Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session B11: Defects in Semiconductors -- Device MaterialsFocus
|
Hide Abstracts |
Sponsoring Units: DMP DCOMP FIAP Chair: Hartwin Peelaers, University of Kansas Room: BCEC 152 |
Monday, March 4, 2019 11:15AM - 11:51AM |
B11.00001: First-principles calculations on dislocation-point defect interactions in Cu(In,Ga)Se2 solar cell absorbers Invited Speaker: Karsten Albe In Cu(In,Ga)Se2 based commercial solar cells, power-conversion efficiencies of more than 15% can be achieved, although significant dislocation densities are present. This implies that lattice dislocations in CIGSe-based absorbers are per se electrically inactive or possibly passivated by solute or impurity atoms. |
Monday, March 4, 2019 11:51AM - 12:03PM |
B11.00002: Observation of Enormous Non-Linearities in the Output Electroluminescence Characteristics of Room-Temperature GaN-Based Microcavities Aniruddha Bhattacharya Highly non-linear light (λ ~ 380 nm)-current characteristics are observed in a bulk GaN-based laterally-emitting microcavity diode at room temperature. The value of the non-linear slope, when plotted in a double logarithmic scale, increases from ~ 2 to ~ 40 at the threshold (~ 5 kA/cm2). The spectral characteristics remain essentially invariant with increasing excitation and no signatures of coherence are observed at any injection. Control measurements indirectly show that the electroluminescence originates from the p-type Mg:doped GaN contact layer. These phenomena are at least partially and qualitatively similar to previous observations of super-linear photoluminescence characteristics in Zn:doped GaN epilayers at ~ 180 K [1]. In our case, the super-linearity originates, most possibly, due to the redistribution of injected carriers between the radiative and non-radiative pathways over a particular excitation regime. Further analysis of these effects is in progress and will be presented. |
Monday, March 4, 2019 12:03PM - 12:15PM |
B11.00003: The Near-Surface Electrostatic Environment of n-Doped Silicon Probed with a Moveable Dangling Bond Point Probe Taleana Huff, Thomas Dienel, Mohammad Rashidi, Roshan Achal, wyatt vine, Robert A Wolkow With nanoelectronics reaching the limit of atom-sized devices, it has become critical to characterize how irregularities in the local environment can affect device functionality. This includes unwanted charge defects detuning binary logic atomic patterns [1], delicately coupled quantum computing states [2], and supra-layer molecular electronics [3]. In this work, we characterize charged subsurface defects on a hydrogen terminated silicon (100) sample, adding a possible explanation for a heretofore contentious negatively-charged defect. Through contact potential difference maps, taken with non-contact atomic force microscopy, variations in the electrostatic topography on a nanometer length scale are shown and correlated with alterations in the behavior of dangling bond charge state transitions. In addition, the spectroscopic signature of a single electron charge transition in a dangling bond is used as a charge sensor to directly probe the depth of charged defects, the local Debye screening length, and the effective dielectric constant close to the surface. |
Monday, March 4, 2019 12:15PM - 12:27PM |
B11.00004: Extinction of Random Telegraph Switching by “Cryogenic Annealing” in Small Area Si MOS Transistors Gangyi Hu, Mark Lee, Hisashi Shichijo, Clint A Naquin, Hal Edwards Random telegraph switching (RTS) showing a slow decay in switching rate at cryogenic temperatures that leads to eventual extinction of the discrete fluctuations has been observed in the drain-source current (IDS) of small area Si n-channel metal-oxide-semiconductor (NMOS) transistors. The RTS was characterized by IDS fluctuations between two discrete levels over a finite interval of gate bias. In all devices showing RTS, the average switching rate gradually diminished to zero over a time of 1 to 2 hours at 15 K while maintaining nearly constant fluctuation amplitude, so that the RTS eventually ceased. This decay in switching rate may be due to a metastable oxygen vacancy defect that gradually repairs itself after repeated capture and emission of charge. Once gone, RTS did not reappear in any subsequent measurements even after bias and temperature cycling, suggesting a mechanism to deactivate at least some forms of RTS through a “cryogenic anneal”. |
Monday, March 4, 2019 12:27PM - 12:39PM |
B11.00005: Hyperdoping silicon for intermediate band photoconductivity Yining Liu, Shao Qi Lim, Wenjie Yang, Phillippe K Chow, Imad Agha, James S Williams, Jeffrey M Warrender, Jay Mathews Intermediate band formation in silicon could lead the way for photodetection well below the Si band gap. By incorporating transition metals into Si at levels well above the solid solubility limit, intermediate band absorption can lead to photoconductivity induced by photons with less than the energy of the band gap. These supersaturated solutions can be fabricated using the method of ion implantation followed by pulsed laser melting. This concept has been demonstrated with Si hyperdoped with Au or Ti, but the photoresponse of detectors based on this idea have low quantum efficiency. Here we report on enhancements in the photoresponse of Si:Au and Si:Ti based detectors from varying the implantation and laser melting conditions, as well as the formation of high-quality Ohmic contacts. |
Monday, March 4, 2019 12:39PM - 12:51PM |
B11.00006: The evolution of atomic structure and chemical states of ultra-low energy high-dose Boron implanted Si via UV laser annealing Kuang Yao Lo, Fu-Ying Lee, Zong-Zhe Wu, Li-Chi Kao, Feng-Ming Chang, Yu-Ming Chang One of the most critical issues in the nano-device fabrication is to confirm the atomic structure evolution of the ultrathin shallow junction. In this report, UV Raman spectroscopy, X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS) and reflective second harmonic generation (RSHG) are used to analyze the pulse laser induced atomic structure evolution of ultralow-energy high-dose Boron implanted Si(110) at the room and cold substrate temperature. The formation of Si-B bond after the laser irradiation was indicated by a peak feature around 480 cm-1 resolved in UV Raman spectra. Meanwhile, the evolution of absorption peak (~197 eV) in XANES and the red shift of binding energy of Si element (~99 eV) in XPS reveal that the changes in the chemical states of ultra shallow junction strongly correlate to the activation process of Boron implantation. These results were confirmed by RSHG measurement, which exhibits the form symmetrical Si-B bonds. The observation of HRTEM agreed with the substrate temperature effect in the recrystallization of Boron implanted region. |
Monday, March 4, 2019 12:51PM - 1:03PM |
B11.00007: Defect studies in Ge and GeSn thin films grown on Si Christina Scott, Imad Agha, Jay Mathews Silicon (Si) is often used in electronics because of its beneficial conductive properties and cost efficiency. However, it has poor optical properties in the infrared. Si infrared photonic devices could be used for a number of military and civilian applications. One approach to solving this problem is to use epitaxy to grow materials with more favorable optical properties on top of Si, such as germanium (Ge) and germanium tin (GeSn). One challenge for epitaxy is minimizing threading dislocations in the epitaxial layers due to lattice mismatch. In this work, we investigate the quality of Ge and GeSn materials grown on Si using a new remote plasma enhanced chemical vapor deposition (CVD) process. The newly grown material was subjected to etch pit density tests in order to determine the density of threading dislocations. The results show that using this new method results in high quality achieved using traditional CVD methods while also increasing growth rates. |
Monday, March 4, 2019 1:03PM - 1:15PM |
B11.00008: Crystal growth, electronic structure and optical properties of BaZrS3 and its Ruddlesden-Popper phases Shanyuan Niu, Kristopher Williams, Wei Li, Debarghya Sarkar, Fei Hou, Boyang Zhao, Kevin Ye, Elisabeth Bianco, Michael E McConney, Ralf Haiges, David Singh, Jan Seidel, Rafael Jaramillo, Rehan Kapadia, William A Tisdale, Anderson Janotti, Jayakanth Ravichandran Transition metal perovskite chalcogenides (TMPCs) are a new class of semiconductors with d0 configuration. The less electronegative chalcogen, compared to oxides, lead to reduced band gap, more covalent bonding, and other interesting physical properties. We report the crystal growth and physical property study of BaZrS3, Ba3Zr2S7 and Ba2ZrS4. Photoluminescence (PL) measurements were performed to study the optical properties. Scanning Kelvin probe microscopy and Hall measurements were carried out to study the electronic structure and transport phenomena. Optical band gap of 1.82, 1.28 and 1.33 eV for BaZrS3, Ba3Zr2S7, and Ba2ZrS4, respectively, were extracted from PL. Such band gap evolution trend is different from that observed in oxide and halide counterparts. Potential effect of octahedra tilting and Zr-S covalent bonding in determining the electronic structure were explored. External luminescence efficiency up to 0.2% and effective minority carrier lifetime longer than 65 ns in Ba3Zr2S7 was also obtained by quantitative and time-resolved PL, respectively. |
