Sarita Thakoor

US Patent:

52068293, Apr 27, 1993

Filed:

Oct 24, 1990

Appl. No.:

7/603935

Inventors:

Sarita Thakoor - Pasadena CA
Anilkumar P. Thakoor - Pasadena CA

International Classification:

G11C 1142

US Classification:

365117

Abstract:

An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

US Patent:

51961016, Mar 23, 1993

Filed:

Feb 5, 1991

Appl. No.:

7/651329

Inventors:

Sarita Thakoor - Pasadena CA

Assignee:

Califoria Institute of Technology - Pasadena CA

International Classification:

C23C 1434

US Classification:

20419226

Abstract:

Composite films of multicomponent materials, such as oxides and nitrides, e. g. , lead zirconate titanate, are deposited by dc magnetron sputtering, employing a rotating substrate holder, which rotates relative to a plurality of targets, one target for each metal element of the multicomponent material. The sputtering is carried out in a reactive atmosphere. The substrates on which the layers are deposited are at ambient temperature. Following deposition of the composite film, the film is heated to a temperature sufficient to initiate a solid state reaction and form the final product, which is substantially single phase and substantially homogeneous.

US Patent:

53728599, Dec 13, 1994

Filed:

Oct 20, 1992

Appl. No.:

7/963974

Inventors:

Sarita Thakoor - Covina CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

B05D 306
B05D 512
B05D 302

US Classification:

427551

Abstract:

Thin film ferroelectric capacitors (10) comprising a ferroelectric film (18) sandwiched between electrodes (16 and 20) for nonvolatile memory operations are rendered more stable by subjecting the capacitors to an anneal following deposition of the top electrode (20). The anneal is done so as to form the interface (22) between the ferroelectric film and the top electrode. Heating in an air oven, laser annealing, or electron bombardment may be used to form the interface. Heating in an air oven is done at a temperature at least equal to the crystallization temperature of the ferroelectric film. Where the ferroelectric film comprises lead zirconate titanate, annealing is done at about 550. degree. to 600. degree. C. for about 10 to 15 minutes. The formation treatment reduces the magnitude of charge associated with the non-switching pulse in the thin film ferroelectric capacitors.

US Patent:

61081116, Aug 22, 2000

Filed:

Feb 6, 1997

Appl. No.:

8/795954

Inventors:

Sarita Thakoor - Covina CA
Anilkumar P. Thakoor - Covina CA

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

G11C 1122
H01G 706

US Classification:

359107

Abstract:

Photoresponse from a ferroelectric optical computing device, such as a memory cell or a logic switch, is increased by either illuminating the regions of the ferroelectric crystal under the electrode edges in a sandwich structure device or by aligning the principal axis of the ferroelectric crystal parallel to the linear polarization vector of the optical beam. Device density is increased by reducing the beam size using a small near-field optical fiber. Device evaluation including imprint failure susceptibility is performed by illuminating each ferroelectric optical computing device in a large array of such devices and storing the device address of any device whose response departs from a normal range.

US Patent:

48397008, Jun 13, 1989

Filed:

Dec 16, 1987

Appl. No.:

7/133897

Inventors:

Sarita Thakoor - Pasadena CA
Taher Daud - La Crescenta CA
Aniklumar P. Thakoor - Pasadena CA

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

H01L 4500
H01L 2712
H01L 4902
H01L 2912

US Classification:

357 2

Abstract:

A solid-state variable resistance device (10) whose resistance can be repeatedly altered by a control signal over a wide range, and which will remain stable after the signal is removed, is formed on an insulated layer (14), supported on a substrate (12) and comprises a set of electrodes (16a, 16b) connected by a layer (18) of material, which changes from an insulator to a conductor upon the injection of ions, covered by a layer (22) of material with insulating properties which permit the passage of ions, overlaid by an ion donor material (20). The ion donor material is overlaid by an insulating layer (24) upon which is deposited a control gate (26) located above the contacts. In a preferred embodiment, the variable resistance material comprises WO. sub. 3, the ion donor layer comprises Cr. sub. 2 O. sub. 3, and the layers sandwiching the ion donor layer comprise silicon monoxide.

US Patent:

47268905, Feb 23, 1988

Filed:

Aug 12, 1985

Appl. No.:

6/764812

Inventors:

Sarita Thakoor - Pasadena CA
James L. Lamb - Los Angeles CA
Anilkumar P. Thakoor - Pasadena CA
Satish K. Khanna - Pasadena CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

C23C 1434

US Classification:

20419224

Abstract:

Thin films of niobium nitride with high superconducting temperature (T. sub. c) of 15. 7. degree. K. are deposited on substrates held at room temperature (. about. 90. degree. C. ) by heat sink throughout the sputtering process. Films deposited at P. sub. Ar >12. 9. +-. 2 mTorr exhibit higher T. sub. c with increasing P. sub. N2,I, with the highest T. sub. c achieved at P. sub. N2,I =3. 7. +-. 2 mTorr and total sputtering pressure P. sub. tot =16. 6. +-. 4. Further increase of N. sub. 2 injection starts decreasing T. sub. c.

US Patent:

59231823, Jul 13, 1999

Filed:

May 23, 1996

Appl. No.:

8/652841

Inventors:

Sarita Thakoor - Covina CA
Anilkumar P. Thakoor - Covina CA

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

G11C 700

US Classification:

324765

Abstract:

Photoresponse from a ferroelectric optical computing device, such as a memory cell or a logic switch, is increased by either illuminating the regions of the ferroelectric crystal under the electrode edges in a sandwich structure device or by aligning the principal axis of the ferroelectric crystal parallel to the linear polarization vector of the optical beam. Device density is increased by reducing the beam size using a small near-field optical fiber. Device evaluation including imprint failure susceptibility is performed by illuminating each ferroelectric optical computing device in a large array of such devices and storing the device address of any device whose response departs from a normal range.

US Patent:

56215592, Apr 15, 1997

Filed:

Apr 18, 1994

Appl. No.:

8/228730

Inventors:

Sarita Thakoor - Covina CA
Anilkumar P. Thakoor - Covina CA

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

G11C 1122
H01G 706

US Classification:

359107

Abstract:

Photoresponse from a ferroelectric optical computing device, such as a memory cell or a logic switch, is increased by either illuminating the regions of the ferroelectric crystal under the electrode edges in a sandwich structure device or by aligning the principal axis of the ferroelectric crystal parallel to the linear polarization vector of the optical beam. Device density is increased by reducing the beam size using a small near-field optical fiber. Device evaluation including imprint failure susceptibility is performed by illuminating each ferroelectric optical computing device in a large array of such devices and storing the device address of any device whose response departs from a normal range.