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Easily Controllable Semiconductor Active Elements

#G-1010


General Consideration of Transverse Runaway and Transverse Breakdown and New Easily Controllable Active Elements with Versatile Functions Based Thereon and on the Nonlinear Oscillations under Hopping Conductivity Conditions in the Magnetic Field

Tech Area / Field

  • INF-ELE/Microelectronics and Optoelectronics/Information and Communications
  • INF-SIG/Sensors and Signal Processing/Information and Communications
  • INS-DET/Detection Devices/Instrumentation
  • INS-MEA/Measuring Instruments/Instrumentation
  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
16.04.2003

Leading Institute
Tbilisi State University, Georgia, Tbilisi

Collaborators

  • California State University, Bakersfield, USA, CA, Bakersfield\nUniversity of California, Riverside, USA, CA, Riverside\nPhilipps Universität / Department of Physics, Germany, Marburg

Project summary

The main objective of the project is to provide a theoretical basis and to elaborate recommendations for creation the following easily controllable semiconductor active elements:
- highly sensitive Hall sensor.

Easily controllable:


- high-frequency current generator
- high-frequency random number generator
- low-frequency current generator
- low-frequency random number generator.

To achieve the above-mentioned objective investigations in the following three directions will be carried out:

a) General investigation of the effect of transverse runaway (TR) of hot electrons in semiconductors for all kind of energy and momentum scattering mechanisms as well as for the arbitrary angle between the applied electric and magnetic fields. (Theoretical investigation).

b) Investigation of a possibility of realization of transverse breakdown (TB) from shallow and deep levels using the hot electron TR effect in the weak magnetic field. (Theoretical investigation).

c) Investigation of the magnetic field effect on formation and motion of electric domains under hopping conductivity conditions. (Experimental and theoretical investigation).

For each direction a possibility of occurrence of regular and chaotic oscillations will be studied.

Let us briefly discuss the state of art and essence of the problem for each of these directions.

- The TR of hot electrons is one of the interesting and efficient phenomena of occurrence of strongly nonlinear processes in semiconductors (nonlinear current-voltage characteristic with the negative differential conductivity, nonlinear regular and chaotic oscillations, etc.) This effect was first predicted and studied theoretically by our research team. So far investigations have been carried out only in crossed electric and magnetic fields and for some combinations of momentum and energy scattering mechanisms [1-4], since only in these conditions analytical solution of a relevant integrated equation was possible. On the other hand, other scattering mechanisms and other angles between fields can appear to be more optimal and efficient. Exactly this fact determines topicality of direction (a). To elucidate this question general solution of a complex integral equation by numerical methods is necessary.

- As is known, in usual conditions, for semiconductor transverse breakdown (TB) to take place sufficiently strong magnetic fields are required. During TB the free electron concentration increases sharply, which results in extreme instability of the sample and occurrence of nonlinear oscillations. The transverse runaway effect (TR) of hot electrons makes it possible to realize the TB in substantially lower magnetic fields, which, naturally, is very important from the viewpoint of performance of relevant high-frequency generators. Moreover, based on the TB effect under TR conditions superlow magnetic fields can be measured. The above-mentioned circumstances determine topicality of direction (b).

- Of special interest is the investigation of negative differential conductivity occurrence at the semiconductor hopping conductivity. The research team of the project authors was first to observe this phenomenon experimentally [5]. We carried out theoretical and experimental investigations of characteristics of the corresponding dynamic domains and the related nonlinear oscillations. These characteristics (and hence the characteristics of the relevant active elements) can be strongly affected by such external factors as a magnetic field and uniform sample compression. This determine topicality of direction (c).

In project implementation the sub-teams of theorists, experimenters and programmers of our team will participate. Supervision and monitoring of the activity of inpidual sub-teams will be performed by the project manager with the help of scientific supervisor and sub-team leaders. Active participation of foreign collaborators in discussion of the obtained results and in elaboration of a final set of recommendations for creation of active semiconductor elements is also envisaged. Joint implementation of some parts of the planned experiments is also possible.

References

[1] Kachlishvili Z.S. Soviet JETF. 78, 5, (1980).

[2] Kachlishvili Z.S., Chumburidze F.G., Soviet JETF, 87, 5, (1984).

[3] Kachlishvili Z.S., Metreveli N.K., Chumburidze F.G., Technical Physics, 70, 5 (2000).

[4] Kachlishvili Z.S., Metreveli N.K., Chumburidze F.G., Technical Physics Lett., 28, 9 (2002).

[5] Aladashvili D.I., Adamia Z.A., Tsakadze I.G. Solid State Com. 101 (1997).


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