Jian Zhao

US Patent:

6423986, Jul 23, 2002

Filed:

Dec 8, 2000

Appl. No.:

09/719327

Inventors:

Jian J. Zhao - North Brunswick NJ

Assignee:

Rutgers, The State University - New Brunswick NJ

International Classification:

H01L 2987

US Classification:

257138, 257139, 257133, 257110, 257147, 257134

Abstract:

Power semiconductor devices have a plurality of semiconductor layers of alternating p-type and n-type conductivity and top and bottom device surfaces. The top semiconductor layer forms a control layer ( ). A semiconductor layer junction, remote from both device surfaces, forms a blocking p-n junction ( ) capable of sustaining the applied device voltage. A top ohmic contact overlays a top conductive region ( ) extending from the top surface into the control layer ( ). A conductive tub region ( ), spaced apart from the top conductive region ( ), extends from the top surface at least through the control layer ( ). A field effect region ( ) is disposed in the control layer ( ) between the top conductive region ( ) and tub region ( ). A gate contact ( ) is formed over the field effect region ( ) causing the creation and interruption of a conductive channel ( ) between the top conductive region ( ) and conductive tub region ( ) so as to turn the device on and off.

US Patent:

6841812, Jan 11, 2005

Filed:

Nov 7, 2002

Appl. No.:

10/289907

Inventors:

Jian Hui Zhao - North Brunswick NJ, US

Assignee:

United Silicon Carbide, Inc. - New Brunswick NJ

International Classification:

H01L 2980
H01L 2976
H01L 2994

US Classification:

257256, 257329, 257341

Abstract:

The present invention is a power semiconductor switch having a monolithically integrated low-voltage lateral junction field effect transistor (LJFET) controlling a high-voltage vertical junction field effect transistor (VJFET). The low-voltage LJFET conducting channel is double-gated by p+n junctions at opposite sides of the lateral channel. A buried p-type epitaxial layer forms one of the two p+n junction gates. A p+ region created by ion implantation serves as the p+ region for the second p+n junction gate. Both gates are electrically connected by a p+ tub implantation. The vertical channel of the vertical JFET is formed by converting part of the buried p-type epitaxial layer into n+ channel via n-type ion implantation.

US Patent:

7479672, Jan 20, 2009

Filed:

Apr 9, 2007

Appl. No.:

11/784613

Inventors:

Jian H. Zhao - North Brunswick NJ, US

Assignee:

Rutgers, The State University - New Brunswick NJ

International Classification:

H01L 29/80

US Classification:

257256, 257134, 257135, 257272, 257192, 257195, 257274, 257E27148

Abstract:

A semiconductor vertical junction field effect power transistor formed by a semiconductor structure having top and bottom surfaces and including a plurality of semiconductor layers with predetermined doping concentrations and thicknesses and comprising at least a bottom layer as drain layer, a middle layer as blocking and channel layer, a top layer as source layer. A plurality of laterally spaced U-shaped trenches with highly vertical side walls defines a plurality of laterally spaced mesas. The mesas are surrounded on the four sides by U-shaped semiconductor regions having conductivity type opposite to that of the mesas forming U-shaped pn junctions and defining a plurality of laterally spaced long and vertical channels with a highly uniform channel opening dimension. A source contact is formed on the top source layer and a drain contact is formed on the bottom drain layer. A gate contact is formed on the bottom of the U-shaped trenches for the purpose of creating and interrupting the vertical channels so as to turn on and turn off the transistor.

US Patent:

20050067630, Mar 31, 2005

Filed:

Sep 25, 2003

Appl. No.:

10/671233

Inventors:

Jian Zhao - North Brunswick NJ, US

International Classification:

H01L029/74
H01L031/111

US Classification:

257134000, 257135000, 257136000

Abstract:

A semiconductor vertical junction field effect power transistor formed by a semiconductor structure having top and bottom surfaces and including a plurality of semiconductor layers with predetermined doping concentrations and thicknesses and comprising at least a bottom layer as drain layer, a middle layer as blocking and channel layer, a top layer as source layer. A plurality of laterally spaced U-shaped trenches with highly vertical side walls defines a plurality of laterally spaced mesas. The mesas are surrounded on the four sides by U-shaped semiconductor regions having conductivity type opposite to that of the mesas forming U-shaped pn junctions and defining a plurality of laterally spaced long and vertical channels with a highly uniform channel opening dimension. A source contact is formed on the top source layer and a drain contact is formed on the bottom drain layer. A gate contact is formed on the bottom of the U-shaped trenches for the purpose of creating and interrupting the vertical channels so as to turn on and turn off the transistor.

