Abstract
In this paper, we apply the angle-resolved optically detected magnetic resonance (ODMR) technique to study a series of strained (Cd, Mn)Te/(Cd, Mg)Te quantum wells (QWs) produced by molecular beam epitaxy. By analyzing characteristic features of ODMR angular scans, we determine the strain-induced axial-symmetry spin Hamiltonian parameter $D$ with neV precision. Furthermore, we use low-temperature optical reflectivity measurements and x-ray diffraction scans to evaluate the local strain present in the QW material. In our analysis, we take into account different thermal expansion coefficients of the GaAs substrate and CdTe buffer. The additional deformation due to the thermal expansion effects has the same magnitude as the deformation that originates from the different compositions of the samples. Based on the evaluated deformations and values of the strain-induced axial-symmetry spin Hamiltonian parameter $D$, we find the strain spin-lattice coefficient ${G}_{11}=(72.2\ifmmode\pm\else\textpm\fi{}1.9)$ neV for ${\mathrm{Mn}}^{2+}$ in CdTe and shear deformation potential $b=(\ensuremath{-}0.94\ifmmode\pm\else\textpm\fi{}0.11)$ eV for CdTe.
Highlights
One of the critical factors influencing the electronic and optoelectronic devices’ performance is local strain distribution
We apply the angle-resolved optically detected magnetic resonance (ODMR) technique to study a series of strained (Cd, Mn)Te/(Cd, Mg)Te quantum wells (QWs) produced by molecular beam epitaxy
The samples containing QWs used in this work were produced by the molecular beam epitaxy (MBE) technique
Summary
One of the critical factors influencing the electronic and optoelectronic devices’ performance is local strain distribution. The spin relaxation time—a crucial parameter for potential spintronic devices—strongly depends on spinlattice coupling and local strain distribution The latter is nontrivial in complex nanostructures composed of many different materials, e.g., in quantum wells (QW). New characterization techniques combined with new growth methods offer fresh insights into semiconductor physics and often shed new light on some previously determined material parameters This was the case of GaAs crystals widely used as substrates for complex semiconductor structures. In many cases (like multiple QWs structures), determining the spin Hamiltonian parameters describing such coupling may be done with electron paramagnetic resonance (EPR) techniques [4]. From the obtained deformation values and the corresponding strain-induced axial-symmetry spin Hamiltonian parameter D combined with the elastic constants, we calculate the spin-lattice coupling coefficient G11 for manganese in cadmium telluride. Our findings could be especially useful in all studies involving spin-related phenomena in CdTe-based MBE-grown nanostructures and devices including multiple-QWs and quantum dots [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]
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