Quantum well structures
AssigneeBritish Telecommunications plc
InventorMichael G. Burt
Life of this patent
Estimating the term…
Abstract
By forming quantum well (QW) structures with two different heterojunctions having different band offsets it is possible to form QWs having, when subjected to optical excitation, dipoles. The presence of a dipole in a narrow enough well results in QWs having absorption edges which, unlike those of conventional QWs can be shifted to the blue by application of an electric field of appropriate polarity.
Claims32
A quantum well structure comprising:
- first and second electrodes for application of an electric field normal to layers of the well,
- a quantum confinement region being formed without regions of graded compositional change,
- and having a conduction band profile tending to push electrons in the region to one side of the region and a valence band profile tending to push the holes in the region towards the opposite side of the region, and wherein electron-hole pairs with a dipole moment are produced by optical excitation of the structure.
A quantum well structure comprising:
- first and second electrodes for application of an electric field normal to layers of the well,
- a quantum confinement region including a heterostructure of two distinct regions having different compositions, and
- wherein electron-hole pairs with a dipole moment are produced by optical excitation of the quantum well structure.
A quantum well structure comprising:
- first and second electrodes for application of an electric field normal to layers of the well,
- the quantum well structure includes a quantum confinement region comprised of a heterostructure so that electron-hole pairs produced by optical excitation of the quantum well structure are produced with a dipole moment of not less than 5 Angstroms.
A quantum well structure, comprising:
- first and second barrier layers defining therebetween a quantum confinement region, the quantum confinement region comprising adjacent said first barrier layer a first material region, and
- adjacent said second barrier layer a second material region, said first and second material regions abutting each other, and
- each said material region having an essentially uniform composition throughout its thickness, the conduction band minimum in said first material region being at a lower energy than that in said second material region and the valence band maximum being at a higher energy in said first material region than in said second,
- the thickness of said first and second material regions and their composition being such that the probability density distribution of electrons in the conduction band of said quantum confinement region is skewed towards said first barrier layer, and the probability density distribution of holes in the valence band of said quantum confinement region is skewed towards said first barrier layer so that optical excitation of the confinement region produces electron-hole pairs having a dipole moment.
A quantum well structure as in claim comprising gallium antimonide and indium arsenide and aluminum antimonide, or alloys thereof.
Dependencies are inferred from the claim text.