US Patent:

20100148224, Jun 17, 2010

Filed:

Jan 19, 2009

Appl. No.:

12/355978

Inventors:

Jian H. Zhao - North Brunswick NJ, US

Assignee:

Rutgers, The State University of New Jersey - New Brunswick NJ

International Classification:

H01L 29/80

US Classification:

257263, 257E2931

Abstract:

A semiconductor vertical junction field effect power transistor formed by a semiconductor structure having top and bottom surfaces and including a plurality of semiconductor layers with predetermined doping concentrations and thicknesses and comprising at least a bottom layer as drain layer, a middle layer as blocking and channel layer, a top layer as source layer. A plurality of laterally spaced U-shaped trenches with highly vertical side walls defines a plurality of laterally spaced mesas. The mesas are surrounded on the four sides by U-shaped semiconductor regions having conductivity type opposite to that of the mesas forming U-shaped pn junctions and defining a plurality of laterally spaced long and vertical channels with a highly uniform channel opening dimension. A source contact is formed on the top source layer and a drain contact is formed on the bottom drain layer. A gate contact is formed on the bottom of the U-shaped trenches for the purpose of creating and interrupting the vertical channels so as to turn on and turn off the transistor.

US Patent:

53230302, Jun 21, 1994

Filed:

Sep 24, 1993

Appl. No.:

8/126837

Inventors:

Thomas E. Koscica - Clark NJ
Jian H. Zhao - North Brunswick NJ

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

H01L 29161
H01L 29205

US Classification:

257195

Abstract:

The present Field Effect Real Space Transistor, or FERST, is a four terminal device with S, G, C, and D representing the source, gate, collector, and drain, respectively. The S, G, and D terminals can be likened to those of the MODFET. The collector name is borrowed from other real space transfer devices. Surrounding the entire device is an oxygen implant isolation. The source and drain ohmic contacts penetrate to the 150. ANG. GaAs channel while the collector ohmic contact does not penetrate due to its position upon an elevated submesa. AlGaAs layers are used as etch stops during processing of the device and a Schottky barrier gate is placed on an undoped layer. Channel carriers are provided by modulation doping the lower barrier of the channel. An Al. sub. 35 Ga. sub. 65 As layer on the upper channel side is used as a real space transfer barrier. In operation and under appropriate bias conditions, real space transfer occurs across this upper barrier and into the collector.

US Patent:

55699430, Oct 29, 1996

Filed:

Sep 1, 1995

Appl. No.:

8/522894

Inventors:

Thomas E. Koscica - Clark NJ
Jian H. Zhao - North Brunswick NJ

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

H01L 310328
H01L 310336
H01L 2980

US Classification:

257192

Abstract:

A heterostructure semiconductor device having source and drain electrodes sistively coupled to opposite ends of a channel, a barrier layer on one side of the channel, a delta doped layer in the channel or within a given distance of it, a gate electrode on the barrier so as to form a Schottky diode and at least one collector electrode mounted on said barrier layer. The collector electrode or electrodes can be resistively coupled to the barrier layer, but preferably the coupling is such as to form a Schottky diode. Changes to the gate bias affect the source current through the field effect mechanism. The collector current depends on the transfer of heated, energized carriers out of the channel over the front heterobarrier. At low gate bias, electrons entering the source travel to the drain while none travel to the collector. Energized carriers are localized to the depletion region due its high electric field drop.

US Patent:

6107649, Aug 22, 2000

Filed:

Jun 10, 1998

Appl. No.:

9/095481

Inventors:

Jian H. Zhao - North Brunswick NJ

Assignee:

Rutgers, The State University - New Brunswick NJ

International Classification:

H01L 29745
H01L 2978

US Classification:

257138

Abstract:

Power semiconductor devices have a plurality of semiconductor layers of alternating p-type and n-type conductivity and top and bottom device surfaces. A layer of the top surface forms a control layer. A semiconductor layer junction, remote from top and bottom device surfaces, forms a blocking p-n junction capable of sustaining the applied device voltage. A top ohmic contact overlays a top conductive region extending from the top surface into the control layer. A conductive tub region, spaced apart from the top conductive region, extends from the top surface at least through the control layer. A field effect region is disposed in the control layer between the top conductive region and tub region. A gate contact is formed over the field effect region causing the creation and interruption of a conductive channel between the top conductive region and the conductive tub region so as to turn the device on and off. In one device embodiment, a separate latch-on gate overlying the conductive tub is provided for device turn-on.