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Apparatus for Generation and Detection of Microwave Ultrasound

IP.com Disclosure Number: IPCOM000091017D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Anderson, JP: AUTHOR [+2]

Abstract

A block of single crystal gallium arsenide is arranged to act as both an oscillator and transducer for generation and detection of microwave ultrasound.

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Apparatus for Generation and Detection of Microwave Ultrasound

A block of single crystal gallium arsenide is arranged to act as both an oscillator and transducer for generation and detection of microwave ultrasound.

When gallium arsenide is subjected to an electric field exceeding approximately 2000 volts/cm, the current breaks into a Gunn effect oscillation. Such oscillation can then be used to generate ultrasonic waves within the GaAs. Thus, the GaAs acts as both a source and detector of microwave frequency ultrasound. The electrical Gunn oscillations act via the piezoelectricity of the GaAs to produce lattice strains by the surface generation process.

A block of gallium arsenide 1, which can be oriented in either the (110) or (111) direction, is polished flat on its lower surface 2 and is provided with a large area ohmic contact. The (110) and (111) directions are those directions in which a piezoelectric effect is produced by a longitudinal electric field. Other directions of the field with respect to crystal 1 are likewise possible. Gold can be used to cover the ohmic contact and then tin can be employed to cover the gold. Sample substrate 6 can also be covered with tin so that when gallium arsenide 1, in contact with substrate 6, is heated the tin on each surface flows so as to form, upon cooling, both a good acoustical bond and electrical contact shown at 7.

The top surface 3 of gallium arsenide 1 is lapped until the latter is of thickness L in accordance...