Bennett, High Dopant and Carrier Concetration Effects in Gallium Aluminum Arsenide: Densities of States and Effective Intrinsic Carrier Concentrations, J.
Bennett, High Dopant and Carrier Concentration Effects in Gallium Aluminum Arsenide: Densities of States and Effective Intrinsic Carrier Concentrations, J.
Tolk and his co-workers studied the "conduction band discontinuity" between such pairs of semiconductors as gallium arsenide and gallium aluminum arsenide
by irradiating the interface with infrared light from the Vanderbilt free-electron laser.
Using a relatively thick layer of gallium arsenide as a crystal template, they stack alternating layers of gallium arsenide and aluminum arsenide
molecules to form two mirror-like regions.
First, directly on the substrate, the researchers lay down a roughly seven-atom-deep dissolvable film of aluminum arsenide. Next comes the thin laser assembly: A layer of semiconductive gallium arsenide underlies four more layers that alternate between less-conductive gallium aluminum arsenide and gallium arsenide.
Treatment with hydrofluoric acid, which eats through the aluminum arsenide separation layer while leaving everything else unscathed, frees the thin-layer laser from the now reusable substrate.
The California scientists build even more intricate structures, called quantum-well-wire arrays, by using molecular beam epitaxy to lay down vertically and sometimes horizontally alternating layers of gallium arsenide and less conductive materials, in this case aluminum arsenide and aluminum gallium arsenide.
In the arrays, two relatively thick layers of aluminum gallium arsenide make a sandwich out of two thinner layers, one made of gallium arsenide and another of alternating strips of aluminum arsenide and gallium arsenide.