Raoul Schlesser

US Patent:

7678195, Mar 16, 2010

Filed:

Apr 6, 2006

Appl. No.:

11/399713

Inventors:

Raoul Schlesser - Cary NC, US
Vladimir Noveski - Chandler AZ, US
Zlatko Sitar - Raleigh NC, US

Assignee:

North Carolina State University - Raleigh NC

International Classification:

C30B 23/00

US Classification:

117 94, 117 84, 117 88, 117 90, 117 97, 117106, 117952

Abstract:

A method of growing bulk single crystals of an AlN on a single crystal seed is provided, wherein an AlN source material is placed within a crucible chamber in spacial relationship to a seed fused to the cap of the crucible. The crucible is heated in a manner sufficient to establish a temperature gradient between the source material and the seed with the seed at a higher temperature than the source material such that the outer layer of the seed is evaporated, thereby cleaning the seed of contaminants and removing any damage to the seed incurred during seed preparation. Thereafter, the temperature gradient between the source material and the seed is inverted so that the source material is sublimed and deposited on the seed, thereby growing a bulk single crystal of AlN.

US Patent:

7815970, Oct 19, 2010

Filed:

May 11, 2006

Appl. No.:

11/382806

Inventors:

Raoul Schlesser - Cary NC, US
Ramón R. Collazo - Raleigh NC, US
Zlatko Sitar - Raleigh NC, US

Assignee:

North Carolina State University - Raleigh NC

International Classification:

C23C 16/34

US Classification:

427255394, 4272557, 4273761, 427402

Abstract:

The present invention provides methods of preparing Group III-nitride films of controlled polarity and substrates coated with such controlled polarity films. In particular, the invention provides substrate preparation steps that optimize the substrate surface for facilitating growth of a Group III-polar film, an N-polar film, or a selectively patterned film with both a Group III-polar portion and an N-polar portion in precise positioning. The methods of the invention are particularly suited for use in CVD methods.

US Patent:

8414677, Apr 9, 2013

Filed:

Sep 10, 2009

Appl. No.:

12/556851

Inventors:

Raoul Schlesser - Cary NC, US
Rafael F. Dalmau - Cary NC, US
Vladimir Noveski - Chandler AZ, US
Zlatko Sitar - Raleigh NC, US

Assignee:

North Carolina State University - Raleigh NC

International Classification:

C22C 29/02

US Classification:

75239, 507 87, 507 961

Abstract:

The invention provides a method of forming a dense, shaped article, such as a crucible, formed of a refractory material, the method comprising the steps of placing a refractory material having a melting point of at least about 2900 C. in a mold configured to form the powder into an approximation of the desired shape. The mold containing the powder is treated at a temperature and pressure sufficient to form a shape-sustaining molded powder that conforms to the shape of the mold, wherein the treating step involves sintering or isostatic pressing. The shape-sustaining molded powder can be machined into the final desired shape and then sintered at a temperature and for a time sufficient to produce a dense, shaped article having a density of greater than about 90% and very low open porosity. Preferred refractory materials include tantalum carbide and niobium carbide.

US Patent:

20060280640, Dec 14, 2006

Filed:

Apr 5, 2006

Appl. No.:

11/398270

Inventors:

Raoul Schlesser - Cary NC, US
Rafael Dalmau - Cary NC, US
Vladimir Noveski - Chandler AZ, US
Zlatko Sitar - Raleigh NC, US

International Classification:

C22C 1/05
B22F 1/02
B29C 67/00
C04B 35/653
C04B 35/64

US Classification:

419014000, 419038000, 264682000, 264683000, 264654000, 264655000, 264125000, 264332000

Abstract:

The invention provides a method of forming a dense, shaped article, such as a crucible, formed of a refractory material, the method comprising the steps of placing a refractory material having a melting point of at least about 2900 C. in a mold configured to form the powder into an approximation of the desired shape. The mold containing the powder is treated at a temperature and pressure sufficient to form a shape-sustaining molded powder that conforms to the shape of the mold, wherein the treating step involves sintering or isostatic pressing. The shape-sustaining molded powder can be machined into the final desired shap and then sintered at a temperature and for a time sufficient to produce a dense, shaped article having a density of greater than about 90% and very low open porosity. Preferred refractory materials include tantalum carbide and niobium carbide.

