Negative Differential Resistance and Instabilities in 2-D Semiconductors

Negative Differential Resistance and Instabilities in 2-D Semiconductors

Author: N. Balkan

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 437

ISBN-13: 1461528224

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Instabilities associated with hot electrons in semiconductors have been investigated from the beginning of transistor physics in the 194Os. The study of NDR and impact ionization in bulk material led to devices like the Gunn diode and the avalanche-photo-diode. In layered semiconductors domain formation in HEMTs can lead to excess gate leakage and to excess noise. The studies of hot electron transport parallel to the layers in heterostructures, single and multiple, have shown abundant evidence of electrical instability and there has been no shortage of suggestions concerning novel NDR mechanisms, such as real space transfer, scattering induced NDR, inter-sub band transfer, percolation effects etc. Real space transfer has been exploited in negative-resistance PETs (NERFETs) and in the charge-injection transistor (CHINT) and in light emitting logic devices, but far too little is known and understood about other NDR mechanisms with which quantum well material appears to be particularly well-endowed, for these to be similarly exploited. The aim of this book is therefore to collate what is known and what is not known about NDR instabilities, and to identify promising approaches and techniques which will increase our understanding of the origin of these instabilities which have been observed during the last decade of investigations into high-field longitudinal transport in layered semiconductors. The book covers the fundamental properties of hot carrier transport and the associated instabilities and light emission in 2-dimensional semiconductors dealing with both theory and experiment.


New Paths Towards Quantum Gravity

New Paths Towards Quantum Gravity

Author: Bernhelm Booß-Bavnbek

Publisher: Springer Science & Business Media

Published: 2010-06-04

Total Pages: 372

ISBN-13: 3642118968

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Aside from the obvious statement that it should be a theory capable of unifying general relativity and quantum field theory, not much is known about the true nature of quantum gravity. New ideas - and there are many of them for this is an exciting field of research - often diverge to a degree where it seems impossible to decide in which of the many possible direction(s) the ongoing developments should be further sustained. The division of the book in two (overlapping) parts reflects the duality between the physical vision and the mathematical construction. The former is represented by tutorial reviews on non-commutative geometry, on space-time discretization and renormalization and on gauge field path integrals. The latter one by lectures on cohomology, on stochastic geometry and on mathematical tools for the effective action in quantum gravity. The book will benefit everyone working or entering the field of quantum gravity research.