Origin of The Concept of Quantum Wells
In 1972, Charles H. Henry, a physicist and newly-appointed Head of the Semiconductor Electronics Research Department at Bell Laboratories, had a keen interest in the subject of integrated optics, the fabrication of optical circuits in which the light travels in waveguides.
In late 1972, while pondering the problems associated with waveguides, he had a sudden insight, a realization that a double heterostructure is a waveguide for electron waves, not just lightwaves. On further reflection, he saw that there is a complete analogy between the confinement of light by a slab waveguide and the confinement of electrons by the potential well that is formed from the difference in bandgaps in a double heterostructure.
Henry realized that there should be discrete modes (levels) in the potential well, and a simple estimate showed that if the active layer of the heterostructure is as thin as several tens of nanometres, the electron levels would be split apart by tens of milli-electron volts, which should be observable. This structure is now called a quantum well.
Henry then calculated how this quantization would alter the optical absorption edge of the semiconductor. His conclusion was that instead of the optical absorption increasing smoothly, the absorption edge of a thin heterostructure would appear as a series of steps.
In addition to Henry's contributions, the quantum well (or double-heterostructure laser, as it was originally known) was actually first proposed in 1963 by Herber Kroemer in Proceedings of the IEEE and simultaneously (in 1963) in the U.S.S.R by Zh. I. Alferov and R.F. Kazarinov. Alferov and Kroemer shared a Nobel Prize in 2000 for their work in semiconductor heterostructures.
Read more about this topic: Quantum Well Laser
Famous quotes containing the words origin of, origin, concept, quantum and/or wells:
“Someone had literally run to earth
In an old cellar hole in a byroad
The origin of all the family there.
Thence they were sprung, so numerous a tribe
That now not all the houses left in town
Made shift to shelter them without the help
Of here and there a tent in grove and orchard.”
—Robert Frost (1874–1963)
“The origin of storms is not in clouds,
our lightning strikes when the earth rises,
spillways free authentic power:
dead John Brown’s body walking from a tunnel
to break the armored and concluded mind.”
—Muriel Rukeyser (1913–1980)
“The concept of a person is logically prior to that of an individual consciousness. The concept of a person is not to be analysed as that of an animated body or an embodied anima.”
—Sir Peter Frederick Strawson (b. 1919)
“A personality is an indefinite quantum of traits which is subject to constant flux, change, and growth from the birth of the individual in the world to his death. A character, on the other hand, is a fixed and definite quantum of traits which, though it may be interpreted with slight differences from age to age and actor to actor, is nevertheless in its essentials forever fixed.”
—Hubert C. Heffner (1901–1985)
“Yes, that’s what I needed. Living flesh from humans for my experiments. What difference did it make if a few people had to die? Their flesh taught me how to manufacture arms, legs, faces that are human. I’ll make a crippled world whole again.”
—Robert Tusker, and Michael Curtiz. Wells (Preston Foster)