High voltage breakdown (1.8 kV) of hydrogenated black diamond field effect transistor
We fabricated and characterized blackpolycrystallinediamondfield effect transistors. By implementing a C-H bonded channel with a wide gate-drain length up to 20 μm, a breakdown voltage of 1.8 kV was achieved, which is the highest value reported for adiamondfield effect transistor(FET) to date. Several of our devices achieved a breakdown voltage/wide gate-drain length ratio> 100 V/μm. This is comparable to the performance of lateral SiC and GaNFETs. We investigated the effects of voltage stress up to 2.0 kV, and showed that the maximumcurrent density fell to 26% of its initial value of 2.42 mA/mm before th...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: M. Syamsul, Y. Kitabayashi, D. Matsumura, T. Saito, Y. Shintani and H. Kawarada Source Type: research
Zero dark leakage current single-walled carbon nanotube diodes
We describemeasurements of diodeleakage currents in p-n and p-i-n diodes formed along individualsingle-walled carbon nanotubes(SWNTs) in the ranges well below the direct detection limit. When cooled, these diodes exhibitleakage currents down in the range of 10−25 A or equivalent to 1 electron/19 days. To verify ourmeasurement of such lowleakage currents, we use thephotovoltaic property under varying temperatures to extract the dark diodeleakage currents. Sincenanotubes are sensitive in the near IR spectrum, these diodes show promise as zero dark currentnoise, near-infrared detectors. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Prathamesh Dhakras and Ji Ung Lee Source Type: research
Possible n/p-type conductivity of two-dimensional graphene oxide by boron and nitrogen doping: Evaluated via constrained excitation
As thefirst-principles calculations using the supercell approximation give widely scattered results in a two-dimensional charged system, making the evaluation of defectionization energy difficult, here an alternative constrained excitation is applied to overcome this problem for defect analysis. As an example ingraphene oxide with 50% oxygen coverage (according to the popular epoxy-chain-plus-hydroxyl-chain model), the structures, stabilities, and electronic properties of nitrogen andborondopants are investigated. Generally,boron prefers to replacecarbon in thesp3 region as an acceptor while nitrogen has a tendency to subs...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Dan Wang, Dong Han, Xian-Bin Li, Sheng-Yi Xie, Nian-Ke Chen, Wei Quan Tian, Shengbai Zhang and Hong-Bo Sun Source Type: research
Power conversion efficiency and resistance tunability in coil-magnetoelectric gyrators
The power efficiency andresistance tunability of magnetoelectric (ME) gyrators consisting of two-phase magnetostrictive-piezoelectric ME longitudinal-transverse (L-T) mode sandwichlaminates andcoils, have been studied. The copper wirecoil provided an inductance-basedcoil port (CoilP) and the piezoelectric layer of the MElaminate provided a capacitance-based ME port (MEP). The device behaved as a 2-port 4-wire ME gyrator. The current-to-voltage and voltage-to-current (I-V andV-I, respectively) conversion ratios,resistance-inductance/capacitance tunabilities (TR-L andTR-C, respectively) and direct/converse power efficiencies...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Chung Ming Leung, Xin Zhuang, Junran Xu, G. Srinivasan, Jiefang Li and D. Viehland Source Type: research
Optimized electrocaloric effect by field reversal: Analytical model
This study signifies the importance of considering irreversible process in the electrocaloric cycles. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Yang-Bin Ma, Nikola Novak, Karsten Albe and Bai-Xiang Xu Source Type: research
Interfacial SiO2 scavenging kinetics in HfO2 gate stack
In this paper, Si and oxygendiffusions as well as SiO2 reductionreaction in HfO2/SiO2/Si stacks are examined in detail for fully understanding the SiO2-IL scavenging process. A29Siisotope tracing experiment confirms that Si in SiO2-IL is mostly emitted from the HfO2 surface. In addition, thereaction of oxygen from SiO2 with VO in HfO2 is suggested. Furthermore, it is reported that the Si substrate is not changed at all in the SiO2-IL scavenging by simultaneously comparing a Si surface between with and without scavenged parts. Based on these results, a kineticmodel for the SiO2-IL scavenging in HfO2/SiO2/Si stacks is propos...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Xiuyan Li, Tomonori Nishimura and Akira Toriumi Source Type: research
Doubling the critical current density in superconducting FeSe0.5Te0.5 thin films by low temperature oxygen annealing
Iron chalcogenidesuperconducting thin films and coatedconductors are attractive for potential high field applications at liquid helium temperature for their high critical current densitiesJc, low anisotropies, and relatively strong grain couplings. Embedding flux pinning defects is a general approach to increase the in-field performance ofsuperconductors. However, many effective pinning defects can adversely affect the zero field or self-fieldJc, particularly in cuprate high temperaturesuperconductors. Here, we report the doubling of the self-fieldJc in FeSe0.5Te0.5films by low temperature oxygenannealing, reaching ∼3 MA...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Cheng Zhang, Weidong Si and Qiang Li Source Type: research
Magnetization reversal in ferromagnetic spirals via domain wall motion
We present a combination of analytic and simulated results describing the reliable field driven motion of adomain wall through the arms of aferromagnetic spiralnanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circularwires.Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of thedomain wall, impacting the magnetoresistive applications dependent on thedomain wall location. The spirals' magnetization components are found to depend on the spiral parameters: the initial radius and spacing between spiral arms, along...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Ryan D. Schumm and Andrew Kunz Source Type: research
