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Semiconductor Mesostructure Dielectrics

IP.com Disclosure Number: IPCOM000048086D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Price, PJ: AUTHOR

Abstract

An electric field, impressed in the layer plane direction of a superlattice type semiconductor crystalline structure having successive 10 to 100 lattice constant thickness layers of different semiconductor materials such as GaAs and GaAlAs, of a magnitude comparable to that required to produce hot electrons in bulk GaAs will modulate the dielectric constant of the structure and hence the conductivity in the direction perpendicular to the layer planes.

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Semiconductor Mesostructure Dielectrics

An electric field, impressed in the layer plane direction of a superlattice type semiconductor crystalline structure having successive 10 to 100 lattice constant thickness layers of different semiconductor materials such as GaAs and GaAlAs, of a magnitude comparable to that required to produce hot electrons in bulk GaAs will modulate the dielectric constant of the structure and hence the conductivity in the direction perpendicular to the layer planes.

The devices grown by molecular beam epitaxy have semiconductor materials made in which successive layers of the order 10 to 100 lattice constants thick and have different compositions, for example, layers of GaAs and (Ga, A1) As, doped to be n-type. The motion of electrons in the growth direction which is normal to the layer planes, in the GaAs layers, is quantized into energy levels (E(1), E(2)...) which correspond to states substantially localized in these layers, and are the bottoms of two dimensional bands of electrons states. In practice, in thermal equilibrium the electrons will be mostly on the lowest (E(1)) band.

For a homogeneous layer, like GaAs, the polarizability per electron in the E/1/ state, alpha/1/, is very large. It is approximately proportional to the 4th power of the layer width W, and to the effective mass for GaAs layers. In other words, alpha/1/ approx. equal to W/4/.10/5/ per cm. For W equals 100 angstroms and an electron density of n equals 10/18/ per...