Local-structure origins of the sustained Curie temperature in (Ba,Ca)TiO₃ ferroelectrics

Igor Levin, Victor Krayzman, and Joseph C. Woicik

While the lattice volume in the solid-solution Ba_1−xCaxTiO₃ decreases with increasing x, the Curie temperature remains unaffected, in contrast to Ba_1−xSrxTiO₃. We have determined the origin of this phenomenon by comparing the local structures in (Ba,Ca)TiO₃ and (Ba,Sr)TiO₃.

Appl. Phys. Lett. 102, 162906 (2013) | HTML | PDF

Tunable giant magnetic anisotropy in amorphous SmCo thin films

F. Magnus, R. Moubah, A. H. Roos, A. Kruk, V. Kapaklis, T. Hase, B. Hjörvarsson, and G. Andersson

SmCo thin films have been grown by magnetron sputtering at room temperature with a composition of 2–35 at. % Sm. Films with 5 at. % or higher Sm are amorphous and smooth

Appl. Phys. Lett. 102, 162402 (2013) | HTML | PDF

Improving the intrinsic cut-off frequency of gate-all-around quantum-wire transistors without channel length scaling

A. Benali, F. L. Traversa, G. Albareda, M. Aghoutane, and X. Oriols

Progress in high-frequency transistors is based on reducing electron transit time, either by scaling their lengths or by introducing materials with higher electron mobility. For gate-all-around quantum-wire transistors with lateral dimensions similar or smaller than their length, a careful analysis of the displacement current reveals that a time shorter than the transit time controls their high-frequency performance.

Appl. Phys. Lett. 102, 173506 (2013) | HTML | PDF

Dexterous manipulation of microparticles using Bessel-function acoustic pressure fields

Charles R. P. Courtney, Bruce W. Drinkwater, Christine E. M. Demore, Sandy Cochran, Alon Grinenko, and Paul D. Wilcox

The authors show that Bessel-function acoustic pressure fields can be used to trap and controllably position microparticles. A circular, 16-element ultrasound array generates and manipulates an acoustic field within a chamber, trapping microparticles and agglomerates.

Appl. Phys. Lett. 102, 123508 (2013) | HTML | PDF

Tuning magnetic anisotropy in (001) oriented L1₀ (Fe_1−xCux)₅₅Pt₄₅ films

Dustin A. Gilbert, Liang-Wei Wang, Timothy J. Klemmer, Jan-Ulrich Thiele, Chih-Huang Lai, and Kai Liu

The authors have achieved (001) oriented L10 (Fe_1−xCu_x)₅₅Pt₄₅ thin films, with magnetic anisotropy up to 3.6 × 10⁷ erg/cm³, using atomic-scale multilayer sputtering and post annealing at 400 °C for 10 s. By fixing the Pt concentration, structure and magnetic properties are systematically tuned by the Cu addition.

Appl. Phys. Lett. 102, 132406 (2013) | HTML | PDF

Band alignment in SnS thin-film solar cells: Possible origin of the low conversion efficiency

Lee A. Burton and Aron Walsh

Tin sulfide is an attractive absorber material for low-cost thin-film solar cells. Despite the ideal physical properties of bulk SnS, the photovoltaic conversion efficiencies achieved in devices to date have been no greater than 2%.

Appl. Phys. Lett. 102, 132111 (2013) | HTML | PDF

Planar junctionless transistor with non-uniform channel doping

Partha Mondal, Bahniman Ghosh, and Punyasloka Bal

The authors propose a planar junctionless transistor (JLT) in silicon-on-insulator (SOI) with non-uniform channel doping in vertical direction to improve the ON to OFF drain current ratio. In single gate JLT in SOI, a thin device layer is depleted in the off-state from the top of the layer and the leakage current flows through bottom of the device layer, and the leakage current depends on the device layer thickness.

Appl. Phys. Lett. 102, 133505 (2013) | HTML | PDF

Study of gate oxide traps in HfO₂/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by use of ac transconductance method

X. Sun, O. I. Saadat, K. S. Chang-Liao, T. Palacios, S. Cui, and T. P. Ma

The authors introduce an ac-transconductance method to profile the gate oxide traps in a HfO₂ gated AlGaN/GaN Metal-Oxide-Semiconductor High-Electron-Mobility Transistors (MOS-HEMTs) that can exchange carriers with metal gates, which in turn causes changes in analog and pulsed channel currents. The method extracts energy and spacial distributions of the oxide and interface traps under the gate from the frequency dependence of ac transconductance.

Appl. Phys. Lett. 102, 103504 (2013) | HTML | PDF

Effect of the magnetic order on the room-temperature band-gap of Mn-doped ZnO thin films

X. L. Wang, C. Y. Luan, Q. Shao, A. Pruna, C. W. Leung, R. Lortz, J. A. Zapien, and A. Ruotolo

Exchange interaction between localized magnetic moments mediated by free charge carriers is responsible for a non-monotonic dependence of the low-temperature energy band-gap in dilute magnetic semiconductors. The authors found that in weakly doped Mn-ZnO films, increasing the exchange interaction by increasing the concentration of free charge carriers results in a red-shift of the near-band-edge emission peak at room temperature.

Appl. Phys. Lett. 102, 102112 (2013) | HTML | PDF

Electric-field control of the magnetic anisotropy in an ultrathin (Ga,Mn)As/(Ga,Mn)(As,P) bilayer

T. Niazi, M. Cormier, D. Lucot, L. Largeau, V. Jeudy, J. Cibert, and A. Lemaître

The authors report on the electric control of the magnetic anisotropy in an ultrathin ferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer with competing in-plane and out-of-plane anisotropies. The carrier distribution and therefore the strength of the effective anisotropy are controlled by the gate voltage of a field effect device.

Appl. Phys. Lett. 102, 122403 (2013) | HTML | PDF