Peter M Sheldon

US Patent:

8006566, Aug 30, 2011

Filed:

Jul 28, 2006

Appl. No.:

11/722981

Inventors:

Bhushan L. Sopori - Denver CO, US
Peter Sheldon - Lakewood CO, US

Assignee:

Alliance for Sustainable Energy, LLC - Golden CO

International Classification:

G01L 1/24

US Classification:

73800, 73760, 73777, 438 14

Abstract:

A method for screening silicon-based wafers used in the photovoltaic industry is provided herewith.

US Patent:

46145648, Sep 30, 1986

Filed:

Dec 4, 1984

Appl. No.:

6/678202

Inventors:

Peter Sheldon - Golden CO
Russell E. Hayes - Boulder CO

Assignee:

The United States of America as represented by the United States
Department of Energy - Washington DC

International Classification:

C03B 2300
H01L 21205
H01L 21365
H01L 21306

US Classification:

156657

Abstract:

A process is disclosed for selectively patterning epitaxial film growth on a semiconductor substrate. The process includes forming a masking member on the surface of the substrate, the masking member having at least two layers including a first layer disposed on the substrate and the second layer covering the first layer. A window is then opened in a selected portion of the second layer by removing that portion to expose the first layer thereunder. The first layer is then subjected to an etchant introduced through the window to dissolve a sufficient amount of the first layer to expose the substrate surface directly beneath the window, the first layer being adapted to preferentially dissolve at a substantially greater rate than the second layer so as to create an overhanging ledge portion with the second layer by undercutting the edges thereof adjacent to the window. The epitaxial film is then deposited on the exposed substrate surface directly beneath the window. Finally, an etchant is introduced through the window to dissolve the remainder of the first layer so as to lift-off the second layer and materials deposited thereon to fully expose the balance of the substrate surface.

US Patent:

61692468, Jan 2, 2001

Filed:

Sep 8, 1998

Appl. No.:

9/149430

Inventors:

Xuanzhi Wu - Golden CO
Peter Sheldon - Lakewood CO
Timothy J. Coutts - Lakewood CO

Assignee:

Midwest Research Institute - Kansas City MO

International Classification:

H01L 3100

US Classification:

136265

Abstract:

A photovoltaic device has a buffer layer zinc stannate Zn. sub. 2 SnO. sub. 4 disposed between the semiconductor junction structure and the transparent conducting oxide (TCO) layer to prevent formation of localized junctions with the TCO through a thin window semiconductor layer, to prevent shunting through etched grain boundaries of semiconductors, and to relieve stresses and improve adhesion between these layers.

US Patent:

54562058, Oct 10, 1995

Filed:

Jun 1, 1993

Appl. No.:

8/069405

Inventors:

Peter Sheldon - Lakewood CO

Assignee:

Midwest Research Institute - Kansas City MO

International Classification:

C30B 2516

US Classification:

117 85

Abstract:

A system for monitoring the growth of crystalline films on stationary or rotating substrates includes a combination of some or all of the elements including a photodiode sensor for detecting the intensity of incoming light and converting it to a measurable current, a lens for focusing the RHEED pattern emanating from the phosphor screen onto the photodiode, an interference filter for filtering out light other than that which emanates from the phosphor screen, a current amplifier for amplifying and converting the current produced by the photodiode into a voltage, a computer for receiving the amplified photodiode current for RHEED data analysis, and a graphite impregnated triax cable for improving the signal to noise ratio obtained while sampling a stationary or rotating substrate. A rotating stage for supporting the substrate with diametrically positioned electron beam apertures and an optically encoded shaft can also be used to accommodate rotation of the substrate during measurement.

US Patent:

49639498, Oct 16, 1990

Filed:

Sep 30, 1988

Appl. No.:

7/251484

Inventors:

Mark W. Wanlass - Golden CO
Peter Sheldon - Lakewood CO

Assignee:

The United States of America as represented of the United States
Department of Energy - Washington DC

International Classification:

H01L 29205
H01L 3106

US Classification:

357 16

Abstract:

A substrate structure for an InP-based semiconductor device having an InP based film is disclosed. The substrate structure includes a substrate region having a lightweight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice-matched at one end to the GaAs layer and substantially lattice-matched at the opposite end to the InP-based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region, and the InP-based device.

US Patent:

55889956, Dec 31, 1996

Filed:

May 3, 1995

Appl. No.:

8/434181

Inventors:

Peter Sheldon - Lakewood CO

Assignee:

Midwest Research Institute - Kansas City MI

International Classification:

C30B 2516

US Classification:

117201

Abstract:

A system for monitoring the growth of crystalline films on stationary or rotating substrates includes a combination of some or all of the elements including a photodiode sensor for detecting the intensity of incoming light and converting it to a measurable current, a lens for focusing the RHEED pattern emanating from the phosphor screen onto the photodiode, an interference filter for filtering out light other than that which emanates from the phosphor screen, a current amplifier for amplifying and convening the current produced by the photodiode into a voltage, a computer for receiving the amplified photodiode current for RHEED data analysis, and a graphite impregnated triax cable for improving the signal to noise ratio obtained while sampling a stationary or rotating substrate. A rotating stage for supporting the substrate with diametrically positioned electron beam apertures and an optically encoded shaft can also be used to accommodate rotation of the substrate during measurement.

US Patent:

59221429, Jul 13, 1999

Filed:

Nov 18, 1996

Appl. No.:

8/746798

Inventors:

Xuanzhi Wu - Golden CO
Timothy J. Coutts - Lakewood CO
Peter Sheldon - Lakewood CO
Douglas H. Rose - Golden CO

Assignee:

Midwest Research Institute

International Classification:

H01L 3100

US Classification:

136260

Abstract:

A photovoltaic device having a substrate, a layer of Cd. sub. 2 SnO. sub. 4 disposed on said substrate as a front contact, a thin film comprising two or more layers of semiconductor materials disposed on said layer of Cd. sub. 2 SnO. sub. 4, and an electrically conductive film disposed on said thin film of semiconductor materials to form a rear electrical contact to said thin film. The device is formed by RF sputter coating a Cd. sub. 2 SnO. sub. 4 layer onto a substrate, depositing a thin film of semiconductor materials onto the layer of Cd. sub. 2 SnO. sub. 4, and depositing an electrically conductive film onto the thin film of semiconductor materials.

US Patent:

57121877, Jan 27, 1998

Filed:

Nov 9, 1995

Appl. No.:

8/555621

Inventors:

Xiaonan Li - Golden CO
Peter Sheldon - Lakewood CO

Assignee:

Midwest Research Institute - Kansas City MO

International Classification:

H01L 2120
H01L 3118

US Classification:

437109

Abstract:

A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.