Wide-band-gap oxides such as SrTiO3 are shown to be critical tests of theories of Schottky barrier heights based on metal-induced gap states and charge neutrality levels. This theory is reviewed and used to calculate the Schottky barrier heights and band offsets for many important high dielectric constant oxides on Pt and Si. Good agreement with experiment is found for barrier heights. The band offsets for electrons on Si are found to be small for many key oxides such as SrTiO3 and Ta2O5 which limit their utility as gate oxides in future silicon field effect transistors. The calculations are extended to screen other proposed oxides such as BaZrO3. ZrO2, HfO2, La2O3, Y2O3, HfSiO4, and ZrSiO4. Predictions are also given for barrier heights of the ferroelectric oxides Pb1−xZrxTiO3 and SrBi2Ta2O9 which are used in nonvolatile memories.

Band offsets of wide-band-gap oxides and implications for future electronic devices

The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

http://science.sciencemag.org/content/sci/311/5758/208.full.pdf

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems' applications, and permittivity and loss in ferroelectric films-important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures. (c) 2006 American Institute of Physics.

/pdf/ferroelectric-thin-films-review-of-materials-properties-and-rc7umdkxk5.pdf

Ferroelectric thin films: Review of materials, properties, and applications

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

A review of the properties of ferroelectric materials that are relevant to microwave tunable devices is presented: we discuss the theory of dielectric response of tunable bulk materials and thin films; the experimental results from the literature and from own work are reviewed; the correspondence between the theoretical results and the measured properties of tunable materials is critically analyzed; nominally pure, real (defected), and composite bulk materials and thin films are addressed. In addition, techniques for characterization of tunable ferroelectrics and applications of these materials are briefly presented.

Ferroelectric materials for microwave tunable applications

Thin films of barium-strontium titanate (Ba,Sr)TiO3 (BSTO) have been investigated for use as a capacitor dielectric for future generations of dynamic random-access memory (DRAM). This paper describes progress made in the preparation of BSTO films by liquid-source metal-organic chemical vapor deposition (LS-MOCVD) and the issues related to integrating films of BSTO into a DRAM capacitor. Films of BSTO deposited on planar Pt electrodes meet the electrical requirements needed for future DRAM. The specific capacitance and charge loss are found to be strongly dependent on the details of the BSTO deposition, the choice of the lower electrode structure, the microstructure of the BSTO, the post-electrode thermal treatments, BSTO dopants, and thin-film stress. Films of BSTO deposited on patterned Pt electrodes with a feature size of 0.2 µm are found to have degraded properties compared to films on large planar structures, but functional bits have been achieved on a DRAM test site at 0.20-µm ground rules. Mechanisms influencing specific capacitance and charge loss of BSTO films are described, as are the requirements for the electrode and barrier materials used in stacked-capacitor structures, with emphasis given to the properties of the Pt/TaSi(N) electrode/barrier system. Major problems requiring additional investigation are outlined.

(Ba,Sr)TiO 3 dielectrics for future stacked- capacitor DRAM

The dielectric relaxation of Ba0.7Sr0.3TiO3 thin films was investigated up to K band (20 GHz) using time domain and frequency domain measurements. Our results show that from 1 mHz to 20 GHz, the dielectric relaxation of the complex capacitance of Ba0.7Sr0.3TiO3 thin films can be understood in terms of a power law dependence known as the Curie–von Schweidler law. The small dispersion (less than 7% decrease in capacitance from 1 mHz to 20 GHz) and low loss (loss angle less than 0.006 at 20 GHz) measured in Ba0.7Sr0.3TiO3 thin films indicate that these films are applicable to device application up to at least K band.

Dielectric relaxation of Ba0.7Sr0.3TiO3 thin films from 1 mHz to 20 GHz

Noble metal plating on a preexisting seed layer is used in the fabrication of electrodes for DRAM and FRAM. The plating may be spatially selective or nonselective. In the nonselective case, a blanket film is first plated and then patterned after deposition by spatially selective material removal. In the selective case, the plated deposits are either selectively grown in lithographically defined areas by a through-mask plating technique, or selectively grown as a conformal coating on the exposed regions of a preexisting electrode structure. A diamond-like carbon mask can be used in the plating process. A self-aligned process is disclosed for selectively coating insulators in a through-mask process.

Plating of noble metal electrodes for DRAM and FRAM

There has been growing interest in the use of materials with the perovskite structure as a dielectric for capacitors in dynamic random access memory chips. The heightened activity in this field is exemplified by the nearly exponential increase in the number of patents issued during the past 5 years. At the present time, a fully functional DRAM with a capacitor incorporating these high-dielectric constant materials has not been demonstrated. All existing DRAMs use silicon dioxide and/or silicon nitride as the capacitor dielectric. This paper will describe the potential advantages of incorporating high-dielectric materials into the storage capacitor of a DRAM and review the requirements of the high-dielectric layer when used in a simple stack capacitor structure suitable for the GBit generation of DRAM. Recent advances in this technology are reviewed and the major issues, which could be potential show-stoppers and still need to be resolved, are described.

A review of high dielectric materials for DRAM capacitors

A DNA sequencing device which integrates transverse conducting electrodes for the measurement of electrode currents during DNA translocation through a nanopore has been nanofabricated and characterized A focused electron beam (FEB) milling technique, capable of creating features on the order of 1 nm in diameter, was used to create the nanopore The device was characterized electrically using gold nanoparticles as an artificial analyte with both DC and AC measurement methods Single nanoparticle/electrode interaction events were recorded A low-noise, high-speed transimpedance current amplifier for the detection of nano- to picoampere currents at microsecond time scales was designed, fabricated and tested for future integration with the nanopore device

David E. Kotecki

Papers

(Ba,Sr)TiO 3 dielectrics for future stacked- capacitor DRAM

Dielectric relaxation of Ba0.7Sr0.3TiO3 thin films from 1 mHz to 20 GHz

Plating of noble metal electrodes for DRAM and FRAM

A review of high dielectric materials for DRAM capacitors

Nanopore with Transverse Nanoelectrodes for Electrical Characterization and Sequencing of DNA.