The past decades have witnessed a breathtaking progress in semiconductor device fabrication techniques, with a relentless trend towards miniaturization. Nowadays, semiconductor nanostructures of almost any desired design can be grown with a precision down to a single atomic layer by using epitaxial methods. To confine, manipulate, and control the charge and spin carriers in semiconductor nanostructures, one can vary the material or alloy composition of a sample along the growth direction, which gives rise to quantum wells or superlattices with sharp interfaces. Gradual changes of alloy composition are also possible, for example to grow parabolic quantum wells. Free electrons or holes are supplied by remote or modulation doping (the doping centers are physically separated from the wells), which leads to systems with very high mobilities. Finally, the sample is gated, and static electric fields can be applied. The above methods provide the toolbox used for “band engineering.” An easy-to-read introduction to band engineering from a historic perspective is given in the Nobel Lecture by Herbert Kroemer [Kroemer 2001]. Out of the vast number of textbooks and monographs on semiconductor nanostructures, the book by Davies is particularly recommended [Davies 1998].
KeywordsCollective Excitation Semiconductor Nanostructures Intersubband Transition Conduction Band State Parabolic Quantum
Unable to display preview. Download preview PDF.