Excitons in semiconducting superlattices, quantum wells, and ternary alloys

Technical Report · Thu Aug 15 04:00:00 EDT 1991

OSTI ID:5122047

Sturge, M D ^[1]; Nahory, R E; Tamargo, M C ^[2]

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1. Dartmouth Coll., Hanover, NH (United States)
2. Bellcore, Red Bank, NJ (United States)

It is now possible to fabricate semiconducting layered structures with precisely defined layer thicknesses down to one monolayer (two atomic diameters). An example is the superlattice'' (SL) structure, in which two semiconductors with different band gaps are interleaved. The electronic properties of the SL are quite different from those of the constitutents and offer interesting new possibilities both in device design and in basic physics. This proposal aims to improve our understanding of optically excited states ( excitons'' and electron-hole plasmas'') in a particular class of these structures: the so-called Type 2 indirect'' SL's in which the electron and hole created by optical excitation are separated both in real and in momoentum space. Time-resolved tunable laser spectroscopy, with and without external perturbations such as magnetic field, electric field, and uniaxial stress, are used principally to study the following phenomena. 1. Exciton states in SLs with only a few atomic layers per period, for which the familiar effective mass model'' of semiconductor states breaks down. 2. The electron-hole plasma which forms when the excitation density is high. This plasma may be in a liquid state at low temperatures. In the short period superlattices are our primary concern, electrons and holes are spatially separated, leading to internal electric fields which might be expected to have a pronounced effect on the plasma properties.

• Research Organization: Dartmouth Coll., Hanover, NH (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-87ER45330
• OSTI ID: 5122047
• Report Number(s): DOE/ER/45330-4; ON: DE91018805
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360603* -- Materials-- Properties
ARSENIC COMPOUNDS
ARSENIDES
CRYSTAL STRUCTURE
DOCUMENT TYPES
ENERGY LEVELS
EXCITED STATES
EXCITONS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
MATERIALS
MICROSTRUCTURE
PNICTIDES
PROGRESS REPORT
QUASI PARTICLES
SEMICONDUCTOR MATERIALS
SUPERLATTICES