The past three decades have been a period where useful current and voltage instabilities in
solids have progressed from exciting research problems to a wide variety of commercially
available devices. Materials and electronics research has led to devices such as the tunnel
(Esaki) diode transferred electron (Gunn) diode avalanche diodes real-space transfer devices
and the like. These structures have proven to be very important in the generation
amplification switching and processing of microwave signals up to frequencies exceeding 100
GHz. In this treatise we focus on a detailed theoretical understanding of devices of the kind
that can be made unstable against circuit oscillations large amplitude switching events and
in some cases internal rearrangement of the electric field or current density distribution.
The book is aimed at the semiconductor device physicist engineer and graduate student. A
knowledge of solid state physics on an elementary or introductory level is assumed. Furthermore
we have geared the book to device engineers and physicists desirous of obtaining an
understanding substantially deeper than that associated with a small signal equivalent circuit
approach. We focus on both analytical and numerical treatment of specific device problems
concerning ourselves with the mechanism that determines the constitutive relation governing the
device the boundary conditions (contact effects) and the effect of the local circuit
environment.