US Patent:

20090250626, Oct 8, 2009

Filed:

Apr 3, 2009

Appl. No.:

12/418140

Inventors:

Raoul Schlesser - Raleigh NC, US
James M. LeMunyon - Oak Hill VA, US

International Classification:

H01J 37/20

US Classification:

25045511

Abstract:

The present invention includes a liquid sanitization device including one or more light emitting diodes (LED) that emit electro-magnetic radiation primarily at two or more distinct wavelengths. These wavelengths should be less than about 300 nm, preferably between about 210 to about 300 nm. The radiation from the light emitting diode or diodes kills or interacts with the DNA or RNA of pathogenic organisms in the liquid to prevent the organisms from reproducing or harming desirable organisms.

US Patent:

20110020602, Jan 27, 2011

Filed:

Sep 30, 2010

Appl. No.:

12/895018

Inventors:

Raoul Schlesser - Cary NC, US
Ramón R. Collazo - Raleigh NC, US
Zlatko Sitar - Raleigh NC, US

International Classification:

B32B 33/00
B32B 9/00
B05D 3/00

US Classification:

428141, 428189, 427271

Abstract:

The present invention provides methods of preparing Group III-nitride films of controlled polarity and substrates coated with such controlled polarity films. In particular, the invention provides substrate preparation steps that optimize the substrate surface for facilitating growth of a Group III-polar film, an N-polar film, or a selectively patterned film with both a Group III-polar portion and an N-polar portion in precise positioning. The methods of the invention are particularly suited for use in CVD methods.

US Patent:

20120021175, Jan 26, 2012

Filed:

Jul 19, 2011

Appl. No.:

13/185544

Inventors:

Baxter Moody - Raleigh NC, US
Rafael Dalmau - Raleigh NC, US
David Henshall - Raleigh NC, US
Raoul Schlesser - Raleigh NC, US

International Classification:

B32B 3/00
C04B 35/64
C01B 21/072

US Classification:

428141, 423412, 264676, 428220

Abstract:

Methods of preparing polycrystalline aluminum nitride materials that have high density, high purity, and favorable surface morphology are disclosed. The methods generally comprises pressing aluminum nitride powders to form a slug, sintering the slug to form a sintered, polycrystalline aluminum nitride boule, and optionally shaping the boule and/or polishing at least a portion of the boule to provide a finished substrate. The sintered, polycrystalline aluminum nitride materials beneficially are prepared without the use of any sintering aid or binder, and the formed materials exhibit excellent density, AlN purity, and surface morphology.

US Patent:

20120146023, Jun 14, 2012

Filed:

Dec 13, 2011

Appl. No.:

13/324261

Inventors:

Spalding Craft - Raleigh NC, US
Baxter Moody - Raleigh NC, US
Rafael Dalmau - Raleigh NC, US
Raoul Schlesser - Raleigh NC, US

International Classification:

H01L 29/04
H01L 21/20

US Classification:

257 51, 257 49, 438488, 438478, 257E29003, 257E2109

Abstract:

Disclosed are methods and materials useful in the preparation of semiconductor devices. In particular embodiments, disclosed are methods for engineering polycrystalline aluminum nitride substrates that are thermally matched to further materials that can be combined therewith. For example, the polycrystalline aluminum nitride substrates can be engineered to have a coefficient of thermal expansion (CTE) that is closely matched to the CTE of a semiconductor material and/or to a material that can be used as a growth substrate for a semiconductor material. The invention also encompasses devices incorporating such thermally engineered substrates and semiconductor materials grown using such thermally engineered substrates. The thermally engineered substrates are advantageous for overcoming problems caused by damage arising from CTE mismatch between component layers in semiconductor preparation methods and materials.