Structure of Ba2Cu(BO3)2

As part of our program in the synthesis and characterization of new solid-state borates, we recently synthesized the polymorphic compound Sr2Cu(BO3)2 (Smith & Keszler, 1989) which undergoes a first-order phase transition from a low-temperature form to a high-temperature form at 1073 K. The high-temperature beta form exhibits larger coordination numbers for the Sr atoms and a substantial rearrangement of the copper borate network relative to that of the low-temperature... form

An amorphous oxide semiconductor thin-film transistor route to oxide electronics

Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) invented only one decade ago are now being commercialized for active-matrix liquid crystal display (AMLCD) backplane applications. They also appear to be well positioned for other flat-panel display applications such as active-matrix organic light-emitting diode (AMOLED) applications, electrophoretic displays, and transparent displays. The objectives of this contribution are to overview AOS materials design; assess indium gallium zinc oxide (IGZO) TFTs for AMLCD and AMOLED applications; identify several technical topics meriting future scrutiny before they can be confidently relied upon as providing a solid scientific foundation for underpinning AOS TFT technology; and briefly speculate on the future of AOS TFTs for display and non-display applications

Inverse Design of High Absorption Thin-Film Photovoltaic Materials

No abstract available.Keywords: Photovoltaics, Chalcogenide semiconductor, Tandem solar cells, Photovoltaic absorber, Thin filmKeywords: Photovoltaics, Chalcogenide semiconductor, Tandem solar cells, Photovoltaic absorber, Thin fil

Solution based prompt inorganic condensation and atomic layer deposition of Al₂O₃ films: A side-by-side comparison

A comparison was made of Al₂O₃ films deposited on Si via prompt inorganic condensation (PIC) and atomic layer deposition (ALD). Current–voltage measurements as a function of annealing temperature indicate that the solution-processed PIC films, annealed at 500°C, exhibit lower leakage and roughly equivalent breakdown strength in comparison to ALD films. PIC films are less dense than as-deposited ALD films and capacitance–voltage measurements indicate a lower relative dielectric constant. On the basis of x-ray photoelectron spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy, it is found that the 500°C anneal results in the formation of a ~6 nm thick interfacial SiO₂ layer at the Si interface. This SiO₂ interfacial layer significantly affects the electrical performance of PIC Al₂O₃ films deposited on Si.This is the publisher’s final pdf. The published article is copyrighted by the American Vacuum Society and can be found at: http://scitation.aip.org/content/avs/journal/jvsta

Barrier height estimation of asymmetric metal-insulator-metal tunneling diodes

See article for Abstract.Article Copyright 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This is the publisher’s final pdf. The published article can be found at: http://scitation.aip.org/content/aip/journal/jap

p-type conductivity in wide-band-gap BaCuQF (Q=S,Se)

BaCuQF (Q=S,Se) materials, candidate transparent p-type conductors, were prepared by solid-state reaction, and their bulk electrical and optical properties were evaluated. The room-temperature Seebeck coefficient and electrical conductivity of undoped BaCuQF pellets were +56 μV/K and 0.088 S/cm, respectively, for the sulfide fluoride, and +32 μV/K and 0.061 S/cm, respectively, for the selenide fluoride. The conductivity was greatly enhanced by the substitution of several percent of K for Ba; the highest conductivities were 82 S/cm for Ba₀.₉K₀.₁CuSF and 43 S/cm for Ba₀.₉K₀.₁SeF. The band gaps for Q=S and Q=Se were measured to be 3.2 and 3.0 eV, respectively. Undoped BaCuSF exhibits strong red luminescence near 630 nm under ultraviolet excitation.Article appears in Applied Physics Letters (http://apl.aip.org/) and is copyrighted by American Institute of Physics (http://www.aip.org/)

STEM Graduate Students’ Development at the Intersection of Research, Leadership, and Innovation

Researcher innovation and leadership skills are fundamental to create implementable solutions to pressing societal- and market-based global problems. The Research to Innovation to Society (R2I2S) program is a transformative approach to graduate education, training students at the intersection of research, innovation, and leadership. We detail the design of the program, and a three-year exploratory investigation of its impact at one research university in the western United States. We found that, overall, students who participated in the program realized the value of thinking about their scientific research from a market-need perspective. Students perceived enhanced interest in and understanding of societal and market insights related to their own and other’s research. As well, students developed professional skills in communication, team collaboration, innovation, and entrepreneurial skills. We situate our findings in frameworks concerning the development of emerging professionals and argue for programming for STEM graduate students that extends the deep discipline knowledge-based model of professional development into one inclusive of leadership, communication, and innovation goals

Alkali metal coactivators in SrS: Cu,F thin-film electroluminescent devices

A unique approach for obtaining bright and efficient saturated green phosphors for alternating-current thin-film electroluminescent (ACTFEL) device applications is presented. The approach involves color-shifting blue SrS:Cu,F ACTFEL phosphors into the green region of the spectrum via the incorporation of alkali metal ions into the SrS lattice. Alkali metals are incorporated into SrS:Cu,F phosphors by using LiF, NaF, KF, RbF, or CsF coactivators. The best result to date is obtained by using a KF coactivator and results in a saturated green brightness and efficiency of 52.7 cd/m² and 0.973 lm/W (at a frequency of 60 Hz and an overvoltage of 40 V). In addition to providing a color shift, the alkali-metal fluorides improve the overall performance of the ACTFEL device by increasing the magnitude of the electric field and its uniformity across the phosphor through suppression of positive space charge

High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer

Transparent thin-film transistors (TTFTs) with an amorphous zinc tin oxide channel layer formed via rf magnetron sputter deposition are demonstrated. Field-effect mobilities of 5–15 and 20–50 cm² V‾¹ s‾¹ are obtained for devices post-deposition annealed at 300 and 600 °C, respectively. TTFTs processed at 300 and 600 °C yield devices with turn-on voltage of 0–15 and −5–5 V, respectively. Under both processing conditions, a drain current on-to-off ratio greater than 10⁷ is obtained. Zinc tin oxide is one example of a new class of high performance TTFT channel materials involving amorphous oxides composed of heavy-metal cations with (n−1)d¹⁰ ns⁰ (n ≥4) electronic configurations