Ultrafast dynamics in solids probed by femtosecond time-resolved broadband electronic sum frequency generation
Time-resolved sum frequency generation is an established tool to investigate the ultrafast vibrationaldynamics withsurface andinterface specificity, which can be extended to the regime of electronic transitions using a white light continuum as demonstrated previously by studies of liquidinterfaces. We expand this technique to the investigation ofsolid single crystal samples. In particular, we demonstrate the potential of electronic sum frequency generation by probing the non-equilibriumdynamics at excitonic resonances inZnO with a sensitivity as small as 0.6% and with atime resolution of 160 fs. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Laura Foglia, Martin Wolf and Julia St ähler Source Type: research
Symmetry and diffusivity of the interstitial hydrogen shallow-donor center in In2O3
Uniaxial-stress experiments performed for the 3306 cm−1 vibrational line assigned to the interstitial-hydrogen, shallow-donor center in In2O3 reveal its symmetry and transition-moment direction. The defect alignment that can be produced by a [001] stress applied at 165 K is due to a process that is also a hydrogen-diffusion jump, providing a microscopic determination of thediffusion constant for H in In2O3 and its mechanism. Our experimental results strongly complement the theoretical predictions for the structure anddiffusion of theinterstitial hydrogen donor center in In2O3. (Source: Applied Physics Letters)
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Philip Weiser, Ying Qin, Weikai Yin, Michael Stavola, W. Beall Fowler and Lynn A. Boatner Source Type: research
Analysis of polarization speckle for imaging through random birefringent scatterer
Propagation of acoherent light through ananisotropic random medium generates randomly polarized field, known aspolarizationspeckle. In this paper, an experimental technique is proposed and demonstrated to recover the transmittance of a polarized object frompolarizationspeckle. Recovery of the polarized object frompolarizationspeckle is made possible by combining the far-field intensity correlation of the objectspeckle with off-axis holography to determine the complexcoherencefunction of thespeckle. The desired objectspeckle which is uniformly polarized is filtered from thepolarizationspeckle using apolarizer. The results a...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Abhijit Roy, Rakesh K. Singh and Maruthi M. Brundavanam Source Type: research
Photodetection in p –n junctions formed by electrolyte-gated transistors of two-dimensional crystals
Transition metal dichalcogenidemonolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case ofphotoelectric conversion devices such as photodetectors and photovoltaic cells, p –njunctions are one of the most important devices. Here, we demonstrate photodetection with WSe2monolayer films. We prepare the electrolyte-gated ambipolartransistors and electrostatic p –njunctions are formed by the electrolyte-gating technique at 270 K. Thesep-n j...
Source: Applied Physics Letters - November 16, 2016 Category: Physics Authors: Daichi Kozawa, Jiang Pu, Ryo Shimizu, Shota Kimura, Ming-Hui Chiu, Keiichiro Matsuki, Yoshifumi Wada, Tomo Sakanoue, Yoshihiro Iwasa, Lain-Jong Li and Taishi Takenobu Source Type: research
Band slope in CdS layer of ZnO:Ga/CdS/Cu2ZnSnS4 photovoltaic cells revealed by hard X-ray photoelectron spectroscopy
For compoundsemiconductorphotovoltaic cells with a common structure of the window-layer (WL)/buffer-layer (BL)/absorbing-layer (AL), the band slope in BLs, affecting the conversion efficiency, was directly and non-destructively measured byhard X-rayphotoelectron spectroscopy. We demonstrated that the band slope in CdS-BLs sandwiched between WLs and Cu2ZnSnS4 (CZTS)-ALs reflected the trend of the work functions of WLs (ϕWL). This result implies that the larger downward band slope to the WL can be achieved using a smallerϕWL. The relatively large downward band slope of ∼0.5 eV to the WL was estimated in our ZnO:Ga/CdS/...
Source: Applied Physics Letters - November 15, 2016 Category: Physics Authors: Keita Kataoka, Shin Tajima, Mitsutaro Umehara, Naoko Takahashi, Noritake Isomura, Kosuke Kitazumi and Yasuji Kimoto Source Type: research
Asymmetric backscattering from the hybrid magneto-electric meta particle
The opticaltheorem relates the totalscattering cross-section of a givenstructure with itsforward scattering, but does not impose any restrictions on other directions. Strong backward-forward asymmetry inscattering could be achieved by exploring retarded coupling between particles, exhibiting both electric and magnetic resonances. Here, a hybrid magneto-electric particle (HMEP), consisting of a split ring resonator acting as a magnetic dipole and a wireantenna acting as an electric dipole, is shown to possess asymmetricscattering properties. When illuminated from opposite directions with the same polarization of the electri...
Source: Applied Physics Letters - November 15, 2016 Category: Physics Authors: Vitali Kozlov, Dmitry Filonov, Alexander S. Shalin, Ben Z. Steinberg and Pavel Ginzburg Source Type: research
Above room temperature continuous wave operation of a broad-area quantum-cascade laser
We describe the design and implementation of a broad-area (w ≈ 30 μm) quantum-cascade laser operating in a continuous wave mode up to heat-sink temperatures beyond +100 °C. The room-temperature emission wavelength is 4.6 μm. The temperature gradient in the active region of such a wide laser stripe is essentially perpendicular to theepitaxial layers and the resulting steady-state active region temperature offset scales approximately with the square of the number of cascades. With only 10 cascades in the active region, the threshold electrical power density in the current quantum-cascade laser in the continuo...
Source: Applied Physics Letters - November 15, 2016 Category: Physics Authors: M. P. Semtsiv and W. T. Masselink Source Type: research
