Editorial

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This special issue is formed from a collection of selected papers that were presented at the 8th International Symposium on Nanostructures: Physicsand Technology in 2000 (www.ioffe.rssi.ru/NANO2000/). The annualsymposia are chaired by two Nobel Prize winners, Professor Zh Alferov andProfessor L Esaki, and are traditionally organized by the IoffeInstitute in Repino - a suburb of St Petersburg. The Symposium waslaunched in 1993 by its Chairs as one of the first in an area that isbecoming one of the leading and more important directions within modernsolid state physics and technology.Perhaps it would be appropriate to recall the history of the prefix nano in the title of the Symposium. In the late 1950s, Dr JKilby at Texas Instruments and Dr R Noyce at Fairchild Semiconductor proposed the fabrication of integrated electronic circuits ongermanium and silicon crystals, and successfully realized this idea. This created, after the invention of the transistor by J Bardeen,W Brattain and W Shockley in 1947, the next great revolution in informationtechnology. The integrated circuits were formed with elements on themicrometre scale; this is why this area of science and technologybecame known as microelectronics. However, this developmentled to a decrease of the characteristic scale to a submicron level. Actually, the typical thickness of the oxide film on Si-based integratedcircuits is now about 10 nm and the gate width is a little more than 100nm.In the middle of the 1960s, a new direction in solid stateelectronics and optoelectronics was pushed forward. This direction wasbased on applications of semiconductor heterostructures. The foundationsof this area were laid by Zh Alferov and H Kroemer.Heterostructure applications make real the exploitation of quantum mechanicalbehaviour of electrons and holes in solids. The basic concepts in thisarea were given by L Keldysh (1962), L Ioganson (1963), R Davis andH Hosack (1963), L Esaki and R Tsu (1969), R Kazarinov and R Suris(1971) and R Dingle and C Henry (1974). Naturally, to providequantum mechanical behaviour and avoid carrier scattering by phonons and lattice defects, it was necessary to fabricatestructures on the nanometre scale. This had become possiblebecause of the pioneering work by A Cho on molecular beam epitaxy.Following L Esaki, the fabrication of structures and devices withquantized electrons and holes can be called `carrier wavefunctionengineering'.The development of nanoscale semiconductor heterostructuresled to the low threshold injection lasers with quantum wells and thehigh-speed transistors that revolutionized informationtransmission and storage technologies.Recently, the team headed by Zh Alferov demonstrated thepossibility of further radical improvement in semiconductorlaser performance characteristics with the use of nanostructures withquantum dots. New remarkable achievements in the mid- andfar-infrared techniques are in progress. First of all, there is a quantumcascade laser that was created by the team of F Capasso and quantumwell infrared photodetectors utilizing intrasubband electron (hole)transitions. New structures and technologies based onapplications of nanoclusters such as carbon nanotubes are underconsideration.So now the terms nanoelectronics and nanostructures are as widely in use as the terms microelectronics and microstructures.It is natural that the Symposium is traditionally organized bythe Ioffe Institute and held in St Petersburg. Here, N Goryunovaand A Regel, at the same time as H Walker, discovered the semiconductingproperties of the group III-V compounds that became the basic materials for semiconductor nanostructures. Here, thefirst `ideal' GaAlAs heterostructures and the heterostructure lasers were proposed and developed, andhere also, many of the basic concepts in semiconductorelectronics and optoelectronics were formulated. The Ioffe Institute is still pioneeringin many directions of this impetuously developing area.The 9th International Symposium on Nanostructures: Physics and Technologywill be held on 18-22 June, 2001, see www.ioffe.rssi.ru/NANO2001.