Jee H Kim

US Patent:

8354694, Jan 15, 2013

Filed:

Aug 13, 2010

Appl. No.:

12/855738

Inventors:

Stephen W. Bedell - Wappingers Falls NY, US
Jee H. Kim - Los Angeles CA, US
Siegfried L. Maurer - Stormville NY, US
Alexander Reznicek - Mount Kisco NY, US
Devendra K. Sadana - Pleasantville NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01L 29/66

US Classification:

257192, 257342

Abstract:

A p-type field effect transistor (PFET) having a compressively stressed channel and an n-type field effect transistor (NFET) having a tensilely stressed channel are formed. In one embodiment, a silicon-germanium alloy is employed as a device layer, and the source and drain regions of the PFET are formed employing embedded germanium-containing regions, and source and drain regions of the NFET are formed employing embedded silicon-containing regions. In another embodiment, a germanium layer is employed as a device layer, and the source and drain regions of the PFET are formed by implanting a Group IIIA element having an atomic radius greater than the atomic radius of germanium into portions of the germanium layer, and source and drain regions of the NFET are formed employing embedded silicon-germanium alloy regions. The compressive stress and the tensile stress enhance the mobility of charge carriers in the PFET and the NFET, respectively.

US Patent:

20120012167, Jan 19, 2012

Filed:

Jul 13, 2010

Appl. No.:

12/835238

Inventors:

Ahmed Abou-Kandil - Elmsford NY, US
Keith E. Fogel - Hopewell Junction NY, US
Jee H. Kim - Los Angeles CA, US
Mohamed Saad - White Plains NY, US
Devendra K. Sadana - Pleasantville NY, US

Assignee:

INTERNATIONAL BUSINESS MACHINES CORPORATION - Armonk NY

International Classification:

H01L 31/0288
H01L 31/18

US Classification:

136255, 438 72, 257E31128

Abstract:

A p-doped semiconductor layer of a photovoltaic device is formed employing an inert gas within a carrier gas. The presence of the inert gas within the carrier gas increases free hole density within the p-doped semiconductor layer. This decreases the Schottky barrier at an interface with a transparent conductive material layer, thereby significantly reducing the series resistance of the photovoltaic device. The reduction of the series resistance increases the open-circuit voltage, the fill factor, and the efficiency of the photovoltaic device. This effect is more prominent if the p-doped semiconductor layer is also doped with carbon, and has a band gap greater than 1.85V. The p-doped semiconductor material of the p-doped semiconductor layer can be hydrogenated if the carrier gas includes a mix of Hand the inert gas.

US Patent:

20120031476, Feb 9, 2012

Filed:

Aug 4, 2010

Appl. No.:

12/849966

Inventors:

Stephen W. Bedell - Wappingers Falls NY, US
Harold J. Hovel - Katonah NY, US
Daniel A. Inns - Palo Alto CA, US
Jee H. Kim - Los Angeles CA, US
Alexander Reznicek - Mount Kisco NY, US
Devendra K. Sadana - Pleasantville NY, US

Assignee:

INTERNATIONAL BUSINESS MACHINES CORPORATION - Armonk NY

International Classification:

H01L 31/0352
H01L 31/18

US Classification:

136255, 438 72, 257E31032

Abstract:

A photovoltaic device includes a composition modulated semiconductor structure including a p-doped first semiconductor material layer, a first intrinsic compositionally-graded semiconductor material layer, an intrinsic semiconductor material layer, a second intrinsic compositionally-graded semiconductor layer, and an n-doped first semiconductor material layer. The first and second intrinsic compositionally-graded semiconductor material layers include an alloy of a first semiconductor material having a greater band gap width and a second semiconductor material having a smaller band gap with, and the concentration of the second semiconductor material increases toward the intrinsic semiconductor material layer in the first and second compositionally-graded semiconductor material layers. The photovoltaic device provides an open circuit voltage comparable to that of the first semiconductor material, and a short circuit current comparable to that of the second semiconductor material, thereby increasing the efficiency of the photovoltaic device.

