(Ruzyllo, Online "02) The use of this machine is extremely slow, but useful in locating and confirming locations of quantum dots in photonic crystal micro-cavities. The usage of AFM also spans many fields of research.(Hennessey Interview).
As Kevin Hennessey explains, he works with epitaxlly grown Gallium Arsenide with Indium quantum dots. He takes a substrate wafer of Gallium Arsenide and in a chamber there are connected MBE heads which are controlled to emit different elements. The environment is "high vacuum" as it has low pressures and is different from the regular air, allowing control of the emitted elements. Heat sources in the MBE heads at high temperatures of about 800-900 degrees Celsius, the atoms are "boiled off" and are emitted. Kevin detailed that when you control emitting and can let out less than a single row of atoms, then quantum dots can be formed. In this case indium tends to organize itself into the quantum dots. Through the use of MBE, you can also grow out quantum wells which operate slightly differently than quantum dots. (Hennessey Interview).
Quantum dots are small structures that confine electrons is all dimensions, and quantum wells confine electrons in only one dimension. All LED's use quantum wells, and in the future quantum dot LEDs will be used. According to Kevin, quantum level devices hold power to revolutionize all electronic nano-technology. (Hennessey Interview).
In Kevin's work he deals with a photonic crystal micro cavity. His device is made by a fabrication process. The process has accompanying pictures but does not include the appearance of quantum dots in the process, but I am going to draw them in. In The Fabrication Process Flow diagram's figure 1), we see the starting material and the composition of each layer. In figure 2) and 3), through the use of electron beam lithography, we create holes in the top substrate which are etched into the silicon nitride.
