Fabrication of a nanometer thick nitrogen delta doped layer at the sub-surface region of (100) diamond
In this letter, we report on the proof of a concept of an innovative deltadoping technique to fabricate an ensemble of nitrogen vacancy centers at shallow depths in (100)diamond. A nitrogen deltadoped layer with a concentration of ∼1.8 × 1020 cm−3 and a thickness of a few nanometers was produced using this method. Nitrogen deltadoping was realized by producing a stable nitrogen terminated (N-terminated)diamond surface using the RFnitridation process and subsequently depositing a thin layer ofdiamond on the N-terminateddiamond surface. The concentration of nitrogen on the N-terminateddiamond surface and its stabili...
Source: Applied Physics Letters - December 2, 2016 Category: Physics Authors: Maneesh Chandran, Shaul Michaelson, Cecile Saguy and Alon Hoffman Source Type: research
Heterogeneously integrated III –V-on-silicon 2.3x μm distributed feedback lasers based on a type-II active region
We report on 2.3xμm wavelength InP-based type-II distributed feedback(DFB) lasers heterogeneously integrated on asiliconphotonics integrated circuit. In the devices, a III –Vepitaxial layer stack with a “W”-shaped InGaAs/GaAsSb multi-quantum-well active region is adhesively bonded to the first-ordersiliconDFBgratings. Single mode laser emission coupled to a single modesiliconwaveguide with a side mode suppression ratio of 40 dB is obtained. In continuous-wave regime, the 2.32 μm laser operates close to room temperature (above 15 °C) and emits more than 1 mW output power with a threshold current density of ...
Source: Applied Physics Letters - December 2, 2016 Category: Physics Authors: Ruijun Wang, Stephan Sprengel, Aditya Malik, Anton Vasiliev, Gerhard Boehm, Roel Baets, Markus-Christian Amann and Gunther Roelkens Source Type: research
Use of optoelectronic tweezers in manufacturing —accurate solder bead positioning
In this work, we analyze the use of optoelectronic tweezers(OETs) to manipulate 45 μm diameter Sn62Pb36Ag2 solder beads with light-induceddielectrophoresis force and we demonstrate high positioning accuracy. It was found that the positional deviation of the solder beads increases with the increase of the trap size. To clarify the underlying mechanism, simulations based on the integration of the Maxwell stress tensor were used to study the force profiles ofOET traps with different sizes. It was found that the solder beads felt a 0.1 nN staticfriction or stiction force due to electrical forces pulling them towards the su...
Source: Applied Physics Letters - December 2, 2016 Category: Physics Authors: Shuailong Zhang, Yongpeng Liu, Joan Juvert, Pengfei Tian, Jean-Claude Navarro, Jonathan M. Cooper and Steven L. Neale Source Type: research
Direct fabrication of compound-eye microlens array on curved surfaces by a facile femtosecond laser enhanced wet etching process
We report a directfabrication of an omnidirectional negative microlens array on a curved substrate by afemtosecond laser enhanced chemicaletching process, which is utilized as a molding template for duplicating bioinspired compoundeyes. Thefemtosecond laser treatment of the curvedglass substrate employs a commonx-y-z stage without rotating the sample surface perpendicular to thelaser beam, and uniform, omnidirectional-aligned negativemicrolenses are generated after a hydrofluoric acidetching. Using the negative microlens array on the concaveglass substrate as a molding template, wefabricate an artificial compoundeye with 3...
Source: Applied Physics Letters - December 2, 2016 Category: Physics Authors: Hao Bian, Yang Wei, Qing Yang, Feng Chen, Fan Zhang, Guangqing Du, Jiale Yong and Xun Hou Source Type: research
An integrated mirror and surface ion trap with a tunable trap location
We report a demonstration of a surfaceion trap fabricated directly on a highly reflectivemirror surface, which includes a secondary set of radio frequency (RF)electrodes allowing for translation of the quadrupole RF null location. We introduce a position-dependent photon scattering rate for a174Yb+ ion in the direction perpendicular to the trap surface using a standing wave of retroreflected light off themirror surface directly below the trap. Using this setup, we demonstrate the capability of fine-tuning the RF trap location with nanometer scale precision and characterize the charging effects of thedielectricmirror surfac...