US Patent:

20120031477, Feb 9, 2012

Filed:

Aug 4, 2010

Appl. No.:

12/850272

Inventors:

Keith E. Fogel - Hopewell Junction NY, US
Jee H. Kim - Los Angeles CA, US
Devendra K. Sadana - Pleasantville NY, US
George S. Tulevski - White Plains NY, US
Ahmed Abou-Kandil - Elmsford NY, US
Hisham S. Mohamed - Clifton Park NY, US
Mohamed Saad - White Plains NY, US
Osama Tobail - Elmsford NY, US

Assignee:

EGYPT NANOTECHNOLOGY CENTER - Cairo-Alexandria
INTERNATIONAL BUSINESS MACHINES CORPORATION - Armonk NY

International Classification:

H01L 31/108
H01L 31/18

US Classification:

136255, 438 92, 977750, 977734, 257E31065

Abstract:

A Schottky-barrier-reducing layer is provided between a p-doped semiconductor layer and a transparent conductive material layer of a photovoltaic device. The Schottky-barrier-reducing layer can be a conductive material layer having a work function that is greater than the work function of the transparent conductive material layer. The conductive material layer can be a carbon-material layer such as a carbon nanotube layer or a graphene layer. Alternately, the conductive material layer can be another transparent conductive material layer having a greater work function than the transparent conductive material layer. The reduction of the Schottky barrier reduces the contact resistance across the transparent material layer and the p-doped semiconductor layer, thereby reducing the series resistance and increasing the efficiency of the photovoltaic device.

US Patent:

20120152352, Jun 21, 2012

Filed:

Dec 15, 2010

Appl. No.:

12/968490

Inventors:

Tze-Chiang Chen - Yorktown Heights NY, US
Jee H. Kim - Los Angeles CA, US
Devendra K. Sadana - Pleasantville NY, US
Ahmed Abou-Kandil - Elmsford NY, US
Mohamed Saad - White Plains NY, US

Assignee:

EGYPT NANOTECHNOLOGY CENTER - Cairo-Alexandria
INTERNATIONAL BUSINESS MACHINES CORPORATION - Armonk NY

International Classification:

H01L 31/0264
H01L 31/18

US Classification:

136261, 438 69, 257E31001

Abstract:

A germanium-containing layer is provided between a p-doped silicon-containing layer and a transparent conductive material layer of a photovoltaic device. The germanium-containing layer can be a p-doped silicon-germanium alloy layer or a germanium layer. The germanium-containing layer has a greater atomic concentration of germanium than the p-doped silicon-containing layer. The presence of the germanium-containing layer has the effect of reducing the series resistance and increasing the shunt resistance of the photovoltaic device, thereby increasing the fill factor and the efficiency of the photovoltaic device. In case a silicon-germanium alloy layer is employed, the closed circuit current density also increases.

US Patent:

20120318339, Dec 20, 2012

Filed:

Aug 30, 2012

Appl. No.:

13/599591

Inventors:

Ahmed Abou-Kandil - Elmsford NY, US
Keith E. Fogel - Hopewell Junction NY, US
Jee H. Kim - Los Angeles CA, US
Mohamed Saad - White Plains NY, US
Devendra K. Sadana - Pleasantville NY, US

Assignee:

INTERNATIONAL BUSINESS MACHINES CORPORATION - Armonk NY

International Classification:

H01L 31/075

US Classification:

136255

Abstract:

A p-doped semiconductor layer of a photovoltaic device is formed employing an inert gas within a carrier gas. The presence of the inert gas within the carrier gas increases free hole density within the p-doped semiconductor layer. This decreases the Schottky barrier at an interface with a transparent conductive material layer, thereby significantly reducing the series resistance of the photovoltaic device. The reduction of the series resistance increases the open-circuit voltage, the fill factor, and the efficiency of the photovoltaic device. This effect is more prominent if the p-doped semiconductor layer is also doped with carbon, and has a band gap greater than 1.85V. The p-doped semiconductor material of the p-doped semiconductor layer can be hydrogenated if the carrier gas includes a mix of Hand the inert gas.

US Patent:

20140109961, Apr 24, 2014

Filed:

Jan 2, 2014

Appl. No.:

14/146240

Inventors:

- Armonk NY, US
Harold J. Hovel - Katonah NY, US
Daniel A. Inns - Palo Alto CA, US
Jee H. Kim - Los Angeles CA, US
Alexander Reznicek - Mount Kisco NY, US
Devendra K. Sadana - Pleasantville NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01L 31/065
H01L 31/18
H01L 31/075

US Classification:

136255, 438 87

Abstract:

A photovoltaic device includes a composition modulated semiconductor structure including a p-doped first semiconductor material layer, a first intrinsic compositionally-graded semiconductor material layer, an intrinsic semiconductor material layer, a second intrinsic compositionally-graded semiconductor layer, and an n-doped first semiconductor material layer. The first and second intrinsic compositionally-graded semiconductor material layers include an alloy of a first semiconductor material having a greater band gap width and a second semiconductor material having a smaller band gap with, and the concentration of the second semiconductor material increases toward the intrinsic semiconductor material layer in the first and second compositionally-graded semiconductor material layers. The photovoltaic device provides an open circuit voltage comparable to that of the first semiconductor material, and a short circuit current comparable to that of the second semiconductor material, thereby increasing the efficiency of the photovoltaic device.