Accession Number : ADA335542

Title :   THz Radiation Source Trough Periodically Modulated Structures

Descriptive Note : Interim rept. no. 8, Sep-Nov 97

Corporate Author : TECHNISCHE UNIV VIENNA (AUSTRIA) INST FUER FESTKOERPERELEKTRONIK

Personal Author(s) : Gornik, Erich ; Rauch, C. ; Strasser, G. ; Unterrainer, K. ; Kersting, R.

PDF Url : ADA335542

Report Date : 04 DEC 1997

Pagination or Media Count : 7

Abstract : The work on the developement of new injection structures was continued. These experiments demonstrate the transition from coherent transport to band like scattering induced transport in a superlattice miniband. A mean free path of an injected electron in the order of 75 nm can be estimated for our ten period superlattices by using the experimental results for coherent and incoherent current at a fixed negative bias of 20 meV. This bias value corresponds exactly to the miniband width. Thus the onset of the Bloch oscillation regime appears at the value predicted by the Esaki-Tsu model. In the next period of the project we will manufacture individual bow-tie antennas coupled to the small mesas to enhance the emitted radiation. This step is also necessary for the other emission devices which are grown to demonstrate THz emission from plasma instabilities. We have observed THz emission from coherent plasma oscillations vertical to the surface of bulk semiconductors. The THz emission results from the response of carriers to the field screening induced by the ultrafast photoexcitation. Carriers are accelerated vertically to the surface and perform coherent oscillations around their new equilibrium state which leads to the emission of THz radiation. Our time-resolved measurements of the THz emission give insight into the dynamics of these plasma oscillations and their generation processes.

Descriptors :   *QUANTUM WELLS, *CHARGE CARRIERS, ELECTRON TRANSPORT, SUPERLATTICES, ELECTRIC FIELDS, COHERENT RADIATION, ELECTRON EMISSION, AUSTRIA, PLASMA OSCILLATION, BULK SEMICONDUCTORS, PLASMA INSTABILITIES.

Subject Categories : Electricity and Magnetism
      Quantum Theory and Relativity
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE