Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session B01: Applications: Materials Focus |
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Sponsoring Units: FIAP Chair: Matthieu Dupre, Univ of California - San Diego Room: LACC 150A |
Monday, March 5, 2018 11:15AM - 11:27AM |
B01.00001: Ultrahigh broad band photoresponse in single Germanium Nanowire photodetectors SHAILI SETT, Arup Raychaudhuri We have investigated photoconductive properties of single Germanium Nanowires (NWs) in the broad spectral range of 300-1100 nm and in the broadband Near Infra-red spectrum. The peak Responsivity (R) reaches ~107A/W at a minimal bias of 2V at λ=850 nm. In NWs with diameter ranging from 30 nm to 90 nm, R lies in the range 105-107A/W. The NWs grown by Vapor-Liquid-Solid mechanism can detect upto ~ 10-15 W, with Detectivity ~1013 cmHz1/2/W. In this report we discuss the likely origin of the ultra large R that may arise from a combination of various physical effects which are (a) Ge/GeO2 interface states which act as “scavengers” of electrons from the photo-generated pairs, leaving the holes free to reach the electrodes, (b) Schottky barrier (~0.2 -0.3 eV) at the metal/NW interface which gets lowered substantially due to carrier diffusion in contact region and (c) photodetector length being small (~few μm), negligible loss of photogenerated carriers due to recombination at defect sites. We have confirmed, from power dependence of the optical gain that there is presence of trap states at the surface region and have estimated the surface trap density ~1013cm-2 s-1 that predominantly lie at the Ge/GeO2 interface. |
Monday, March 5, 2018 11:27AM - 11:39AM |
B01.00002: Integrated and Steerable Vortex Lasers using Bound States in Continuum Babak Bahari, Felipe Vallini, Thomas Lepetit, Ricardo Tellez-Limon, Junhee Park, Ashok Kodigala, Yeshaiahu Fainman, Boubacar Kante Steering the beam of a wave source has been demonstrated using mechanical and non-mechanical techniques. While mechanical techniques are bulky and slow, non-mechanical techniques rely on breaking the symmetry of the refractive index profile either using asymmetric structure or injecting a non-uniform current. In this contribution, we theoretically and experimentally demonstrated a new type of topological steering of light sources in which the phase offset is provided by Floquet-Bloch phase in periodic structure. It was shown that in periodic structures, there exist singular states in the radiation region of the band diagram that exhibit diverging quality factor. Thus light sources can operate at these states with lower power threshold. The existence of these singular states are topologically protected, and their momentum are very sensitive to any small perturbations, which is used to control the steering angle. By uniformly controlling some parameters in the system, such as a physical dimension or injecting current uniformly, the beam of the light source steers. Our experimental demonstrations open new paradigm in the implementation of light steering with applications in data communications, bio imaging and sensing. |
Monday, March 5, 2018 11:39AM - 11:51AM |
B01.00003: Highly Stretchable Label-like Random Laser on Universal Substrates Yu-Ming Liao, Shu-Wei Chang, Wei-Cheng Liao, Shih-Yao Lin, Wei-Ju Lin, Cheng-Han Chang, Hung-I Lin, Ying-Chih Lai, Yang-Fang Chen Random lasers have abundant inherent advantages compared to conventional laser, such as flexibility, size, cost, simple design, and mass production. It has been the hot research topic in recent decades. An integrated random laser label with transferability, flexibility, and temperature sensing is created and demonstrated in this work. The highly stretchable label-type random laser (HSRL) can not only function stably under 100% strain with at least 500 times test but can also be easily transferred on arbitrary substrates irrespective of the material being rigid, flexible, nonplanar, or rough. In addition to features mentioned above, random laser signals can be stimulated and controlled repetitively within human body temperature. This shows great potential that the HSRL can serve as photonics modules for further advanced developments of a variety of applications covering many different fi elds, such as wearable systems, robotic sensors, and stretchable information communications. |
Monday, March 5, 2018 11:51AM - 12:03PM |
B01.00004: Large-area inorganic perovskite quantum dot microdisk microlasers enabled by orthogonal photolithography Chun Hao Lin, Qingji Zeng, Evan Lafalce, Marcus Smith, Shengtao Yu, Youngjun Yoon, Yajing Chang, Zhiqun Lin, Zeev Valy Vardeny, Vladimir Tsukruk Solution-processed all inorganic perovskite quantum dots have attracted great attention due to their facile synthesis and promising optical properties such as high quantum yield, high net optical gain and high absorption cross section. However, the ionic nature of these quantum dots makes them prone to dissolution in common polar solvents, which severely hinder the integration of these QDs into patterned photonic structures using standard lithography processes. Here, we report a novel lithography based patterning approach that incorporates fluorinated polymer resist which provides orthogonality to both polar and non-polar materials, thus enabling the facile fabrication of large-area photonic structures including microdisk laser arrays and multicolor pixels. Optical characterization of these structures includes measuring net optical gain value, lasing threshold and mode activity. Importantly, this novel patterning approach can be universally applied to various type of nanocrystals and act as a significant step to the future development of quantum dot based optoelectronic devices that require high-resolution large-area patterned structures. |
Monday, March 5, 2018 12:03PM - 12:15PM |
B01.00005: Patch antenna microcavity arrays for THz sources Joel Pérez Urquizo, Julien Madéo, Yanko Todorov, Carlo Sirtori, Keshav Dani Terahertz radiation has remained underexplored because of a lack of efficient sources and detectors while covering wide-ranging applications for imaging, security or wireless communications. Novel hybrid structures consisting in antenna-coupled microresonators have shown the possibility of confining THz radiation into subwavelength volumes (< 10-5 λ3), combining enhanced light-matter interaction and antennas to in- or out-couple radiation [1]. We present a study based on finite element simulations of the THz emission from finite arrays of patch-antenna microcavities. Emission properties can be engineered solely with the design parameters of the array. By tuning them, the structure can provide a complete control on the radiative and non-radiative losses of the microresonators, low beam divergence (<FWHM 10°) and high photon extraction efficiencies (> 50%) [2]. We used this design to demonstrate experimentally strong enhancement of spontaneous emission from a quantum cascade active region. Our results pave the way in achieving THz lasers with low divergence, single mode operation and optimized losses. [1] J. Madéo,et.al., Appl.Phys.Lett.109,141103(2016) [2] J. Madéo,et.al J. Infrd Milli Terahz Waves,38:1321-1330(2017) |
Monday, March 5, 2018 12:15PM - 12:27PM |
B01.00006: Spectroscopy of Mie resonances excited from internal source Wanwoo Noh, Matthieu Dupre, Ashok Kodigala, Boubacar Kante Mie theory describes how a spherical dielectric particle scatters electromagnetic waves. Numerical improvements have allowed studying more complicated geometries with the multipole decomposition on the spherical harmonics. Hence, Mie theory is widely applied in theoretical and applied physics to enable novel light manipulation, nonlinear optics, or to design dielectric metamaterials. Recently, the anapole state has brought attention in the community as an interesting singularity. It can be interpreted as a destructive interference in the far field between the fields scattered by the toroidal and electrical dipoles at a given frequency. Such element is therefore transparent to any incoming plane wave. However, things are different if the element is excited in its near field from an internal source. In this work, we experimentally demonstrate a semiconductor laser based on a single cylindrical resonator suspended in air fabricated with a top-down lithography. We study the shift of the Mie resonance as geometrical parameters are varied, and show how it affects the lasing frequency. Our investigation of Mie resonances from an active gain medium would be a rich platform to study nontrivial excitation of a complex field and paves the way to design active devices exploiting Mie theory. |
Monday, March 5, 2018 12:27PM - 12:39PM |
B01.00007: All-oxide NiO-Ga2O3 PN Junction Deposited at Room Temperature: Ga2O3 Thickness Effect on PN Junction Performance and Future Applications. Maria Isabel Pintor Monroy, Bayron L. Murillo-Borjas, Julia Hsu, Manuel A. Quevedo-Lopez PN junctions are the base of any bipolar device, being used as solar cells, radiation detectors, UV detectors, JFETs, etc. However, the lack of a high performance p-type oxide semiconductor currently limits the oxide technology to mostly unipolar devices. We will discuss a semi-transparent all-oxide pn junction deposited at room temperature, which allows its integration in flexible electronics and in applications where transparency is required. Ga2O3 was selected as the n-type oxide due to its wide band gap and semiconductor behavior, for the pn junction use as UV detector and other future applications. Finally, the effect of the Ga2O3 layer thickness in the overall pn junction electrical performance will be evaluated. |
