US Government As Represented by the Secretary of the Army

Melanie Will Cole

Pooran Chandra Joshi

Ryan C Toonen

Mathew P Ivill

Timothy P Weihs

Eric Ngo

Kezhou Xie

Clifford Hubbard

William Nothwang

Gary L Katulka

A pyroelectric device having a substrate and a first electrode overlying at least a portion of the substrate. A plurality of spaced apart nanometer sized pyroelectric elements are electrically connected to and extending outwardly from the first electrode so that each element forms a single domain. A dielectric material is deposited in the space between the individual elements and a second electrode spaced apart from said first electrode is electrically connected to said pyroelectric elements.

Pyroelectric device

An electronic device in the form a two-dimensional array of nanopillars extending generally normal to a substrate is provided. The nanopillars are made from a paraelectric or superparaelectric material. In addition, a linear dielectric medium is located between individual nanopillars. A two-dimensional array of paraelectric or superparaelectric nanopillars and a linear dielectric medium form the effective dielectric medium of a paraelectric or superparaelectric varactor. In some instances, the nanopillars are cylindrical nanopillars that have an average diameter and/or average height/length between 1-300 nanometers. In other instances, the nanopillars are quasi-nanoparticles that form self-aligned nano-junctions. In addition, each of the nanopillars has a single paraelectric or superparaelectric dipole domain therewithin. As such, each of the nanopillars can be void of crystallographic defects, polycrystallinity, interactions between ferroic domains, and defects due to ferroic domain walls.

Nano structured paraelectric or superparaelectric varactors for agile electronic systems

A compositionally stratified multi-layer BaSrTiO(BST) heterostructure material is described which includes a lower layer of crystallized BaSrTiOperovskite oxide where x is in the range of 0.36-0.44, inclusive, deposited on a substrate; an intermediate layer of crystallized BaSrTiOperovskite oxide where x is in the range of 0.23-0.27, inclusive, in contact with the lower layer; and an upper layer of crystallized BaSrTiOperovskite oxide where x in the range of 0.08-0.13, inclusive, in contact with the intermediate layer. A phase shifter and/or preselector tunable device including a compositionally stratified multi-layer BST hererostructure material is described according to the present invention. Temperature sensitivity of an inventive phase shifter is reduced by at least 70% in the temperature interval of 20 to 90&#xb0; C., inclusive, and by at least 14% in the temperature interval of &#x2212;10 to 20&#xb0; C., inclusive, compared to a compositionally homogeneous 60/40 BST material.

Thin film compositionally stratified multi-layer heterostructure for temperature insensitive low dielectric loss and enhanced tunability OTM communications devices and methods for fabrication thereof

A compositionally stratified multi-layer BaSrTiO(BST) heterostructure material is described which includes a lower layer of crystallized BaSrTiOperovskite oxide where x is in the range of 0.36-0.44, inclusive, deposited on a substrate; an intermediate layer of crystallized BaSrTiOperovskite oxide where x is in the range of 0.23-0.27, inclusive, in contact with the lower layer; and an upper layer of crystallized BaSrTiOperovskite oxide where x in the range of 0.08-0.13, inclusive, in contact with the intermediate layer. A phase shifter and/or preselector tunable device including a compositionally stratified multi-layer BST heterostructure material is described according to the present invention. Temperature sensitivity of an inventive phase shifter is reduced by at least 70% in the temperature interval of 20 to 90&#xb0; C., inclusive, and by at least 14% in the temperature interval of &#x2212;10 to 20&#xb0; C., inclusive, compared to a compositionally homogeneous 60/40 BST material.

Methods for fabrication of thin film compositionally stratified multi-layer heterostructures for temperature insensitive low dielectric loss and enhanced tunability OTM communications devices

Microelectromechanical systems (MEMS) include critical devices for various highly sensitive applications. However, MEMS operation may be impaired by vibration. A modular vibration control pedestal for integration with a MEMS is provided according to embodiments of the present invention which includes a piezoelectric perovskite oxide disposed on a substrate and a shape memory alloy component component disposed on the piezoelectric perovskite oxide. In particular embodiments of a MEMS device including a modular VCP, vibration is reduced by at least 50%.

Hybrid thin film heterostructure modular vibration control apparatus and methods for fabrication thereof

A NiSi-nSiC Ohmic contact is formed by pulsed laser ablation deposition (PLD) of NiSi source target deposited on a n-SiC substrate or SiC substrate wafer with SiC epilayer. The NiSi Ohmic contact on n-SiC was rapid thermal annealed at 950&#xb0; C. for 30 s in a Nambient. The resultant Ohmic contact is characterized by excellent current-voltage (I-V) characteristics, an abrupt void free contact-SiC interface, retention of the PLD as-deposited contact layer width, smooth surface morphology, and absence of residual carbon within the contact layer or at the interface. The detrimental effects of contact delamination due to stress associated with interfacial voiding; and wire bond failure, non-uniformity of current flow and SiC polytype alteration due to extreme surface roughness; have been eliminated as has electrical instability associated with carbon inclusions at the contact-SiC interface, after prolonged high temperature and power device operation.