Monday, March 4, 2019 1:15PM - 1:27PM |
B11.00009: ABSTRACT WITHDRAWN
|
Monday, March 4, 2019 1:27PM - 1:39PM |
B11.00010: Point defects and dopants of boron arsenide from first-principles calculations: donor compensation and doping asymmetry Sieun Chae, Kelsey Mengle, John Heron, Emmanouil Kioupakis BAs has received attention due to its unusually high thermal conductivity, yet, its defect properties are relatively unknown. Particularly, point defects crucially affect its electronic, thermal, and optical properties as a semiconductor. Here, we apply hybrid density functional theory calculations to identify the formation energies and thermodynamic charge transition levels of native point defects, common impurities, and shallow dopants in BAs [1]. We find that AsB, VB, BAs, Bi-VB, AsB-BAs, are the dominant intrinsic defects, while CAs, CB, Hi are common impurities. BeB, SiAs and GeAs are predicted to be excellent shallow acceptors with low ionization energy (< 0.03 eV) and negligible compensation by other point defects. However, donors such as SeAs, TeAs, SiB, and GeB have a relatively large ionization energy (~0.15 eV) and are likely to be passivated by native defects such as BAs and VB, as well as CAs, Hi, and HB. The hole and electron doping asymmetry originates from the heavy effective mass of the conduction band due to its boron orbital character, as well as from boron-related intrinsic defects that compensate donors. |
Monday, March 4, 2019 1:39PM - 1:51PM |
B11.00011: Effect of substitutional defects on the thermal conductivity of boron arsenide Nakib Protik, Mauro Fava, Natalio Mingo, Jesús Carrete, Georg Madsen, Navaneetha Krishnan Ravichandran, David A Broido Cubic boron arsenide (BAs) has recently been confirmed as having unconventional ultrahigh thermal conductivity, k, [1-3], which is particularly sensitive to the presence of vacancy defects [4]. Here, using density functional theory based first principles methods, we calculate the effect of various defects on the lattice thermal conductivity of BAs. We treat the phonon-defect scattering using both the Born approximation and the infinite-order T-matrix method and assess the difference between the results from these two approaches. The phonon-defect scattering rates are combined with the three-phonon and four-phonon scattering rates to obtain a full solution of the phonon Boltzmann transport equation. The calculated thermal conductivities are compared with the most recent experimental measurements. |
Monday, March 4, 2019 1:51PM - 2:03PM |
B11.00012: Beyond diffusion limit defect imaging and independent determination of the spatial profiles of electron and hole density near a dislocation defect by combining Raman and photoluminescence (PL) imaging Chang-Kui Hu, Qiong Chen, Fengxiang chen, Timothy Hurley Gfroerer, Mark W Wanlass, Yong Zhang Although a large carrier diffusion length (DL) indicates high material quality, ironically it implies more carrier depletion by an individual extended defect. It also obscures the spatial resolution (SR) in PL imaging, where the SR is dictated by the carrier DL rather than by the optical diffraction limit. Raman imaging of the LO phonon-plasmon (LOPP) coupled mode can be used to recover the intrinsic SR of the optical system [1], as demonstrated by Raman imaging of dislocation defects in GaAs, achieving a 10-fold improvement in SR. Furthermore, by combining Raman and PL imaging near a dislocation defect, we can independently determine the electron and hole spatial profile, radiative and nonradiative recombination rate, which has not been possible using other techniques. We find that in GaAs the dislocation defect tends to behavior as a hope trap: the defect only depletes the electrons in a short range, whereas the impact range of the defect is much larger in PL imaging. The mismatch in the electron and hole distribution implies the formation of a polarization field near the defect. The imbalance between the two charge distributions suggests the diffusion is non-ambipolar. [1] Hu et al., Light: Sci. & Appl. 7, 23 (2018). |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700