Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session T45: Semiconductors: Thermodynamic & Transport Properties II |
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Sponsoring Units: FIAP Chair: John Kouvetukis, Arizona State University Room: Mile High Ballroom 4D |
Thursday, March 6, 2014 11:15AM - 11:27AM |
T45.00001: Structural and thermochemical Aspects of (III-V)IV$_{3}$ Material Assembly from First Principles Andrew Chizmeshya, John Kouvetakis Alloys with (III-V)-(IV) compositions, including Si$_{3}$(AlP), Si$_{5-2y}$(AlP)$_{y}$, Si$_{3}$Al(As$_{1-x}$N$_{x}$), Si$_{5-2y}$Al(P$_{1-x}$N$_{x}$)$_{\mathrm{y}}$ and Ge$_{5-2y}$(InP)$_{y}$ and have recently been synthesized as mono-crystalline films on Si substrates, using a synthesis route specifically designed to avoid phase separation between the III-V and IV constituents. Molecular ``building blocks'' containing group-V-centered III-V-IV$_{3}$ cores, formed via interactions of group-III atoms and reactive silyly/germyl hydride precursors of desired composition (e.g, P(SiH$_{3})_{3}$, P(GeH$_{3})_{3}$, etc), assemble to form stable, covalent, diamond-like materials with the inherent tetrahedral symmetry and composition of the III-V-IV$_{3}$ units. The resulting systems may provide access to a broad range of new semiconductor systems with extended optoelectronic properties, provided that the required molecular sources are available, the thermodynamic processes are viable, and the resulting alloy composition can be tuned to lattice-match the growth substrate. Molecular/solid-state simulations are used to identify promising synthetic pathways and guide the epitaxial creation of new (III-V)-(IV) materials. The thermodynamics of gas phase synthesis reactions, energetic stability of the alloys, and their epitaxial/chemical compatibility with the substrate are combined to form a global figure of merit. The latter corroborates the synthesis of known systems and predicts that formation of GaPSi$_{3}$/Si(100), GaAsSi$_{3}$/SiGe(100), AlPGe$_{3}$/Ge(100) and InAsSi$_{3}$/Ge(100) may also be favorable. [Preview Abstract] |
Thursday, March 6, 2014 11:27AM - 11:39AM |
T45.00002: Revealing spin-spin correlations in atomic vapors and semiconductor heterostructures using spin noise spectroscopy Dibyendu Roy, Nikolai A. Sinitsyn We discuss advantages and limitations of the spin noise spectroscopy for characterization of spin-spin correlations in various atomic vapors and semiconductor heterostructures. It is shown that all the relevant parameters of the quantum dot molecules including tunneling amplitudes with spin-conserving and spin-non-conserving interactions, decoherence rates, Coulomb repulsions, anisotropic g-factors and the distance between the dots can be determined by measuring properties of the spin noise power spectrum using a single linearly polarized detuned continuous-wave laser beam. Next we show that spin-spin interactions between two different species in an atomic vapor mixture can be revealed by measuring spin noise power spectrum with two laser beams. Finally we mention some relevant advances in spin noise spectroscopy for characterization of many-body interactions in correlated materials. [Preview Abstract] |
Thursday, March 6, 2014 11:39AM - 11:51AM |
T45.00003: Microwave spectroscopic observation of phase transition between competing solids in wide quantum wells A.T. Hatke, B.A. Magill, B.H. Moon, L.W. Engel, Y. Liu, M. Shayegan, L.N. Pfeiffer, K.W. West, K.W. Baldwin Within a narrow range of Landau filling ($\nu$) near $\nu=1$, a resonance in the microwave spectrum in high mobility two-dimensional electron systems is known to occur [1]. The resonance, characterized by a peak frequency ($f_{pk}$), is a signature of a pinned Wigner solid in which quasiparticles oscillate about their pinned positions. In wide quantum wells, at sufficiently large density, we observe an abrupt shift in $f_{pk}$ vs $\nu$ as $\nu$ is decreased from 1. We interpret this jump to enhanced-$f_{pk}$ vs $\nu$ as a solid-solid phase transition. dc transport measurements reveal a reentrant integer quantum Hall effect (RIQHE) [2], which we show has the same origin as the enhanced-$f_{pk}$. \\[4pt] [1] Chen et al., Phys. Rev. Lett. 91, 016801 (2003).\\[0pt] [2] Liu et al., Phys. Rev. Lett. 109, 036801 (2012). [Preview Abstract] |
Thursday, March 6, 2014 11:51AM - 12:03PM |
