxTe and Cd1−x MnxTe single crystals

The electrical characteristics of p-type Cd1−xZnxTe (x=0.05) and Cd1−xMnxTe (x=0.04) single crystals with a resistivity of 103–1010 Ω cm at 300 K are studied. The conductivity and its variation with temperature are interpreted on the basis of statistics of electrons and holes in a semiconductor with deep acceptor impurities (defects), with regard to their compensation by donors. The depth of acceptor levels and the degree of their compensation are determined. The problems of attaining near intrinsic conductivity close to intrinsic are discussed.

Phase Diagram and Luminescent Properties of CdTe–MnTe Solid Solutions

The T–x phase diagram of the CdTe–MnTe system is mapped out. The CdTe–MnTe join is shown to be nonpseudobinary. The system contains an extended series of CdTe-based solid solutions (0–71.4 mol % MnTe at 1070 K). At 1070 K, α-MnTe dissolves up to 0.3 mol % CdTe. Data are presented on the composition dependences of lattice parameters for the solid solutions studied and the luminescent properties of Cd1 – x Mn x Te single crystals annealed in cadmium or tellurium vapor.

Spectroscopic, Phototropic, and Lasing Properties of Cd1−xMnxTe Single Crystals Doped With Chromium Ions

The spectroscopic properties of Cr2+ ions in Cr:Cd1−xMnxTe (CMT) crystals are studied, and the possibility of using these impurity crystals as active media and saturable absorbers of solid‐state lasers of medium IR range is demonstrated. The bands of absorption with a maximum at 1.9 μm and of luminescence with a maximum at 2.6 μm correspond to the transitions between the levels 5T2 and 5E of the tetracoordinated Cr2+ ions with more than 1·10−18‐cm2 cross sections. The pulsed and continuous lasing modes of a Cr:CMT laser are realized in the 2.6‐μm region. The Cr:CMT crystals are characterized by effective saturation of impurity absorption. The cross sections of absorption from the ground and excited states of the Cr2+ ions at λ = 2.09 μm are determined: σgsa = 1.1·10−18 cm2; σesa/σgsa < 0.1. With the use of the Cr:CMT crystals as a passive gate the regime of Q‐switching of the Cr,Tm,Ho:YAG laser emitting at λ = 2.09 μm is obtained.

Bridgman growth and properties of Hg 1− xMn xTe single crystals

A modified Bridgman method with a high temperature gradient was used to grow Hg 1− x Mn x Te single crystals from Te-rich solution. Magnetic susceptibility experiments were performed in the temperature range from 80 to 300 K. Raman scattering measurements, carried out at room temperature, revealed two peaks characteristic of the pure HgTe spectrum at 118 cm −1 and 138 cm −1 and a third weaker peak at 256 cm −1.

Excitation Spectra of Photoluminescence Bands in Cd1–xMnx Te

The excitation spectra of photoluminescence bands B (2.0 eV), C (1.2 eV), and D (1.4 to 1.6 eV) are investigated at 5 and 78 K in Cd1–xMnxTe single crystals for 0.40 ≦ x ≦ 0.70. The data for the B-band are interpreted in terms of the model of Mn2+ intra-ion d–d transitions. The disagreement of some experimental results with this model is discussed. The photoluminescence band C, in contrast to B, is excited by several different temperature-dependent processes. The models based on the common excitation mechanism for the B and C photoluminescence bands are shown to be insufficient to interpret the experimental results. [Russian Text Ignored].

Photomagnetoresistance Cd1−xMnxTe

Photoconductivity and photomagnetoresistance (PMR) measurements on Cd1−xMnxTe single crystals for x = 0.05, 0.30 and 0.50 have been carried out in the temperature range 4.2–200 K in magnetic fields up to 10 T. PMR is very large and changes from positive to negative with increasing x. Various mechanisms which could account for the observed PMR are considered. It is concluded that the magnetic field dependent recombination of photocarriers causes a significant contribution especially at low Mn-concentrations.