Trw Limited

Kei F Lau

Kuo-Hsiung Yen

Reynold S Kagiwada

Dale J Durand

Donald L Lochhead

Ke-Li Wang

James A Leaverton

An edge junction 10 with reduced parasitic inductance. The edge junction 10 has a laminar structure 22 including: a substrate 14; a first superconductive layer 12 deposited on a substrate 14; a first dielectric layer 16 deposited on the first superconductive layer 12; a second superconductive layer 18 deposited on the first dielectric layer 16; and a second dielectric layer 20 deposited on the second superconductive layer 18. The first and second superconductive layers 12 and 18 and the first and second dielectric layers 16 and 20 form a first laminar structure 22 having a planar segment 24 and a self-aligned ramp segment 26, the ramp segment 26 having a constantly-decreasing thickness and being connected to the planar segment 24 at an angle .theta. thereto. The edge junction 10 further includes a barrier layer 28 deposited on the first laminar structure 22; and a third superconductive layer 30 deposited on the barrier layer 28 to form: (i) a first Josephson junction 32 at the ramp segment 26 proximate the first superconductive layer 12 and (ii) a second Josephson junction 34 at the ramp segment 26 proximate the second superconductive layer 18. The overlap area of the first and the third superconductive layers 12 and 30 is greater than the overlap area of the second and the third superconductive layers 18 and 30, whereby the inductive parasitic effect of the first Josephson junction 32 on the second Josephson junction 34 is reduced. The superconductive layers 12, 18 and 30 are epitaxial with a c-axis in a direction substantially normal to the plane of the planar segment 24.

Self-aligned thin barrier high temperature superconductor edge junction

Acoustic wave devices employing shallow bulk acoustic waves rather than surface acoustic waves, to provide higher frequencies of operation and other significant advantages, such as less susceptibility to aging and less sensitivity to surface contamination. In each embodiment of the invention, a transmitting transducer and a receiving transducer are oriented on the surface of an anisotropic piezoelectric crystal to achieve substantial coupling of shallow bulk acoustic waves and essentially zero coupling of surface acoustic waves. In one embodiment of the invention, various types of grating filters utilize shallow bulk acoustic waves, and a set of parallel mechanical or electrical discontinuities at or near the surface of the crystal provide reflection of acoustic energy at a frequency determined by the spacing of the discontinuities. Uniformly spaced gratings provide bandpass filter operation, and gratings with graduated spacings provide for frequency compression or expansion. In another embodiment of the invention, variations in device characteristics due to temperature changes are compensated for by directing the shallow bulk waves through materials having favorable or opposite temperature characteristics compared with those of the material into which the waves are originally launched. In other embodiments of the invention, a shallow bulk acoustic wave includes a multistrip coupler, for transferring electroacoustic energy from one propagation path to another, for use in bandpass filters, delay lines or unidirectional transducers.

Shallow bulk acoustic wave devices

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Rolling Hills Estates, CA, United States of America

Kei F Lau