Process for nickel silicide Ohmic contacts to n-SiC

A composite Pt/Ti/WSi/Ni Ohmic contact has been fabricated by a physical deposition process which uses electron beam evaporation and dc-sputter deposition. The Ni based composite Ohmic contact on n-Sic is rapid thermally annealed (RTA) at 950&#xb0; C. to 1000&#xb0; C. for 30 s to provide excellent current-voltage characteristics, an abrupt, void free contact-SiC interface, retention of the as-deposited contact layer width, smooth surface morphology and an absence of residual carbon within the contact layer and/or at the Ohmic contact-SiC interface. The annealed produced NiSi interfacial phase is responsible for the superior electrical integrity of the Ohmic contact to n-SiC. The effects of contact delamination due to stress associated with interfacial voiding has been eliminated. Wire bonding failure, non-uniform current flow and SiC polytype alteration due to extreme surface roughness have also been abolished. The Ohmic contact also avoids electrical instability associated with carbon inclusions within the contact metallization and/or at the contact-SiC interface, that occur under prolonged high temperature and power device operations. Overall, this contact is reliable for high temperature and high power operations and the stresses inclusive of use under those conditions.

Formulation and fabrication of an improved Ni based composite Ohmic contact to n-SiC for high temperature and high power device applications

A test apparatus and method is provided for dynamic thermal and electrical fatigue testing of a semiconductor in an operating environment, such as air, that mimic thermal and electrical stress in the semiconductor during high power switching in the operating environment. Comparisons of pre- and post-testing electrical measurements, i.e., current, voltage and contact resistance, are combined to provide an indicator or long-term reliability.

Test apparatus and method for reliability assessment of high power switching devices

A dielectric thin film material and method of preparation in which precursors are provided to form barium strontium titanate with lanthanum (La) added as a dopant. The precursors and La dopant are mixed with a solvent forming a solution which is deposited on a substrate to form a continuous film composition. In various embodiments, the dielectric thin film has a composition of (1-y)Ba Sr TiO &minus;(y)La, where y&equals;0 to 10-mol. The thin film material has dielectric and insulating properties suitable for tunable microwave applications.

Paraelectric thin film material and method statement of government interest

A method of deposition of a microwave frequency paraelectric BST-based thin film on a SiC substrate provides a resulting thin film-substrate structure which has no interfacial phases or element/chemical interdiffusion. For physical vapor deposition of the thin film, at least one of (i) thermally stable, refractory semiconductor substrate material is heat-treated during film deposition and (ii) the film-substrate structure is post-deposition heat treated, e.g., annealed, to achieve high quality film crystallinity with a fully developed film microstructure having desired microwave dielectric and insulating properties. For chemical solution deposition, the thin film is deposited onto a thermally stable, refractory semiconductor substrate material and is post-deposition heat treated to achieve a high quality film with a fully developed film microstructure having desired microwave dielectric and insulating properties.

Paraelectric thin film semiconductor material and method for producing the same

A composite Pt/Ti/WSi/Ni Ohmic contact has been fabricated by a physical deposition process which uses electron beam evaporation and dc-sputter deposition. The Ni based composite Ohmic contact on n-SiC is rapid thermally annealed (RTA) at 950&deg; C. to 1000&deg; C. for 30s to provide excellent current-voltage characteristics, an abrupt, void free contact-SiC interface, retention of the as-deposited contact layer width, smooth surface morphology and an absence of residual carbon within the contact layer and/or at the Ohmic contact-SiC interface. The annealed produced Ni Si interfacial phase is responsible for the superior electrical integrity of the Ohmic contact to n-SiC. The effects of contact delamination due to stress associated with interfacial voiding has been eliminated. Wire bonding failure, non-uniform current flow and SiC polytype alteration due to extreme surface roughness have also been abolished. The Ohmic contact also avoids electrical instability associated with carbon inclusions within the contact metallization and/or at the contact-SiC interface, that occur under prolonged high temperature and power device operations. Overall, this contact is reliable for high temperature and high power operations and the stresses inclusive of use under those conditions.

A GaN epilayaer grown on a lattice mismatched saphire substrate is subjected to rapid thermal processing in order the reduce the defect density especially in the proximate the top (device) surface of the GaN epilayer.

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Churchville, MD, United States of America

Melanie Will Cole