EPR Spectra of Cr in CdTe Crystals

Abstract

The EPR studies of CdTe:Cr were performed on X-band (9.6 GHz) spectrometer at room temperature. Single CdTe crystals were doped by chromium Cr in the synthesis process. The spectra observed were resolved into two spectra. The first one consisted of very broad line (∆B = 100 mT) and the second one showed a typical fine structure. The complete angular dependence measurements were obtained. The fine structure of Cr 2+ or Cr 3+ions was assumed and simulated. It follows from the theoretical analysis of the obtained spectra that degree of ionization of the chromium Cr dopant is 3+.

Quantum Phase Transition from Superparamagnetic to Quantum Superparamagnetic State in Ultrasmall Cd1–xCr(II)xSe Quantum Dots?

“…The observed D-value is essentially similar to that for CdCrTe. 70 The nonzero intercept for peak 2 is indicative of a multiplet ground state (Γ 1 , Γ 2 ), while peak 3 arises from the Γ 5 SO split state, yielding a y-intercept of zero, consistent with the assignment of a singlet state. The data are consistent with the expectations for JT distortion coupled to SO contributions to the energy levels in the Cr(II) system.…”

“…From the y-intercept for peak 2 (g (2) = 2.075) the ZFS of the level can be extracted, yielding a D-value of 0.32 cm À1 . The observed D-value is essentially similar to that for CdCrTe 70. The nonzero intercept for peak 2 is indicative of a multiplet ground state (Γ 1 , Γ 2 ), while peak 3 arises from the Γ 5 SO split state, yielding a y-intercept of zero, consistent with the assignment of a singlet state.…”

Evidence of a ZnCr2Se4 Spinel Inclusion at the Core of a Cr-Doped ZnSe Quantum Dot

“…One magnetic dopant ion that has received little attention in the QD community is chromium. In Cr-doped II–VI semiconductors, the incorporation of Cr(I), , Cr(II), , and Cr(III) , have been reported by solid-state synthesis. Of the three oxidation states, the Cr(III) oxidation state is preferred due to its one-half-filled t 2g level and has been shown to be naturally introduced into octahedral ( O h ) sites formed by ion vacancies that charge compensate the lattice in the otherwise tetrahedral coordination environment observed in II–VI semiconductors (ZnS, ZnSe, CdS, CdSe) .…”

Compensation of hole conductivity in CdTe crystals doped with Cr

“…Cadmium telluride crystals doped with Cr impurity have recently attracted considerable interest as a promising material for high-performance lasers in the middle infrared range [1] and as a semimagnetic semiconductor in spintronics [2]. At the same time, there are few works devoted to the study of optical and electrophysical properties of CdTe:Cr [3][4][5][6][7], and the problem of the mechanism of the introduction of Cr impurity into the CdTe lattice remains to be solved. On the base of earlier studies [4], it was considered that the doping of CdTe with Cr does not involve the introduction of electrically active centers.…”

“…This conclusion is refuted by the results in [5], since the reliably observed semiinsulating state of CdTe-Cr crystals cannot be attributable only to the presence of uncontrolled impurities. In addition, it should be taken into account that Cr ions can be in different charge states [5,6], as well as that this impurity can form clusters in CdTe crystals [5].…”