T45.00004: Bipolar surface devices on hydrogen-terminated silicon (111) surface Binhui Hu, B.E. Kane Two-dimensional systems on hydrogen-terminated Si(111) surfaces show very high quality. The peak electron mobility of 325,000 cm$^{2}$/Vs can be achieved at T$=$90 mK, and the device shows the fractional quantum hall effect [1]; the peak hole mobility of 10,000 cm$^{2}$/Vs can be reached at 70 mK, and Shubnikov-de Haas oscillations show a beating pattern due to the spin-orbit effects [2]. With the ability to create both a two-dimensional electron system (2DES) and a two-dimensional hole system (2DHS) on a Si(111) surface, it is natural to develop a bipolar surface device, similar to that on AlGaAs/GaAs heterostructures [3]. The capability to switch between electrons and holes on the same Si(111) surface is helpful for studies of interaction effects and spin related phenomena, since the electrons and holes have very different band structures, and spin properties. We have fabricated the bipolar surface devices with improved gate structures. The characteristics of the devices will be presented and the possible implication will be discussed. \\[4pt] [1] Tomasz M. Kott, Binhui Hu, S. H. Brown, and B. E. Kane, arXiv:1210.2386 (2012) \\[0pt] [2] Binhui Hu, Tomasz M. Kott, R. N. McFarland, and B. E. Kane, Appl. Phys. Lett. 100, 252107 (2012) \\[0pt] [3] J. C. H. Chen, D. Q. Wang, O. Klochan, A. P. Micolich, K. D. Gupta, F. Sfigakis, D. A. Ritchie, D. Reuter, A. D. Wieck, and A. R. Hamilton, Appl. Phys. Lett. 100, 052101 (2012) [Preview Abstract] |
Thursday, March 6, 2014 12:03PM - 12:15PM |
T45.00005: Hall Effect Measured Using a Waveguide Tee Joyce Coppock, James Anderson, William Johnson We describe a simple microwave apparatus to measure the Hall effect in semiconductor wafers. The advantage of this technique is that it does not require contacts on the sample or the use of a resonant cavity. Our method consists of placing the semiconductor wafer into a slot cut in an X-band waveguide tee, which lies in the center of an electromagnet, injecting power into the two opposing arms of the tee, and measuring the output at the third arm. Application of a magnetic field gives a Hall signal that is linear in the magnetic field and which reverses phase when the magnetic field is reversed. This method yields the semiconductor mobility, which we can compare for calibration purposes with mobility data from direct-current (Van der Pauw$^{1}$) measurements. We are in the process of modeling the system using a finite-difference time-domain (FDTD) simulation to better understand the behavior of the electric fields inside the sample. Resistivity data is obtained by measuring the microwave reflection coefficient of the sample. This talk presents data for silicon and germanium samples doped with boron or phosphorus. Measured mobilities ranged from 270-3000 $\frac{cm^2}{V \cdot s}$. $^{1}$L. J. van der Pauw, $\emph{Philips Research Reports}$ $\b{13}$, 1 (1958) [Preview Abstract] |
Thursday, March 6, 2014 12:15PM - 12:27PM |
T45.00006: Optimized efficiency and figure of merit for a tight-coupling molecular motor: their bounds and phase diagrams Mulugeta Bekele, Tadle Nuru We consider a model translational motor that consumes one fuel molecule against a given amount of load at the same physiological temperature. Taking the chemical step to be tightlly coupled to the mechanical step, we derive thermodynamic quantities such as input and output power as well as power efficiency. Using optimization criteria of energy utilization, we determine the motor's optimized efficiency as well as its figure of merit. Bounds and phase daigrams of these quantities are studied. [Preview Abstract] |
Thursday, March 6, 2014 12:27PM - 12:39PM |
T45.00007: Electronic structure and thermoelectric transport properties of Tellurium from Boltzmann transport theory Hua Peng, Nicholas Kioussis Tellurium has a trigonal structure consisting of isolated helical chains parallel to c axis. Density functional theory combined with Boltzmann transport theory was applied to investigate the electronic and thermoelectric transport properties of Tellurium in the rigid band model. Calculation results showed that $p$-type doping gives a higher \textit{ZT} and larger anisotropic behavior than $n$-type doping does. From the electronic structure, we find that the light band spitted from the spin-orbit coupling can contribute high mobility, while the drastically increased density from the heavy band bring a large asymmetry for the transport distribution function, which is benefit for the Seebeck coefficient. Besides, the band near the valence band maximum $H$ point have a saddle-shape band structure along c direction, and smaller effective mass along this direction than other two directions. The overall result is good thermoelectric property for $p$-type doping tellurium along c direction. So, our calculation results suggest that in experiment, people can get a high \textit{ZT} in tellurium by doping with small covalent electrons elements with a texture along [001] direction. [Preview Abstract] |
