Mnx Te Research Articles

Variations in the structural and electrical properties as a function of depth in CdTe layers grown on InSb substrates

The electrical properties of CdTe and CdMnTe layers grown on (001) InSb substrates by MBE have been studied as a function of depth through the layers. Using capacitance-voltage profiling techniques, the free carrier concentration has been found to be significantly reduced in the vicinity of the substrate and corresponding depth-resolved DLTS measurements have revealed the presence of trapping states only in the region of reduced carrier density. For Cd 1− x Mn xTe layers, a greater reduction in carrier density is observed as the Mn concentration is increased. These observations are explained in terms of the presence of extended defects which are expected to result from the relief of strain due to lattice mismatch at the substrate-epilayer interface. This interpretation is supported by measurements and computer-aided simulations of DCXRD rocking curves which indicate a graded strain structure in these layers.

Excitons and type I – type II transition under magnetic fields

We discuss the effects of a magnetic field on CdTe Cd 1− x Mn xTe heterostructures and show that, at moderate Mn concentration, a pseudo-type I to pseudo-type II transition occurs, namely the holes become localized in the semimagnetic ternary layer. We emphasize the role of excitons and present the results of a variational calculation of their binding energy. The valence band offset obtained in a 〈111〉 grown sample is compared to other available data.

Nearest and next nearest neighbor exchange interaction between magnetic ions in II–VI semimagnetic semiconductors

The Mn-Mn exchange constants, which have been determined accurately in the last few years using various experimental methods, are analysed versus Mn composition, x, and interionic distance in II–VI semimagnetic semiconductors. The theoretical expression of the mean exchange constant, J 1, between nearest neighbor is given versus x. Theory and experimental values are in agreement in the whole composition range. The exchange interaction between next nearest neighbor, J 2, obtained from the study of the high magnetic fields magnetization versus x up to x = 0.11 for Cd 1- x Mn x Te and Zn 1- x Mn x Te are reported. Neglecting longer range interactions, the Curie-Weiss temperature, θ c, of telluride compounds is calculated from J 1 and J 2 versus Mn composition. The result of the calculation is compared to the data available in the literature. For high x, a curvature of θ c versus x which is negative for Zn 1- x Mn xTe and positive for Cd 1- x Mn x Te is observed.

Ultrafast polarization spectroscopy of diluted magnetic semiconductor superlattices

We are applying luminescence upconversion spectroscopy to the study of charge-carrier spin dynamics in magnetic semiconductor systems. Observing the luminescence from Cd 1− x Mn xTe quantum wells, we monitor with subpicosecond resolution the evolution of spin polarization in the electron-hole system and its dependences on carrier energy, magnetic field, and excitation conditions. The results give a direct view of the terahertz-rate spin scattering processes which have been estimated for these sytems.

Photoluminescence of Cd1−xMnxTe films grown by metalorganic chemical vapor deposition

Cd1−x Mnx Te (CMT) films grown by metalorganic chemical vapor deposition on GaAs, CdTe/GaAs, and CdS/SnO2 /glass (CSG) have been studied at 2 and 80 K by photoluminescence (PL). Analysis of the CMT bandedge peak yields Mn concentration x and indicates the degree of stress in the films due to lattice mismatch with the substrates, which also causes a blue shift of the PL band with temperature. A CdTe buffer layer greatly reduces stress and resulting defects. PL spectra from polycrystalline CMT films on commercial CSG wafers, reported for the first time, show a strong band near 1.62 eV which may represent states at the CMT-CdS interface. In CMT/CdTe/GaAs, we see evidence of front-to-back inhomogeneity in the CMT film which may appear in layered form.

The performance of Hg 1− xMn xTe photodiodes

The intrinsic carrier concentration and carrier lifetime in Hg 1− x Mn xTe are calculated for the temperature range 77–300 K and the compositional range 0.07 ⩽ x ⩽ 0.20. The influence of different junction current components on the R 0A product of p +− n photodiodes at 77 K is analysed. The highest observed R 0A values are determined by the generation-recombination current in the depletion layer. The comparison between results of calculations and the experimental data shows potential possibilities for constructing higher quality Hg 1− x Mn x Te photodiodes.

HgMnTe light emitting diodes and laser heterostructures

Pulsed current operated light emitting diodes (LED’s) and semiconductor laser heterostructures for the wavelength range 5.3–5.7 μm have been prepared employing dilute magnetic Hg1−x−y Cdx Mny Te and Hg1−x Mnx Te semiconductors. The influence of the excitation current, temperature, and magnetic field on the spectral characteristics of the spontaneous and stimulated emission have been studied. Diodes and lasers were fabricated through a combination of Bridgman, isothermal vapor and liquid phase epitaxy growth, substitutional doping, and annealing in a mercury saturated atmosphere. The series resistivity of the devices was reduced by using highly doped and graded composition substrates. A high optical confinement factor and low threshold current density were achieved using a double‐sided heterostructure configuration.

Growth and characterization of CdMnTe and CdZnTe polycrystalline thin films for solar cells

Thin films of Cd 1−x Zn xTe and Cd 1−x Mn xTe with x<0.5 were deposited by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) respectively. Electrical and optical properties of these films were studied in addition to the fabrication and characterization of glass/SnO 2/CdS/CdZnTe or CdMnTe/ZnTe/Au front-wall solar cells. Polycrystalline Cd 1−x Mn xTe films with x as high as 0.3 were successfully grown by the MOCVD technique. The Cd 0.95Mn 0.05Te film gave cell efficiencies in the range 6.0% – 6.7%. Polycrystalline CdZnTe films with band gaps of about 1.65 eV were successfully grown by MBE. The efficiency of CdZnTe was only about 1%, owing to the very high series resistance of the undoped films, although the spectral response of the CdZnTe cell was much better than that of the 6.2% efficient CdMnTe cells. CdZnTe films are now being doped with antimony.

