Three-dimensional current collapse imaging of AlGaN/GaN high electron mobility transistors by electric field-induced optical second-harmonic generation
Three-dimensional(3D) current collapse imaging of Schottky gate AlGaN/GaNhigh electron mobility transistor devices was achieved by a combination of two-dimensional (2D) and depth directional electric field-induced optical second-harmonic generation (EFISHG) measurements. EFISHG can detect the electric field produced by trapped carriers, which causes the current collapse. In the 2D measurement, the strong second-harmonic (SH) signals appeared within 1 μm from the gate edge on the drain side at 0.8 μs after the transition from the off- to no bias- state in both unpassivated and passivated samples. In the depth measur...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Takashi Katsuno, Takaaki Manaka, Tsuyoshi Ishikawa, Narumasa Soejima, Tsutomu Uesugi and Mitsumasa Iwamoto Source Type: research
Wireless actuation with functional acoustic surfaces
Miniaturization calls for micro-actuators that can be powered wirelessly and addressed individually. Here, we develop functional surfaces consisting of arrays of acousticallyresonant micro-cavities, and we demonstrate their application as two-dimensional wireless actuators. When remotely powered by an acoustic field, the surfaces provide highly directional propulsive forces in fluids throughacoustic streaming. A maximal force of ∼0.45 mN ismeasured on a 4 × 4 mm2 functional surface. The response of the surfaces with bubbles of different sizes is characterized experimentally. This shows a marked peak around the ...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: T. Qiu, S. Palagi, A. G. Mark, K. Melde, F. Adams and P. Fischer Source Type: research
Asymmetric plasmon structures on ZnO: Ga for high sensitivity in the infrared range
This paper presentssurface plasmons (SPs) onZnO: Ga layers using an asymmetric insulator-metal-insulator (IMI) geometry. The water-ZnO: Ga-cytop tri-layers comprising IMIstructures showed narrowersurface plasmon resonancespectra than insulator-metalstructures with water-ZnO: Ga single layers. Measurements of bulk sensitivities based onrefractive index changes revealed extended evanescent fields on theZnO: Ga layersurfaces when using reduced layer thicknesses. Consequently, the asymmetric IMI geometry onZnO: Ga provides enhanced sensitivity in the infrared range. This result is further discussed from theoretical analyses of...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Hiroaki Matsui, Akifumi Ikehata and Hitoshi Tabata Source Type: research
Enhanced random lasing from distributed Bragg reflector assisted Au-ZnO nanowire Schottky diode
An electrically pumped ultravioletrandom laser based on an Au-ZnOnanowireSchottky junction on top of a SiO2/SiNxdistributed Bragg reflector(DBR) has been fabricated. Electrical characterization shows typicalSchottky diode current-voltage characteristics. Evident random lasing behavior is observed from electroluminescence measurement at room temperature. In comparison with a reference device having similarnanowire morphology but noDBR, this laser demonstrates almost 1.8 times reduction in threshold current and 4 times enhancement in output power. The performance enhancement originates from the incorporation of theDBR struct...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Sunayna B. Bashar, Mohammad Suja, Wenhao Shi and Jianlin Liu Source Type: research
Visualization of deep ultraviolet photons based on F örster resonance energy transfer and cascade photon reabsorption in diphenylalanine-carbon nitrides composite film
A diphenylalanine (L-Phe-L-Phe, FF)-carbon nitride composite film is designed and fabricated to visualize the deepultraviolet (DUV, 245 –290 nm)photons. The FF film, composed of diphenylalanine molecules, doped withcarbon nitrides shows blue emission under excitation of DUV light, which makes the DUV beam observable. Both F örster resonanceenergy transfer and cascadephoton reabsorption contribute to the conversion ofphotonenergy. First, the FF is excited by the DUVphotons. On one hand, theenergy transfers to the embeddedcarbon nitrides through nonradiative dipole –dipole couplings. On the other hand, the 284 nmpho...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Zhixing Gan, Weiping Zhou, Zhihui Chen, Huan Wang, Yunsong Di and Shisong Huang Source Type: research