Thursday, March 6, 2014 12:39PM - 12:51PM |
T45.00008: Field Induced Positional Shift and Second Order Semiclassical Theory for Bloch Electrons Yang Gao, Shengyuan Yang, Qian Niu We derive a positional shift due to the interband mixing induced by external electromagnetic fields. This positional shift plays a central role in the second order semiclassical theory for Bloch electrons. It also provides rich physics, e.g. the magnetoelectric coupling, the nonlinear anomalous Hall, etc. We also derive the semiclassical wave packet energy up to second order. With these two essential corrections, we show that the second order semiclassical dynamics possesses the exact same structure as the first order one, rendering a simple generalization of various response functions. [Preview Abstract] |
Thursday, March 6, 2014 12:51PM - 1:03PM |
T45.00009: Field-Emission from Chemically Functionalized Diamond Surfaces: Does Electron Affinity Picture Work? Yoshiyuki Miyamoto, Takehide Miyazaki, Daisuke Takeuchi, Hideyo Okushi, Satoshi Yamasaki By means of the time-dependent density functional electron dynamics, we have revisited the field-emission efficiency of chemically functionalized diamond (100) surfaces. In order to achieve high efficiency and high (chemical) stability, proper chemical species are needed to terminate diamond surfaces. Hydrogen (H) termination is well known to achieve the negative electron affinity (NEA) of diamond surface which indeed enhances field emission performance than that of clean surface with positive electron affinity (PEA). Yet, the durability of H-terminated diamond surface was concerned for long-time operation of the field-emission. Meantime, oxidation, or hydroxyl (OH) termination was considered to achieve chemical stability of the surface but presence of oxygen (O) atom should reduce the emission efficiency. Recently, H- OH-co-terminated surface is reported as NEA and was expected to achieve both emission efficiency and chemical stability. However, our simulation showed that emission efficiency of the H- OH- co-terminated surface is much lower than clean surface with PEA, thus we note that the electron affinity cannot be a unique measure to determine the emission efficiency. In this talk, we introduce necessity of new concept to understand the emission efficiency which needs to know detailed potential profile from bulk to vacuum through surface, which is strongly dependent on the surface chemical functionalization. This work was supported by ALCA project conducted by Japan Science and Technology Agency. [Preview Abstract] |
Thursday, March 6, 2014 1:03PM - 1:15PM |
T45.00010: The influence of Atomic Oxygen on the Figure of Merit of Indium Tin Oxide thin Films grown by reactive Dual Ion Beam Sputtering Wilhelmus Geerts, Nelson Simpson, Allen Woodall, Maclyn Compton Indium Tin Oxide (ITO) is a transparent conducting oxide that is used in flat panel displays and optoelectronics. Highly conductive and transparent ITO films are normally produced by heating the substrate to 300 Celsius during deposition excluding plastics to be used as a substrate material. We investigated whether high quality ITO films can be sputtered at room temperature using atomic instead of molecular oxygen. The films were deposited by dual ion beam sputtering (DIBS). During deposition the substrate was exposed to a molecular or an atomic oxygen flux. Microscope glass slides and silicon wafers were used as substrates. A 29 nm thick SIO2 buffer layer was used. Optical properties were measured with a M2000 Woollam variable angle spectroscopic ellipsometer. Electrical properties were measured by linear four point probe using a Jandel 4pp setup employing silicon carbide electrodes, high input resistance, and Keithley low bias current buffer amplifiers. The figure of merit (FOM), i.e. the ratio of the conductivity and the average optical absorption coefficient (400-800 nm), was calculated from the optical and electric properties and appeared to be 1.2 to 5 times higher for the samples sputtered with atomic oxygen. The largest value obtained for the FOM was 0.08 reciprocal Ohms. [Preview Abstract] |
Thursday, March 6, 2014 1:15PM - 1:27PM |
