Physics and Growth of Semiconductor Nanostructures

Haeyeon Yang
Physics Department
Utah State University

The advantages of using discrete, confined quantum states in a semiconductor heterostructure have realized better devices such as quantum well lasers and detectors. The discrete quantum states are due to nanoscale confinement of carriers inside the quantum well. After the success of quantum well devices, efforts has been made to develop devices based on further confinements, e.g. the quantum wires and dots. Very recently the growth technique using strained layers, Stranski-Krastanow (S-K) growth, has shown promise for the fabrication of such devices. In this S-K growth, a roughening occurs when the strain energy exceeds the energy cost forming additional surface area. Although the futher confinement from quantum well is quantum wires, coherent quantum dots with narrow size distribution have been realized first using S-K growth technique. Quantum wire growth, meanwhile, has been realized with substrate with high step density and pre-patterned substrates. For the first time, we have produced InAs quantum wires directly on a smooth InP surface using S-K growth mode. In this talk, the physics of higher confinements including the optical properties as well as the physics of the morphological shape transition of the nanostructures, which results in either quantum wires or quantum dots, will be discussed.