Monday, March 5, 2018 12:39PM - 12:51PM |
B01.00008: Investigation of the optical effect of stable VO2 thin films for smart materials applications Merve Ertas Uslu, Ibrahim Burc Misirlioglu, Kursat Sendur In this study, the metallic vanadium thin film was coated on a p-type silicon substrate by e-beam evaporation and then heat treatment was performed in a controlled gas atmosphere. By this method, our aim was to achieve growth of solid metallic films on single crystal substrates followed by the formation of a thin VO2 thin film with +4 valence value for V and obtain a metal/dielectric bilayer with tunable reflectivity. The composition/oxidation state of the surface, crystal structure of the deposited films were analyzed by XPS, SEM, XRD and ellipsometer techniques respectively. The thermochromic properties of VO2 thin film samples were investigated by carrying out temperature dependent reflection measurements where we observed and analyzed the strong dependence of reflectivity on the incoming radiation energy with the upper VO2 layer acting like a filter of reflection. We observe a clear and large hystereses in the reflection specta during heating and cooling near the transition temperature, indicative of a first order transition in contrast to what one would expect in a clamped film as clamping is often thought to convert the transition into second order. This behavior is discussed in the light of 2-phase coexistence for clamped film structures. |
Monday, March 5, 2018 12:51PM - 1:03PM |
B01.00009: Infrared-to-visible Upconversion in Light Emitting Diodes and Phototransistors YING ZHOU, I-te Chen, Kory Green, Chih-Hao Chang, Shuang Fang Lim Infrared excited and visible emitting upconverting nanoparticles show potential applications in the field of light emitting diodes (LED) and photovoltaics. Despite the fundamental advantages that Upconverting Nanoparticles (UCNPs) have over semiconductor nanoparticles and molecular dyes, they have not been used widely due to their comparatively low brightness and low upconversion efficiency at low pump powers. Existing UCNP devices are based on randomly ordered nanoparticles, which have low external efficiency. The nanoparticles are assembled in a periodic array in order to minimize undesirable scattering and light trapping, thereby increasing the light emission output. We fabricate and characterize a nanoplasmonic upconversion array, including its effect on electric field scattering and enhancement, using our expertise in nanoparticle growth, array nanofabrication, single particle high resolution optical spectroscopy, and finite element modeling. |
Monday, March 5, 2018 1:03PM - 1:15PM |
B01.00010: On chip optical storage at telecom wavelengths using rare earth ions Ioana Craiciu, Jake Rochman, Evan Miyazono, John Bartholomew, Chuting Wang, Jonathan Kindem, Tian Zhong, Andrei Faraon Nanophotonic quantum memories are a promising technology with applications in long distance quantum communication. Our work focuses on nanophotonic resonators coupled to ensembles of erbium ions in yttrium orthosilicate crystals (Er:YSO). These devices operate at telecom wavelengths, allowing for integration with silicon photonics and with existing telecommunications technology. We present fixed time optical storage in a nanobeam in isotopically purified Er:YSO using the atomic frequency comb protocol. We further describe our recent efforts to evanescently couple silicon photonic resonators to Er:YSO, with a focus on design improvements to optimize the cavity ion interaction. |
Monday, March 5, 2018 1:15PM - 1:27PM |
B01.00011: Broadband power filters based on Bragg mirrors with alternating phase change material Nicholas Antonellis, Roney Thomas, Tsampikos Kottos We explore the transport properties of a composite periodic photonic structure consisting of two Bragg mirrors with layers of the same optical length but different material. Specifically, we assume that the second mirror involves alternating layers made of a phase change material (PCM). When the incident electromagnetic radiation is low the two Bragg mirrors share the same pass-band characteristics and thus the whole structure demonstrates the same transport properties as the ones associated with the individual mirrors. When, however, the incident electromagnetic radiation is above some critical value, the permittivity of the PCM layers change considerably leading to a shift of the pass-bands of the second mirror. As a result, we observe the development of multiple gaps inside the pass-bands of the initial composite structure. This self-induced broad band suppression of transport in the case of high power EM waves might be useful for the realization of broad-band power filters. |
