Polarized luminescence in CdS/ZnSe quantum-well structures

Schmidt, M.; Grün, M.; Petillon, S.; Kurtz, E.; Klingshirn, C.

doi:10.1063/1.126885

Cited by 33 publications

(11 citation statements)

References 6 publications

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“…It is obvious that the lower and the upper interfaces of the quantum well are not equivalent with respect to the bond directions. Their contributions to the anisotropy cannot compensate each other [10]. Therefore, the in-plane anisotropy inherently exists in the CdSe/ZnTe MQWs studied here.…”

Section: Resultsmentioning

confidence: 93%

Giant polarized optical properties in type‐II ZnTe/CdSe multiple quantum wells induced by interface chemical bonds

Chen

et al. 2004

Physica Status Solidi (b)

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PACS 72.80. Ey, 78.55.Et Photoluminescence (PL) and photoconductivity (PC) spectra were studied in type-II ZnTe/CdSe multiple quantum wells. It was found that the PL spectrum exhibits a strong in-plane polarization with respect to 〈011〉 axis with polarization degree up to 30%. The degree of polarization does not depend on the excitation intensity and temperature, which excludes extrinsic mechanisms related to the observed in-plane anisotropy. The underlying mechanism of the observed polarization dependence of the optical properties was attributed to the inherent property of the orientation of chemical bonds in ZnTe/CdSe heterostructures with no common atom. In addition, the PC spectra also display a strong polarization dependence. We therefore point out that polarized PL and PC spectroscopies provide a unique way to probe the effects of the orientation of interface chemical bonds on semiconductor heterostructures. . Even though they may make it difficult to understand the physical properties of a solid, many interesting phenomena arise from the effects of anisotropy. To have a heterostructure, we need to deposit two different materials together. It therefore breaks the chemical bonds symmetry and creates new anisotriopic properties. Semiconductor heterostructures, in AB/CD-type combination, whose two constituents do not share a common atom, are excellent candidates to search for anisotropic effects. Indeed, the quantum structures without a common atom have nonequivalent normal and inverted interfaces, which can cause in-plane anisotropy not found in a quantum structure with equivalent interface [2]. It is known that semiconductor heterostructures without a common anion or cation often show a type-II band alignment and large band offset in the conduction and valence bands. The indirect transition due to spatially separated electrons and holes therefore is restricted to a very narrow region containing the interface, and the emitted radiation will exhibit the anisotropic characteristic of the interface chemical bonds [3,4]. In this paper, we report the interface-induced in-plane anisotropy in a new semiconductor heterostructure without common atom, i.e., ZnTe/CdSe multiple quantum wells. The degree of polarization in the photoluminescence(PL) spectra as large as 30% has been observed. Through the study of the temperature and pumping intensity dependences of the polarized PL spectra, we demonstrate that the observed polarization is an intrinsic property of the ZnTe/CdSe heterostructure. In addition, we discover that the photoconductivity (PC) spectra are also very sensitive to the polarization of the incident radiation. Unlike the PL spectra, the polarization of the PC spectra can be induced by interface defects, and it covers a wide range of wavelengths. We therefore point out that polarized PC measurement is a very powerful technique to probe anisotropic defects.

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Section: Resultsmentioning

confidence: 93%

Giant polarized optical properties in type‐II ZnTe/CdSe multiple quantum wells induced by interface chemical bonds

Chen

et al. 2004

Physica Status Solidi (b)

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“…Some of them can result in a strong in-plane optical anisotropy. 9 In the case of equivalent interface combinations, such as Te-Zn•••Zn-Te or Be-Se•••Se-Be, chemical bonds at opposite interfaces of quantum wells ͑QW's͒ lie in mutually orthogonal planes (11 0) and ͑110͒. As a result, interface contributions to the lateral anisotropy cancel each other.…”

Section: Introductionmentioning

confidence: 97%

Electric-field effects on the radiative recombination in type-II ZnSe/BeTe heterostructures with equivalent and nonequivalent interfaces

et al. 2002

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Electron-hole recombination at the interfaces formed by Zn-Te and Be-Se chemical bonds has been investigated in type-II ZnSe/BeTe heterostructures at low and high levels of excitation power by means of polarized light spectroscopy with applying of electric field across the structure. A more than fourfold variation of the matrix element squared has been reached by changing the electric field for the spatially indirect optical transitions at the interface. The radiative time of electron-hole transitions at the Se-Be interface is found to be at least 50 times longer than that at the Zn-Te interface. The contribution of Be-Se interface emission in the structures with nonequivalent (Te-Zn•••Se-Be) interfaces is negligible in the whole range of applied fields. The emission at the Te-Zn interface is carefully investigated. The ratio of matrix-elements squared along and perpendicular to the Zn-Te bonds has been found to be nearly constant in the range of carrier density 10 11 /2ϫ10 12 cm Ϫ2 and equal to 7:1.

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“…Experiments on absorption-edge photoluminescence of InAs/AlSb, 1,2 ZnSe/BeTe, [3][4][5] CdS/ZnSe, 6 CdSe/BeTe, 7 and ZnTe/CdSe (Ref. 8) multilayered structures have revealed a giant in-plane optical anisotropy in type-II zinc blende lattice nanostructures grown along the [001] crystallographic direction, namely, nonequivalence between the axes x ʈ ͓110͔ and y ʈ ͓110͔.…”

Section: Introductionmentioning

confidence: 99%

Lateral optical anisotropy of type-II interfaces in the tight-binding approach

Ivchenko

Nestoklon

2004

Phys. Rev. B

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We have developed a tight-binding theory to study electronic and optical properties of type-II heterostructures CA/CЈAЈ grown from the zinc blende semiconductors CA and CЈAЈ along the crystallographic direction [001]. The sp 3 s * nearest-neighbor tight-binding model with allowance for the spin-orbit interaction is used to calculate the energy states and the in-plane linear polarization of the spatially indirect band-edge photoluminescence of InAs/AlSb and ZnSe/BeTe multilayered structures. The interface parameters for a pair of the nonstandard planes C-AЈ or CЈ-A are considered as fitting variables. A wide range of these parameters are shown to allow Tamm-like hole states localized at the interfaces. The theory leads to giant values of the light polarization in both type-II heterosystems in agreement with existing experimental findings.

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Polarized luminescence in CdS/ZnSe quantum-well structures

Cited by 33 publications

References 6 publications

Giant polarized optical properties in type‐II ZnTe/CdSe multiple quantum wells induced by interface chemical bonds

Giant polarized optical properties in type‐II ZnTe/CdSe multiple quantum wells induced by interface chemical bonds

Electric-field effects on the radiative recombination in type-II ZnSe/BeTe heterostructures with equivalent and nonequivalent interfaces

Lateral optical anisotropy of type-II interfaces in the tight-binding approach

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