Generation of Microwave Radiation in InSb by Acoustoelectric Amplification.
MICHIGAN UNIV ANN ARBOR ELECTRON PHYSICS LAB
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On the basis of experimental results obtained herein, an original theoretical model is developed for the electrical instability manifested by microwave radiation from InSb. The model depicts a continuous nucleation of acoustic disturbances at plasma regions which are localized in the vicinity of the contacts, and subsequent amplification of off-axis acoustic waves as they propagate into the bulk of the InSb specimen. The radiation arises via the conversion of the acoustical energy into microwave radiation hence it is assumed that the field dependence of the radiation is determined by the growth rate of the acoustoelectric instability. A general formulation of the off-axis acoustoelectric interaction, specialized for III-V semiconductor compounds, is fully developed. The particular case of the interaction in n-type 110 -oriented InSb is analyzed and described in detail. It is shown that the major correction required to extend the hydrodynamical theory of the acoustoelectric interaction to microwave frequencies is the inclusion of electron inertial terms. Further analysis reveals that the physical mechanism for the emergence of a separate high-field mode of acoustic-wave amplification Mode I is the drift-enhanced quenching of electron diffusion effects. Low-field 10 GHz noise radiation and attendant RF current oscillations are generated in 10-mm long specimens of n-type, 110-oriented InSb at 77K. Author
- Solid State Physics