The Influence of Compositional Disorder on Electrical and Optical Properties of ZnS_xSe_1−x Single Crystals

Abstract

R. 3lac11 (a), P. FLOGEL (a), L. G. SW.LINA (b), A. G. ARESHEIN (b), J. ~IAEGE: (a), and G. VOIGT (a)The influence of compositional disorder in mixed crystals on the electrical and luminescence properties of ZnS,Sel -z single crystals grown by iodine transport are investigated by measuring the spectral distribution of photoluminescence, the excitonic reflection spectra, and the temperature dependence of free-carrier concentration and mobility. Obviously there are effects describabIe in a virtual crystal approximation (VCA) as the dependence upon composition z of donor (iodine) depth and a net shift of the self-activated (SA) luminescence. BeyondVCA the fluctuations of composition result in a broadening of excitonic spectra as expected for extended wave functions or resolvable spectral shifts (subbands) of the SA luminescence as expected for highly localized states, corresponding to the well-defined varieties of nearest-neighbour compositional configurations. There are indications that the abundances of the latter are not statistical.Durch Nessungen der Spektralverteilung der , Phot,olumineszenz, der exzitonischen Reflexionsspektren und der Temperaturabhgngigkeit von freier Ladungstrtigerkonzentration und Beweglichkeit an od-dot.ierten ZnS,Sel -,-Einkristallen werden Aussagen iiber den EinfluS kompositioneller Unbrdnung in Nischkristallen auf die elektrischen und optischen Eigenschaften erhalten. Offensichtlich gibt es Effekte, die im Rahmen der virtuellen Kristallapproximation (VCA) beschreibbar sin& wie z. B. die Abhangigkeit der Donatortiefe von der Zusammensetzung r und eine Nettoverschiebung der selbstaktivierten (SA) Lumineszenz. Jenseits der VCA geben die Fluktuationen der Zusammensetzung AnlilB zu einer Verbreiterung der exzitonischen Spektren, wie fur ausgedehnte Wellenfunktionen erwartet, oder auflosbare spektrale Verschiebungen (Teilbanden) der S-4-Lumineszenz, wie fur hochlokalisierte Zustiinde erwartet, entsprechend den wohldefinierten moglichen L4nordnungen der nZchsten Nachbarn. Es werden Hinweise dafur gefiinden, daB diese Anordnungen nicht statistisch hiiufig sind.

Fluctuation‐induced broadening of exciton reflection spectra in AII BVI solid solutions

“…The experimental data on the concentration dependence of the A n = 1 ground exciton line broadening A for the Zn,Cdl-,S and Zn,Cdl-,Te systems have been taken from [4,5] and for ZnS,Sel-, from [6].…”

Effect of heat treatment and Si ion irradiation on ZnSxSe1−x single crystals grown by CVT method

“…It may arise from the Zn vacancy with a donar like I. An SA may be a Zn vacancy surrounded by three S and one I atom (V Zn S 3 I) or it may be two S, one Se and one I (V Zn S 2 SeI) or two Se, one S and one I (V Zn SSe 2 I) or three Se and one I (V Zn Se 3 I) [12]. The irradiated samples show peaks corresponding to SA emission and also an extra peak at 413 nm.…”

DC Conductivity and Dielectric Behaviour of Glassy Se<sub>100–x</sub>Zn<sub>x</sub> Alloy

“…-3 -1 -1 lo range of localized state in the glassy system. Therefore, the possibility of localized conduction in the band tails most likely present [15] in the system Se 100-x Zn x . The activation energy increases with the corresponding DC conductivity decreases due to Se-Zn has blend structure both in bulk and in thin film form [15,16].…”

“…Therefore, the possibility of localized conduction in the band tails most likely present [15] in the system Se 100-x Zn x . The activation energy increases with the corresponding DC conductivity decreases due to Se-Zn has blend structure both in bulk and in thin film form [15,16]. Selenium (Se) has about 40% atoms in a ring structure and 60% atoms are bonded polymeric chains with the conduction of p-type by J. Schottmiller [17].…”