Soft tunable diffractive optics with multifunctional transparent electrodes enabling integrated actuation
We present a stretchable tunable transmissiongrating in which the optical surface serves simultaneously as anelectrode forelectrostatic actuation. Tunableoptics based onelastomers allow for a large tuning range, but integrating an actuator generally significantly increases the device footprint. By combining the optical and electrical functions into one multifunctional transparentmaterial, we use here thegrating as an integral part of adielectricelastomer actuator and hence avoid placing actuators around thegrating. The grating/electrode consists of a 750 nm thick soft ionogel, which is bonded on both sides of a 13 μm...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Xiaobin Ji, Samuel Rosset and Herbert R. Shea Source Type: research
An InN/InGaN/GaN nanowire array guided wave photodiode on silicon
The III-nitridenanowireheterostructure arrays with multiple InN disk light absorbing regions have beengrown by plasma-assisted molecular beam epitaxy on (001)Si substrates, andguided wavephotodiodes have beenfabricated and characterized. Thespectralphotocurrent of the devices has been measured under reverse bias, and the data exhibit distinct shoulders in the range of 0.69 –3.2 eV (0.39–1.8 μm). The estimated responsivity at a wavelength of 1.3 μm is 0.2 A/W. Thenanowirephotodiode response was also measured with an excitation at one facet provided by an edge-emitting laserfabricated with the samenanowire array...
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: Arnab Hazari, Md. Zunaid Baten, Lifan Yan, Joanna M. Millunchick and Pallab Bhattacharya Source Type: research
Pauli blockade in a few-hole PMOS double quantum dot limited by spin-orbit interaction
We report on the hole compact doublequantum dots fabricated using a conventional CMOS technology. We provide the evidence of Pauli spin blockade in the few hole regime that is relevant to spinqubit implementations. Acurrent dip is observed around zeromagnetic field, in agreement with the expected behavior for the case of strong spin-orbit. We deduce an intradotspin relaxation rate≈120 kHz for the first holes, an important step towards a robust hole spin-orbitqubit. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: H. Bohuslavskyi, D. Kotekar-Patil, R. Maurand, A. Corna, S. Barraud, L. Bourdet, L. Hutin, Y.-M. Niquet, X. Jehl, S. De Franceschi, M. Vinet and M. Sanquer Source Type: research
Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser
We demonstrate the feasibility of high-resolution terahertz gasspectroscopy based on the externaloptical feedback effect in a quantum-cascade laser. Tuning the frequency of the quantum-cascade laser across a molecularabsorption line of CH3OH leads to a reduction of theoptical feedback, which can be detected by monitoring the voltage across the quantum-cascade laser. This method provides a highspectral resolution ofν/Δν=106 and a sensitivity comparable to that obtained with a cryogenically cooled Ge:Ga photoconductive detector. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn and H.-W. H übers Source Type: research
Engineering interface-type resistance switching based on forming current compliance in ITO/Ga2O3:ITO/TiN resistance random access memory: Conduction mechanisms, temperature effects, and electrode influence
In this paper, an ITO/Ga2O3:ITO/TiN structuredresistance random access memory is introduced. Either interface or filamentconduction mechanism can be induced depending on the forming compliancecurrent, which has not been investigated before. Material analyses and electrical I –V measurements on this ITO/Ga2O3:ITO/TiN have also been carried out. The interfaceconduction mechanism was confirmed by a size-effect experiment, whereresistance varied inversely to via size. In addition, thecurrent fitting results show thatSchottky emission dominates the on- and off-statecurrents. All physical mechanisms of deviceresistive switchin...
