The Gunn effect

The research that led up to the discovery of the Gunn effect is described by the author. A brief explanation of the effect is given, and the present use of Gunn diodes is also indicated     

Gunn effect bibliography

In view of the rapidly expanding interest and activity in the area of the Gunn effect, the following bibliography has been compiled for people who are studying or doing research in this area. The term "Gunn effect" is used, in general, to collectively describe a number of classes of bulk negative resistance behavior in semiconductors with energy band structures like that of GaAs. These modes of behavior include small-signal amplification, pure accumulation of space charge, mature dipole (true Gunn effect) mode. quenched accumulation (LSA) mode, and quenched dipole mode. These references deal with the theory, experimental results, and applications of the Gunn effect. Works of a fundamental nature concerning phenomena that are basic to all semiconductor behavior and other bulk negative resistance effects have not been included. Also, basic papers dealing with electron transport phenomena, such as hot electron theory and intervalley scattering, which are essential to a complete understanding of the Gunn effect and articles on the properties and band structure of GaAs, InP, CdTe, and other III-V compounds have not generally been included, although in certain cases they are listed if they have been frequently cited. As in the compilation of any bibliography, it is self-evident that some valuable and pertinent articles may have been overlooked.     

Gunn effect in MESFET-like structures

The performance of planar field-effect controlled transferred electron oscillators with different combinations of layer thickness and doping concentration has been investigated. A negative differential resistance has even been obtained with 0.29 mu m thick 1.6*10/sup 17/ cm/sup -3/ n-doped samples. This is the first time a MESFET-like active layer has exhibited the Gunn effect and has successfully been operated as a TEO at 36 GHz.<>     

YIG-tuned Gunn effect oscillator

A mechanical cavity of coaxial or waveguide type is generally used as a resonator of a Gunn oscillator. Reported here is the use of a resonator consisting of a ferrimagnetic sample instead of the mechanical cavity to obtain the electrically tunable Gun oscillator. The coupling between the Gunn diode and the the ferrimagnetic resonator was experimentally observed and oscillation frequency from 3.2 GHz to 2.4 GHz was obtained proportionally to the applied dc magnetic field.     

Gunn effect bibliography supplement

This list of references has been prepared as a supplement to our "Gunn Effect Bibliography," which appeared in this Transactions, vol. ED-15, pp. 777-788, October 1968. These references represent 1968 articles that have been published since the original bibliography was submitted, as well as additional earlier articles.     

The Gunn effect in polar semiconductors

The main features of the Gunn effect can be accounted for by the transferred electron model of Ridley and Watkins, which predicts a bulk differential negative resistance and subsequent domain formation if electrons can be transferred sufficiently rapidly from the lowest conduction-band minimum to lower-mobility subsidiary minima. Experimental results forn-GaAs in verification of such a bulk negative resistance are presented. In the longer samples the current-time waveform consists of sharp spikes separated by flat valleys, as expected from the motion of domains. The voltage across the domains is found to scale with sample length as predicted; the value of the electric field inside the domain is estimated to be ≥60 000 V/cm, while the field outside is about 1500 V/cm. Gunn effect oscillations have also been observed inn-CdTe, but not inn-InSb orn-InAs. The absence of an instability in InSb and InAs is consistent with the transferred electron model, since the subsidiary minima in these materials are believed to be too high in energy to be populated before carrier multiplication occurs. Finally, it will be shown that unless the separation of the conduction-band minima is very small, the critical electric field at which the Gunn effect occurs is reasonably well predicted by the one-band polar optical mode runaway field.     

Carrier generation-recombination in the Gunn effect

It is conventional to assume that the Gunn Instability develops on a time scale fast compared with the carrier generation-recombination processes. This enables one to account for the motion of Gunn Domains by means of a phenomenological model in which the impurity ionization remains at its thermal equilibrium value. The standard Gunn Effect model has been modified to include the space-time dependent impurity ionization expected if the carrier generation-recombination processes become important.A dispersion relation describing the linear response of the system to small perturbations for the case of field dependent recombination has been derived and used to deduce a simple stability criterion. The time evolution of the electric field when this condition is violated has been studied via a numerical solution of the phenomenological equations. Under appropriate conditions both fast and slow moving instabilities have been found to occur.     

Domain stability in the Gunn effect

The present theoretical and experimental knowledge of the high-field domain in the Gunn effect gives conflicting result. The letter shows that these can be reconciled by a modification to the published reasoning about domain formation.     

Gunn effect swept frequency oscillator

An X-band swept frequency oscillator using a Gunn diode and a ferrite phase shifter is described. Sweep widths of 800 MHz and sweep rates up to 400 Hz with less than 3 dB power variation have been obtained.     

Ferrimagnetically tunable Gunn effect oscillator

A very wide frequency tuning (5.8 to 13.0 GHz) of the Gunn effect oscillator is described, in which the properties of the ferrimagnetic resonator sphere are used as a tuning element. The circuit employed to accomplish this tuning, the power profile, and the tuning curve are also presented.     

Gunn effect with two samples in parallel

The current waveform of two long Gunn oscillators in parallel in a transmission line is described and is extended to include the effect of putting a resistor in series.     

Gallium arsenide on sapphire Gunn effect devices

The epitaxial growth of single-crystal GaAs on an insulating sapphire substrate, recently reported, has been used in the fabrication of Gunn effect devices.     

Nonuniform motion of high-field domains in the Gunn effect

In recent publications, rules have been established for obtaining the properties of the high-field domain traversing in a steady state across Gunn diodes. This letter shows that these steady-state properties cannot be reconciled with the formation stage of the domain without some extension of the theory to include the non-steady-state domain. This letter provides the necessary extension of these rules and concludes with a qualitative account of the domain dynamics from the formation stage up to equilibrium.     

The Gunn effect under imperfect cathode boundary conditions

The usual assumption in the theory of the Gunn effect of a well-behaved cathode is replaced by a more general set of boundary conditions adapted to the treatment of cathode contacts with some interface resistance. The treatment is in terms of a "control characteristic": that is, the current-field characteristic of the cathode interface itself. For contacts with an interface resistance, the control characteristic lies at least partially below the bulk current-field characteristic. This leads to the primary nucleation of depletion rather than accumulation layers. Depending on the detailed shape of the control characteristic and the location of its crossover point (if any) with the bulk characteristic, a large variety of device behavior can be explained. Examples are Gunn's preoscillation cathode fall, Kennedy's prethreshold amplification behavior, the occurrence of excessive threshold fields for the onset of oscillations, and oscillations with lower amplitude and higher frequency than for well-behaved transit time oscillations, despite good doping homogeneity.     

Possible travelling-wave parametric amplifier using the Gunn effect

It is possible to consider the Gunn-effect domain as the boundary conductor of a microstrip transmission line. It is shown that these domains may be used to vary periodically the impedance of the transmission line, and that these variations may pump a travelling-wave parametric amplifier.     

Theoretical model of magnetic effect on Gunn diode

A simplified theoretical model to explain a magnetic effect on a Gunn diode is presented. When a dc magnetic field is applied transversely to a Gunn diode, the oscillation frequency decreases. This phenomenon is explained using a concept of successive collisions of drift electrons with lattice with constant free path.     

Characteristics of Gunn effect device on bulk n-InP

Oscillation characteristics of InP Gunn diodes were studied in a resistive circuit under pulse bias operation. Peak to valley ratio of oscillation current was observed to reach 2.85 at room temperature in planar-type diodes and it stayed constant for a change in ambient temperature from 300 to 450 K. Outside field of a matured domain was found to fall to about 3 kV/cm, which is less than one third of the threshold field.