T45.00011: Modeling of band alignment at the $\beta $-Ga$_{2}$O$_{3}$/$\beta $-(Ga$_{\mathrm{1-x}}$M$_{\mathrm{x}})_{2}$O$_{3}$ interface (M$=$Al, In) Stefan Badescu, Gregg Jessen Beta gallium oxide ($\beta $-Ga$_{2}$O$_{3})$ is receiving a significant attention as a possible native substrate for electronic devices. The band alignment and electron accumulation at the interface between $\beta $-Ga$_{2}$O$_{3}$ and its alloys remains an open question. We describe our modeling of $\beta $-Ga$_{2}$O$_{3}$/$\beta $-(Ga$_{\mathrm{1-x}}$M$_{\mathrm{x}})_{2}$O$_{3}$ (M$=$Al, In) interfaces based on the density functional theory. These are using the LDA$+$U method with large simulation cells with Hubbard U parameters extracted from accurate GW models. We find a range of compositions with relevant band shifts and a range of alloy epilayer thickness as a function of lattice mismatch. [Preview Abstract] |
Thursday, March 6, 2014 1:27PM - 1:39PM |
T45.00012: Electronic transport properties of epitaxial SnO$_{2}$ (101) on r-plane sapphire substrate by pulsed laser deposition Hyosik Mun, Jisung Park, Chanjong Ju, Hoon Min Kim, Useong Kim, Kookrin Char The electrical transport characteristics of epitaxial tin oxide have been investigated in various ranges of the growth oxygen pressure and the film thickness. Pulsed laser deposition has been used to grow epitaxial thin films of SnO$_{2}$ or r-plane sapphire substrate. The SnO$_{2}$ films are epitaxial with the rutile structure, resulting from the high similarity in oxygen octahedral configurations between the r-plane sapphire surface and the SnO$_{2}$ (101) surface. Hall measurements show that the low electron mobility at small thickness region increases gradually when the films become thicker. On the other hand, the carrier concentration increases as the film thickness increases, contrary to the previously reported effect of the line dislocations as donors. The thickness dependence show that the mobility of 2.95 cm$^{2}$/V s for 30 nm thickness increases to 97.3 cm$^{2}$/V s for 1000 nm thickness and the electron concentration increases from 9.0 $\times$ 10$^{17}$ to 2.4 $\times$ 10$^{18}$ cm$^{-3}$ at the same time. We found the linear and planar defects interrupt electron transport properties of epitaxial tin oxide. We will report on the correlation between the electronic transport properties and the various structural defects in epitaxial tin oxide on r-plane sapphire. [Preview Abstract] |
Thursday, March 6, 2014 1:39PM - 1:51PM |
T45.00013: ABSTRACT WITHDRAWN |
Thursday, March 6, 2014 1:51PM - 2:03PM |
T45.00014: Disorder in ZnSnN$_{2}$: Characterization and Band Structure Effects N. Feldberg, W.M. Linhart, T.D. Veal, P.A. Stampe, R.J. Kennedy, D.O. Scanlon, L.F.J. Piper, Y. Yang, R. Clarke, R.J. Reeves, S.M. Durbin ZnSnN$_{2}$ represents a critical member of the Zn-IV-N$_{2}$ family of materials proposed as alternatives to conventional III-V semiconductors for use in optoelectronic devices. Importantly, it consists of what are known as ``earth abundant'' elements. This compound is predicted to exhibit a tetragonal ordering and to crystallize in an orthorhombic lattice structure. In contrast with density functional theory calculations, films grown by molecular beam epitaxy appear to have a monoclinic structure with $\gamma $\textgreater 118$^{\circ}$, possibly due to the disordering of the Zn-Sn sublattice. Similar effects having been seen in other members of the family. We show that increasing cation sublattice disorder is predicted to cause a decrease in the band gap, theoretically by a full 0.9 eV and may be useful for device engineering. Hall Effect shows a degenerate carrier concentration in all samples to date, likely due to disorder and/or deviations from stoichiometry. The onset of optical absorption occurs at higher energy in samples with lower carrier concentrations and ranges from 2-2.4 eV. We see evidence for this in hard x-ray photoelectron spectroscopy, along with signs of band filling. Increasing cation sublattice disorder may be competing with Moss-Burstein band filling. [Preview Abstract] |
Thursday, March 6, 2014 2:03PM - 2:15PM |
T45.00015: First-principles studies of dilute magnetic ferroelectrics Leigh Weston, Xiangyuan Cui, Simon P. Ringer, Catherine Stampfl Using first-principles density functional calculations, we have investigated the magnetic properties of dilute magnetic ferroelectrics (DMF), where a nominally non-magnetic ferroelectric host is doped with a small concentration of magnetic impurities. We find that DMFs may exhibit simultaneous electrical and magnetic polarization, consistent with recent experimental observations. A possible mechanism for magnetoelectric coupling was explored, and it was found that through a strong spin-lattice coupling, electric field induced switching of magnetization may be possible. Thus, DMFs may provide a route to achieving a single phase, room temperature multiferroic with strong magnetoelectric coupling. [Preview Abstract] |
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