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Gallium Arsenide Gunn Oscillator to Excite Surface Acoustic Waves

IP.com Disclosure Number: IPCOM000073733D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Lean, EG: AUTHOR [+2]

Abstract

A GaAs Gunn oscillator is used to excite surface acoustic waves in piezoelectric and nonpiezoelectric substrates.

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Gallium Arsenide Gunn Oscillator to Excite Surface Acoustic Waves

A GaAs Gunn oscillator is used to excite surface acoustic waves in piezoelectric and nonpiezoelectric substrates.

In drawing A, a Gunn oscillator 1 with cathode-anode separation a is placed on top of a piezoelectric substrate 2. As the Gunn oscillator oscillates, a domain travels at a velocity of c (approx. 10/7/ cm/sec) from the cathode 3 to anode 4. The frequency of the oscillator is given by v/R. Associated with the domain in a GaAs Gunn oscillator, is a strong electric field which extends beyond the GaAs surface. In spite of the difference in velocities, the electric field can couple to the nearby piezoelectric substrate 2, if there is a grating 5 with the period d between the Gunn oscillator 1 and the substrate 2. The period d is obtained from the phase matching condition and is given by: d = Lambda v over c - v where Lambda is the wavelength of the Gunn oscillator; v and c are the velocities of the surface acoustic wave in the substrate and the Gunn domain, respectively. The field in the Gunn domain will couple efficiently into surface acoustic waves 6 in the substrate.

Typically, v = 3 x 10/5/ cm/sec, c = 3 x 10/7/ cm/sec, Lambda approx.= 100 Lambda, where Lambda is the acoustic wavelength in the substrate. The above equation gives d approx. Lambda, which is a very reasonable value in practical fabrication.

The grating 5 can be metal strips, or dielectric strips or grooves with the proper se...