Effects of spontaneous ordering and alloy statistical fluctuations on exciton linewidth inGaxIn1−x

Yong Zhang

¹

,

A. Mascarenhas

²

,

Steve Smith

³

et al.

Abstract

We experimentally demonstrate an intrinsic statistical effect of the phenomenon of spontaneous ordering in semiconductor alloys: the reduction of alloy fluctuations as a function of the order parameter, as reflected in the exciton linewidth. A theoretical model is presented to qualitatively describe the dependence of the exciton linewidth on the order parameter.

A Raman Study Of Order-Disorder Phenomena In Zn1−xMnxGa2Se4 Compounds

“…Fig.2 shows the dependence of the spectra in the region of the first two A modes, for the AG (left) and AH samples (right), respectively. It can be seen that the A (2) mode increases with x in both series indicating that the order degree increases with the Mn content. A close look at the 180 cm -1 mode shows that it can be decomposed into two bands, a narrow and a broad one, with opposite behavior along the series.…”

“…All modes have been assigned in previous works in the spectra for MnGa 2 Se 4 . [6] We shall focus in the second A mode, A (2) with ν ≅ 180 cm -1 , that involves Se displacements within the tetragonal a-b plane. This mode is allowed in 4 I and forbidden in m I 2 4 s.g., as can be seen in fig.1 for the end compounds MnGa 2 Se 4 and ZnGa 2 Se 4 .…”

“…They are promising candidates for optoelectronic devices owing to their unusual combination of magnetic, optical and electronic properties [1]. Orderdisorder phenomena are important because they can change the energy gap and other optical and electronic properties [2]. In this work we present a Raman study of the Zn 1-x Mn x Ga 2 Se 4 system, focusing on the relation between the shape of some modes and the degree of cation order.…”

Effect of magnetic dilution in Zn1−xMnxGa2Se4 (0<x<0.5)

“…5 The degree of atomic ordering critically influences the physical properties ͑optical, electronic, magnetic,…͒ of the material. 6,7 A precise knowledge of the distribution of the cations in the crystal lattice is, therefore, of significant importance. In most DMSs the arrangement of the magnetic atoms is random.…”

Global electronic structure of semiconductor alloys through direct large-scale computations for III-V alloys GaxIn1−xP

“…The full width at half maximum for the histogram plot of Fig.1(b) is Δ cf = 8.3 meV, [19] which turn out to be similar to the excitonic linewidth Δ ex = 8 meV for this alloy measured by the excitonic emission at low temperature. [20] It is reasonable to expect there is some connection between Δ cf and Δ ex , but we will leave this aspect for a future work. We only wish to point out here that Δ cf is rather different from the most popularly considered mechanism for the excitonic linewidth in a semiconductor alloy where the width is caused by the energy variation as a result of composition fluctuation within the "exciton volume" from one area to the other.…”