Hole-hole and electron-hole exchange interactions in single InAs/GaAs quantum dots

AbstractSeveral studies to date have probed structural phase transitions in quantum dots (QDs) at high pressure. At low pressure (< 1 GPa), the optical properties of solvated nanomaterials are modulated by pressure induced electronic level tuning, particularly for surface and trap states. In fact, low pressure studies on solvated CdSe QDs may provide insight into the participation of surface hole traps and electron traps on the excited state optical properties in these materials. We report findings of QD size dependent pressure coefficients and postulate that trap state tuning, surface reconstruction events, and electron-hole exchange interactions may play a role in the low-pressure regime.

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Short-range versus long-range electron-hole exchange interactions in semiconductor quantum dots

Physical Review B ◽

10.1103/physrevb.58.r13367 ◽

1998 ◽

Vol 58 (20) ◽

pp. R13367-R13370 ◽

Cited By ~ 87

Author(s):

A. Franceschetti ◽

L. W. Wang ◽

H. Fu ◽

A. Zunger

Keyword(s):

Quantum Dots ◽

Long Range ◽

Short Range ◽

Exchange Interactions ◽

Semiconductor Quantum Dots ◽

Electron Hole

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Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176770 ◽

1990 ◽

Vol 48 (4) ◽

pp. 728-729

Author(s):

M.J. Kim ◽

L.C. Liu ◽

S.H. Risbud ◽

R.W. Carpenter

Keyword(s):

Quantum Dots ◽

Borosilicate Glass ◽

Glass Matrix ◽

Optical Switching ◽

Response Times ◽

Fast Response ◽

Processing Technique ◽

Internal Stresses ◽

Electron Hole ◽

Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

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