Source: Applied Physics Letters - December 2, 2016 Category: Physics Authors: Andre Van Rynbach, Peter Maunz and Jungsang Kim Source Type: research
Wireless power transfer based on dielectric resonators with colossal permittivity
Magneticresonant wireless power transfer system based ondielectric diskresonators made of colossalpermittivity (ε = 1000) and low loss (tan δ = 2.5 × 10–4)microwaveceramic is experimentally investigated. The system operates at the magnetic dipole mode excited in theresonators providing maximal power transfer efficiency of 90% at the frequency 232 MHz. By applying an impedance matching technique, the efficiency of 50% is achieved within the separation between theresonatorsd = 16 cm (3.8 radii of theresonator). The separation, misalignment and rotation dependencies of wireless power transfer effic...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Mingzhao Song, Pavel Belov and Polina Kapitanova Source Type: research
Reaping the benefits of ferroelectricity in selectively precipitated lithium niobate microcrystals in silica matrix for photocatalysis
Microcrystals of LiNbO3 (size ∼200 nm) can be selectively precipitated in aglass matrix which can assist in the photocatalytic activity through ferroelectricity.Glass with the composition 30SiO2-35Li2CO3-35Nb2O5 was utilized for the process. A remarkably high Estriol (E3) degradation rate of 232.54 min−1 m−2 was obtained. The degradation was monitored usingfluorescence spectroscopy with a detection limit in nanomolar (nM) range. From the fitting offluorescence intensity versus time, it was observed that degradation of estriol follows a pseudo first-order reaction kinetics. The results indicate that LiNbO3 base...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Monisha Rastogi, Aditya Chauhan, Himmat Singh Kushwaha, Ramachandran Vasant Kumar and Rahul Vaish Source Type: research
Imaging photocurrent collection losses in solar cells
A method is proposed that enables the imaging of thephotocurrent collected by a solar cell under arbitrary operating conditions. The method uses a series of luminescence images under varyingillumination to derive the totalphotocurrent collection efficiency at a given voltage bias. The resulting totalphotocurrent collection image directly relates to the difference between the dark and illuminated current-voltagecharacteristics of the cell. A crystallinesilicon solar cell is used to test the method, and the images of the totalphotocurrent collection efficiency are used to quantify the influence of a crack on the total collec...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Vito Huhn, Bart E. Pieters, Yael Augarten, Andreas Gerber, David Hinken and Uwe Rau Source Type: research
Memory operations in Au nanoparticle single-electron transistors with floating gate electrodes
Floating gate memory operations are demonstrated in a single-electron transistor (SET) fabricated by a chemical assembly using theAu nanogapelectrodes and the chemisorbedAunanoparticles. By applying pulse voltages to the control gate, phase shifts were clearly and stably observed both in the Coulomb oscillations and in the Coulombdiamonds. Writing and erasing operations on the floating gate memory were reproducibly observed, and thecharges on the floating gateelectrodes were maintained for at least 12 h. By considering thecapacitance of the floating gateelectrode, the number ofelectrons in the floating gateelectrode was...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Yasuo Azuma, Masanori Sakamoto, Toshiharu Teranishi and Yutaka Majima Source Type: research
Significant enhancement of the charging efficiency in the cavities of ferroelectrets through gas exchange during charging
Ferroelectrets are non-polarpolymer foams orpolymer systems with internallycharged cavities. They arecharged through a series ofdielectric barrier discharges (DBDs) that are caused by the electrical breakdown of the gas inside the cavities. Thus, the breakdown strength of the gas strongly influences thecharging process of ferroelectrets. A gas with a lower breakdown strength has a lower threshold voltage, thus decreasing the onset voltage for DBDcharging. However, a lower threshold voltage also leads to a lower value for the remanentpolarization, as back discharges that are caused by theelectric field of the internally dep...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Xunlin Qiu Source Type: research