Picosecond dynamics of magnetic polarons in Cd 1− xMn xTe

We report the dynamical behavior of magnetic polarons (MPs) in Cd 1− x Mn xTe ( x=0.05-0.6). Exciton Luminescence in samples of x=0.05−0.1 shows the dynamics of the acceptor-bound MP, where the formattion time of the bound MP is 1–2 ns. For x=0.2−0.4 the free MP is created and relaxes into deep localized states in the fluctuating band gap, forming the localized MP. For x⩾0.5 the lifetime of the MP decreases to less than 250 ps, which is caused by fast-energy transfer of the exciton energy to delectrons of the Mn ions. The spin-glass ordering of the Mn spins for x⩾0.2 at low temperature is found to affect the MP energies.

Spin glass freezing in Cd 1- x Mn xTe

The static and dynamic properties of Cd 0.6Mn 0.4Te have been investigated from Faraday rotation measurements. In the frequency range 0.6< v<10 5 Hz, the variation of the spin glass freezing temperature T f( v), defined by the cusp of the ac magnetic susceptibility is described by a Vogel-Fulcher law. T f becomes frequency independent for v<0.6 Hz.

Second harmonic generation in Cd 1− xMn xTe

Infrared second-harmonic generation in Cd 1− x Mn x Te has been experimentally demonstrated. The nonlinear susceptibility d 14(−2 w, w, w) referred to the known value d 14 for CdTe has been determined for Cd 1− x Mn x Te ( x⩽0. .5) from measurements of second-harmonic power using a Q-switched Co 2 laser. The values of nonlinear susceptibility are much bigger for Cd 1− x Mn xTe than for CdTe. It has been proved that Cd 1− x Mn x Te crystals can be used for high-power efficiency second-harmonic generation of laser infrared radiation.

Compensation of p-Type Cd1−x Mnx Te by Diffusion of Ag

physica status solidi (a)Volume 84, Issue 2 p. K181-K184 Short Note Compensation of p-Type Cd1−x Mnx Te by Diffusion of Ag A. J. Szadkowski, A. J. Szadkowski Institute of Physics, Polish Academy of Sciences, Warsaw Search for more papers by this authorA. Lubomirska-Wittlin, A. Lubomirska-Wittlin Institute of Physics, Polish Academy of Sciences, Warsaw Search for more papers by this author A. J. Szadkowski, A. J. Szadkowski Institute of Physics, Polish Academy of Sciences, Warsaw Search for more papers by this authorA. Lubomirska-Wittlin, A. Lubomirska-Wittlin Institute of Physics, Polish Academy of Sciences, Warsaw Search for more papers by this author First published: 16 August 1984 https://doi.org/10.1002/pssa.2210840264Citations: 1 al. Lotników 32/46, 02-668 Warsaw, Poland. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume84, Issue216 August 1984Pages K181-K184 RelatedInformation

Cd1−xMnxTe-CdTe multilayers grown by molecular beam epitaxy

Single-crystal multilayers of the dilute magnetic semiconductor Cd1−x Mnx Te (x∼0.2) alternating with CdTe have been successfully grown for the first time using the molecular beam epitaxy technique. Four sets of superlattices have been prepared consisting of 14, 60, 90, and 240 double layers of average thickness 460, 140, 75, and 37 Å, respectively. Each set consists of two samples grown simultaneously using 7×15×1-mm thick (0001) sapphire substrates onto which 5.0-μm-thick CdTe buffer layers were first deposited. X-ray diffraction techniques were employed to verify that epitaxy had been achieved and to obtain the average lattice constant of each of the multilayer structures. X-ray diffraction satellites were observed on both sides of the (111) diffraction peak of the superlattices composed of 14 and 60 alternating layers, respectively, which allowed an accurate estimate of the superlattice period, or double-layer thickness, for these samples. Results of UV reflectance studies and photoluminescence experiments at liquid nitrogen temperatures are also presented and discussed.

Measurements of g-factor and exchange integral J in Hg 1−x Mn xTe by means of tunneling

In dynamic conductivity d I/d V vs. V of tunnel junctions HgMnTe/Al 2O 3/Pb the peaks at V = 0 in low magnetic fields and the dips in higher fields are observed. These zero bias anomalies (ZBA) are interpreted in terms of interaction between tunneling electrons and magnetic moments of Mn ions. From the dependence of ZBA on magnetic field the g-factor vs. H and the exchange integral J have been deduced.

Quantitative measurements of magnetic polaron binding on acceptors in CdMnTe alloys

The acceptor binding energy is measured as a function of Temperature and composition in Cd1−x Mnx Te alloys, by time resolved spectroscopy. The Bound magnetic polaron effect is measured and compared with a theory accouting for magnetic saturation and fluctuations.

Transition from spin-glass to single impurity behavior in CdMnTe.

Abstract The magnetization of polycrystal Cd1−x Mnx Te has been measured from 2K down to 10 mK in a field of 10 0e for samples with Mn concentrations x of 5%, 1% and 0.05%. The two most concentrated samples show a broad transition from a paramagnetic to a spin glass phase. The most dilute sample does not show such transition but it shows hyperfine interaction effects characteristic of single impurities.

Magnetic properties of Cd1−x Mnx Te at low temperatures

Magnetic properties of the insulating Cd1−x Mnx Te system with 0.2 < x < 0.5 are investigated in the vicinity of the freezing temperature Tg. The linear dependence of Log Tg vs x−13 which is found, is related to an exponential decrease of the exchange integral J(Rij). We can deduce a first estimation of the ratio between nearest and next nearest neighbour exchange integrals J1/J2 ∼ 8.