Monday, March 5, 2018 1:27PM - 1:39PM |
B01.00012: Optically controlled radiative transfer in the near field Junlong Kou, Austin Minnich Actively controlling the heat flow is of great importance for applications of cooling, heating, and energy conversion. It is extremely difficult to achieve high contrast heat flow without moving parts. Here, we propose a thermal modulation scheme based on optical pumping of semiconductors in near-field radiative contact. External photoexcitation of one semiconductor leads to changes in carrier concentration that in turn alters the plasma frequency of silicon, leading to drastic modulation of near field thermal radiation. Calculations based on fluctuational electrodynamics show that the heat transfer coefficient can be tuned from ~ 10 W m-2 K-1 to ~200 W m-2 K-1 with a gap distance of 100 nm at room temperature. |
Monday, March 5, 2018 1:39PM - 1:51PM |
B01.00013: Reflective Volume Bragg Grating with Transverse Chirp Sergiy Mokhov Reflective uniform volume Bragg gratings are used as narrow-band output couplers in high-power lasers with different gain media. VBGs with a longitudinally chirped grating period are used for stretching and compression of short laser pulses in chirped pulse amplification schemes. Here we study transversely chirped volume Bragg gratings (TCVBGs) with uniform refractive index modulation along the longitudinal direction of reflection at any particular transverse point of incidence. While modeling of laser cavity utilizing TCVBG involves many different parameters not directly related to parameters of TCVBG, e.g. size of the pump beam, here we analyze the performance of TCVBG itself as a narrow-band filter in terms of Gaussian beam reflection. A wide range of resonant wavelength tunability based on a large value of the transverse chirp rate is preferred for many applications. On the other hand, in case of large chirp rate, a Gaussian beam experiences significantly different amplitude reflection coefficients over its aperture. That leads to reflectivity reduction and beam quality deterioration. We have analyzed the effect of transverse chirp rate on reflection efficiency and reflected beam quality depending on Gaussian beam size. |
Monday, March 5, 2018 1:51PM - 2:03PM |
B01.00014: Plasma damage to silicon resonators measured by internal friction Thomas Metcalf, Xiao Liu, Matthew Abernathy Plasma-based processes are widely used in microfabrication for cleaning and etching, but can result in unwanted damage to the device being fabricated. We investigate the effects of two common plasma treatments—cleaning via an oxygen plasma, and a tetrafluoromethane reactive ion etch—on silicon by measuring the internal friction of high quality factor silicon resonators before and after exposure to the plasma treatment. We find that all plasma treatments led to surface damage, as measured by an increase in internal friction, only some of which could be mitigated by post-plasma annealing at 200°C or 400°C. Additionally, there is evidence of an internal friciton peak resulting from a thin fluorinated layer after the tetrafluoromethane etch, which can be mitigated by annealing. |
Monday, March 5, 2018 2:03PM - 2:15PM |
B01.00015: Radiation Hardness of Sol-Gel Derived Zinc Oxide Thin Film Transistors Vahid Mirkhani, Shiqiang Wang, Kosala Yapabandara, Muhammad Shehzad Sultan, Min Khanal, Burcu Ozden, Sunil Uprety, Ayayi Ahyi, Dong-Joo Kim, Sarit Dhar, Michael Hamilton, Mobbassar Sk, Minseo Park Solution-derived bottom-gate zinc oxide thin film transistors (ZnO TFTs) with different number of spin-coated layers (4 layers and 8 layers) were successfully fabricated and exposed to gamma irradiation with a dosage as high as 2.2 MGy (220 MRad (air)). Zinc oxide layers were grown via sol-gel spin coating technique and were used as the active channel layer. The fabricated devices were characterized before and after being exposed to 1.2 MGy and 2.2 MGy gamma irradiation. The zinc oxide films were characterized by photoluminescence and device characteristics were extracted from the current-voltage measurements before and after irradiation. After 1.2 MGy gamma ray exposure, both 4-layer and 8-layer sample devices were functioning. Degradation in drain current ON/OFF ratio was observed for 4-layer devices while 8-layer devices exhibited an enhancement. The 8-layer ZnO TFTs remained functional after the 2.2 MGy exposure, while the 4-layer devices no longer functioned. Degradation/enhancement of device characteristics such as saturation mobility, drain current ON/OFF ratio and threshold voltage shift due to gamma ray exposure will be discussed. |
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