Electrical characteristics of MoSe2 TFTs dependent on the Al2O3 capping layer
Back-gated MoSe2thin-film transistors(TFTs) with an Al2O3-capping layer were fabricated, and the devicecharacteristics of the MoSe2TFTs that are dependent on the Al2O3-capping-layerpassivation were investigated. The output drain current was doubled, the fluctuation of the output current was suppressed, and the threshold voltage of the MoSe2TFTs was negatively shifted with the Al2O3-capping layer. The on/off-current ratio of the MoSe2TFTs is approximately six decades regardless of the Al2O3-capping layer, but the field-effect mobility was greatly increased from 2.86 cm2/Vs to 10.26 cm2/Vs after thedeposition of the Al...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Hyunjea Lee, Ji Heon Kim and Cheol Jin Lee Source Type: research
A post-fabrication selective magnetic annealing technique in standard MEMS processes
A selective electrothermalmagnetic annealing technique is introduced that provides programming capabilities for mechanical micro-resonators. In the proposed approach, the magneticproperties ofresonators can be locally tuned in a post-fabrication batch-compatible process step. A prototype is implemented in a standard microfabrication process, where resonatingferromagnetic elements are suspended on top of a polysilicon resistiveheater. Theferromagnetic elements consist of electroplated Nickel (Ni) with minor Iron (Fe) impurities. The electro-thermo-mechanical heating phenomenon is simulated for design purposes. Themagnetizat...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: A. Mohammadi, N. C. Karmakar and M. R. Yuce Source Type: research
Resonant response in mechanically tunable metasurface based on crossed metallic gratings with controllable crossing angle
We report on a modern class of mechanically tunable planarmetamaterials comprisingresonating units formed by crossed metallic stripgratings. We observe aresonant response in transmissionspectra of a linearly polarized wave passing through a system of crossedgratings in themicrowave regime. Eachgrating consists of an array of parallel metallic strips located on the top of adielectric substrate. It is revealed that theresonant position appears to be dependent on the angle of crossedgratings. It is found theoretically and experimentally that theresonant shift on the frequency scale appears as a result of increasing in the len...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: V. Yachin, L. Ivzhenko, S. Polevoy and S. Tarapov Source Type: research
Self-assembled dual-sided hemispherical nano-dimple-structured broadband antireflection coatings
A non-lithography-based approach is developed in this study for assembling monolayer close-packed hemispherical nano-dimple arrays on both sides of a PET film by a scalable Langmuir-Blodgett technology. The resulting gratings greatly suppress specular reflection and therefore enhance specular transmission for a broad range of visible wavelengths, resulting from a gradual change in the effectiverefractive index at air/PET interface. The experimental results reveal that the antireflection properties of the as-fabricated coatings are affected by the size of the nano-dimples. Moreover, both optical performances of single-sided...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Cheng-Yen Lin, Kun-Yi Lin, Hui-Ping Tsai, Yi-Xuan He and Hongta Yang Source Type: research
Dispersion in a broadband terahertz quantum cascade laser
We presentdispersion data of a broadband terahertzquantum cascade laser with a heterogeneous active region. The experimental method to extract the group velocitydispersion of the entirelaser cavity, including the contributions of the active region, the semiconductor material, and the waveguide relies on a time-domain spectroscopy system. The obtained group velocitydispersion curves exhibit oscillations with amplitudes up to 1 × 105 fs2/mm between 2.0 and 3.0 THz and strongly depend on the driving conditions of the laser. This indicates that the group velocitydispersion is mainly determined by the intersubband ga...
Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Dominic Bachmann, Markus R ösch, Giacomo Scalari, Mattias Beck, Jérôme Faist, Karl Unterrainer and Juraj Darmo Source Type: research
