Temperature dependence of the band-edge photoluminescence of Zn_1 xMn_xSe films

Abstract

We report a systematic investigation of band-edge photoluminescence of the diluted magnetic semiconductor alloy Zn 1−x Mn x Se for a series of compositions (0 < x < 0.485). The specimens investigated were in the form of thin films fabricated by molecular beam epitaxy. The near band-edge emissions of donor-bound excitons (designated as I 2 ) and of neutral acceptor-bound excitons (I 1 ) were systematically investigated as a function of temperature and of alloy composition. These measurements also allowed us to determine the LO-phonon energy hω LO = 31.2 ± 0.2 meV. From the temperature dependence of the bound exciton peak, the Varshni temperature parameter α was found to increase linearly with increasing Mn concentration x, while β decreased with x. From the temperature dependence of the full width at half maximum (FWHM) of the I 2 emission line, the broadening factors (T ) were determined from the fit to the data. For x > 0.20 the effect of inhomogeneous broadening inh on (T ) was found to be stronger than that of the longitudinal optical phonon term LO . Furthermore, the activation energies of thermal quenching were obtained for both the I 2 and the I 1 peaks from the temperature dependence of the bound exciton peaks, and were found to decrease with increasing Mn concentration. Finally, we show that at high temperature the broadening of the FWHM is dominated by the LO-phonon interaction.

Antiferromagnetic interaction in coupled CdSe/ZnMnSe quantum dot structures

“…The ZnSe and DMS layers both emit at 2.79 eV at 0 T, as expected for the Mn content used. 20 In the presence of an external magnetic field, the DMS PL peak undergoes a large red shift in energy by $35 meV at 5 T. This is due to the giant Zeeman splitting of the bright excitonic states of the DMS into two components, leaving the r þ active jÀ1/2, þ 3/2i state at the lower energy. Here, jm Fig.…”

A comprehensive study of temperature-dependent reflectance and photoluminescence of Zn1−xMnxO thin films grown on c-Al2O3

“…It is attributed to more amount of impurity complexes, involving lattice vacancies, stacking faults, and other kinds of crystal defects, incorporated in the thin films which have higher Mn composition fractions and accordingly larger lattice mismatch with the Al 2 O 3 substrate. It is also noticed that ⌫ LO increases with increasing Mn composition fraction as a result of the increase in the polarity of the ZnMnO films, 24 while ប LO keeps nearly constant. Figure 5͑a͒ shows the temperature-dependent PL spectra of sample A in the temperature range from 10 to 300 K. Consider the PL spectrum at 10 K. The strongest emission peak at 3.351 eV is attributed to the donor-bound exciton ͑D 0 X1͒.…”

Preparation of ternary metal chalcogenide (M1-FexS, M = Cd and Zn) nanocrystallites using single source precursors

“…DMSs are IIeVI, IVeVI or IIIeV compounds in which fraction of nonmagnetic cations has been substituted by magnetic transition metal or rare-earth metal ions, e.g., Fe 2þ in CdS to form Cd 1Àx Fe x S. In these materials, the large sp-d exchange interaction between magnetic ions and electrons in valence band [2e4] can lead to a number of unusual electronic, optical and magneto-optical properties including the ability to magnetically tune the band gap. These properties make DMSs promising candidates for fabricating magneto optical devices such as magnetic field sensors, isolators and magneto optical switches [5]. Because DMSs have interesting magnetic properties and can be easily integrated into microelectronic devices, they are considered to be one of the most promising candidate materials for spintronics [6e8] which involve manipulation of spin degrees of freedom rather than electric charge in a solid state system [9].…”