Bell Telephone Laboratories

Purdue Research Foundation

Other

USA As Represented by Secretary of the Navy

American Telephone & Telegraph Co., At&t Bell Laboratories

Cree Research Inc.

James A Cooper, Jr

Donald E Blahut

Karvel K Thornber

Michael R Melloch

Federico Capasso

John Williams Palmour

Jerry M Woodall

Calvin H Carter, Jr

Shyam P Murarka

Dawon Kahng

Robert H Krambeck

Chuan C Chang

Theresa B Stellwag

Jason P Henning

Kipp J Schoen

A power semiconductor device includes a silicon carbide substrate and has at least a first layer or region formed above the substrate. The silicon carbide substrate has a pattern of pits formed thereon. The power semiconductor device further includes an ohmic metal disposed at least in the pits to form low-resistance ohmic contacts. Each pit of the pattern of pits has a depth that extends short of the first layer.

Methods of reducing the electrical and thermal resistance of SiC substrates and device made thereby

A dual-metal-trench silicon carbide Schottky pinch rectifier having a plurality of trenches formed in an n-type SiC substrate, with a Schottky contact having a relatively low barrier height on a mesa defined between adjacent ones of the trenches, and a Schottky contact having a relatively high barrier height at the bottom of each trench. The same metal used for the Schottky contact in each trench is deposited over the Schottky contact on the mesa. A simplified fabrication process is disclosed in which the high barrier height metal is deposited over the low barrier height metal and then used as an etch mask for reactive ion etching of the trenches to produce a self-aligned low barrier contact.

Dual-metal-trench silicon carbide Schottky pinch rectifier

A random access memory (RAM) cell in 6H-SiC having storage times when all bias is removed long enough to be considered nonvolatile. The nonvolatile random access memory (NVRAM) cell comprises a bit line, a charge storage device in silicon carbide, and a transistor in silicon carbide connecting the charge storage device to the bit line. The bipolar NVRAM cell has a bipolar transistor with a base region, an emitter region, and a floating collector region, wherein the charge storage device in the bipolar NVRAM is a p-n junction adjacent the floating collector region of the cell. The metal-oxide-semiconductor (MOS) NVRAM has a MOS field effect transistor (MOSFET) with a channel region, a source region, and a drain region, wherein the charge storage device in the MOS NVRAM is a MOS capacitor adjacent the drain region of the MOSFET.

Nonvolatile random access memory device having transistor and capacitor

A vertically integrated DRAM cell having a storage time of at least 4.5 hours at room temperature, formed from a wide-bandgap semiconductor such as GaAs or AlGaAs, in which an n-p-n bipolar access transistor is merged with a p-n-p storage capacitor, with the middle p-n layers being common to both. Similarly, a p-n-p transistor can be merged with an n-p-n storage capacitor.

Dynamic random access memory device

A transferred electron device is described in which the charge of the drifting packets is imaged perpendicular to the charge-packet direction so that essentially all of the packet-averaged, space-charge field is normal to the drift direction. This permits continuous formation of contiguous charge packets.

Transferred electron device

Semiconductor structures suitable for repeated velocity overshoot are described. The structure comprises at least two velocity overshoot sections with each section comprising a first semiconductor region having a rapid change in potential and a dimension such that the carrier transit time is comparable to or shorter than the mean scattering time and a second semiconductor region having a more gradual change in potential and a dimension such that the carrier transit time is sufficient to allow the energy relaxation time to be exceeded.

Repeated velocity overshoot semiconductor device

A memory device includes a relative lower bandgap energy first semiconductor layer, a relatively higher bandgap energy second semiconductor layer on the first, an alloy source rectifying to the first layer, a well for storing charge and a gate for controlling charge flow between the source and the well. The gate is formed on the second layer, as is a field plate for controlling the storage charge in the well. In one embodiment, a buried channel field effect transistor is combined with the basic memory device, with the charge content of the well controlling current flow between the source and drain of the buried channel FET.

Memory device

A method for making a MOSFET device (20) in a semiconductor body (10) includes the step of forming source and drain contact electrodes (12.1, 12.2) prior to growth of the gate oxide (10.3) and after formation of a high conductivity surface region (10.5). The exposed mutually opposing sidewall edges of each of the contact electrodes (12.1, 12.2) are coated with a sidewall silicon dioxide layer (15.1, 15.2), and the then exposed surface of the semiconductor body (10) between these sidewalls is etched to depth beneath the high conductivity surface region (10.5) in order to separate it into the source and drain regions (10.1, 10.2). Formation of the high conductivity region may be omitted by using Schottky barrier or impurity doped material for the contact electrodes (12.1, 12.2).

Method of fabricating MOS field effect transistors

Logic circuits, particularly of the integrated semiconductor type, are accessed at improved speeds by preventing pull-ups from occurring during the access time and by the inclusion of on-chip delay circuitry to avoid switching later stages in a manner to lose information while output nodes of earlier stages are high. All stages are activated in response to a single clock pulse edge.

Multistage logic circuit arrangement

The decoder portion of a programable logic array (PLA) includes logic devices at crosspoints defined between the word (x) lines and the address (y) lines characteristic of a decoder portion. The devices are operative to combine two or more word lines to activate a single word line in the associated read only memory (ROM) in response to one of two or more possible inputs. The technique is effective even in cases where 'don't care' conditions relating the two or more possible inputs cannot be found. A substantial reduction in chip area is achieved.

Programable logic array

The word conductors of a semiconductor integrated ROM are foreshortened where permitted by the organization of data in the memory. The space made available by the eliminated portions of the word conductors is used for electrical connection to the bit conductors from the sides of the array rather than at the ends. A space reduction of about thirty percent is achieved.

Integrated read only memory

An apparatus and a method for regenerating charge packets representing logical information in a charge transfer device uses a pattern of field plate electrodes and impurity zones to perform arithmetic operations. To regenerate a charge packet it is first multiplied by a factor dependent upon transfer imperfections. Then an amount of charge representing a logical 0 is substracted from the charge packet. Finally, the magnitude of the charge packet is limited to the amount of charge representing a logical 1.

Growing community of inventors

West Lafayette, IN, United States of America

James A Cooper, Jr