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: Chih-Hung Pan, Ting-Chang Chang, Tsung-Ming Tsai, Kuan-Chang Chang, Po-Hsun Chen, Shi-Wang Chang-Chien, Min-Chen Chen, Hui-Chun Huang, Huaqiang Wu, Ning Deng, He Qian and Simon M. Sze Source Type: research
3D scanning Hall probe microscopy with 700 nm resolution
In this report, we present athree dimensional(3D) imaging ofmagnetic field vectorB→(x,y,z) emanating from the magnetic material surfaces using a scanning Hall probemicroscopy(3D-SHPM) down to a 700 nmspatial resolution. The Hall probe is used tomeasureBz(x,y) on the specimen surface at different heights with the step size of Δz = 250 nm, as we move away from the surface in z direction, until the field decays to zero. These set of images are then used to get∂Bz(x,y)/∂x and∂Bz(x,y)/∂y at differentz by numerical differentiation. Using theMaxwell's equations in the source free region,Bx(x,y) andBy(x,y) ca...
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: M. Dede, R. Akram and A. Oral Source Type: research
Electrical detection of magnetization dynamics in an ultrathin CoFeB film with perpendicular anisotropy
The anomalous Hall effect (AHE) was used to investigate the magnetization dynamics of an ultrathin (1.3 nm) CoFeB magnetic multilayer with perpendicularmagnetic anisotropy (PMA). By directly sending a radio frequency (rf)current into a millimeter-sizedfilm sample without any lithography process, aresonantdc voltage can be detected along the Hall direction. This method was used to study the dynamic properties of ultrathin CoFeBfilms, such as the gyromagnetic ratio, amplitude of PMA field, and magnetic damping. Thedc voltage was proven to be the consequence of spinrectification enabled by the AHE, and the dynamic magnetiz...
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: Wenwen Kong, Xiaolong Fan, Hengan Zhou, Jiangwei Cao, Dangwei Guo, Y. S. Gui, C.-M. Hu and Desheng Xue Source Type: research
Highly-mismatched InAs/InSe heterojunction diodes
We report onheterojunction diodes prepared by exfoliation and direct mechanical transfer of ap-type InSe thin film onto ann-typeInAs epilayer. We show that despite the differentcrystal structures and large lattice mismatch ( ∼34%) of the component layers, thejunctions exhibitrectification behaviour withrectification ratios of ∼104 at room temperature and broad-band photoresponse in the near infrared and visiblespectral ranges. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: A. V. Velichko, Z. R. Kudrynskyi, D. M. Di Paola, O. Makarovsky, M. Kesaria, A. Krier, I. C. Sandall, C. H. Tan, Z. D. Kovalyuk and A. Patan è Source Type: research
Early stages of irradiation induced dislocations in urania
The early stages ofnucleation and growth ofdislocations byirradiation in urania is clarified based on the combination of experiments and atomistic calculations. It is established thatirradiation induceddislocations follow a five stage process: (i) point defects are first created byirradiation, (ii) they aggregate into clusters, (iii) from which nucleate Frank loops, (iv) which transform into unfaulted loops via Shockley that in turn grow, and (v) finally reorganize into forestdislocations. Stages (i) –(iii) participate in the lattice expansion while the onset of lattice contraction starts with stage (iv), i.e., when unfa...
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: A. Chartier, C. Onofri, L. Van Brutzel, C. Sabathier, O. Dorosh and J. Jagielski Source Type: research
Dominance of radiative recombination from electron-beam-pumped deep-UV AlGaN multi-quantum-well heterostructures
AlGaN-basedmultiple-quantum-well(MQW)heterostructures were irradiated with a pulsedelectron beam. Excitation with abeam energy of12 keV and abeam current of4.4 mA produced cathodoluminescense atλ=246 nm with ameasured peak output power of>200 mW. The emission is dominated by radiative recombination from theMQW up to the maximum tested excitation power density of1 MW/cm2, as evidenced by unity slope in a double-logarithmic plot of the light output power vs. excitation power density.Monte Carlo simulations of the depth distribution of deposited energy for differentbeam energies produced good agreement with themeas...
Source: Applied Physics Letters - November 4, 2016 Category: Physics Authors: Farsane Tabataba-Vakili, Thomas Wunderer, Michael Kneissl, Zhihong Yang, Mark Teepe, Max Batres, Martin Feneberg, Bernard Vancil and Noble M. Johnson Source Type: research
