skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Plasticity and optical properties of GaN under highly localized nanoindentation stress fields

Authors:
 [1];  [1];  [1];  [2];  [2];  [2]; ORCiD logo [2]
  1. Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, 22453-900 Rio de Janeiro, Brazil
  2. Department of Physics, Arizona State University, Tempe, Arizona 85287-1504, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1348952
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 12; Related Information: CHORUS Timestamp: 2018-02-14 15:28:40; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Caldas, P. G., Silva, E. M., Prioli, R., Huang, J. Y., Juday, R., Fischer, A. M., and Ponce, F. A. Plasticity and optical properties of GaN under highly localized nanoindentation stress fields. United States: N. p., 2017. Web. doi:10.1063/1.4978018.
Caldas, P. G., Silva, E. M., Prioli, R., Huang, J. Y., Juday, R., Fischer, A. M., & Ponce, F. A. Plasticity and optical properties of GaN under highly localized nanoindentation stress fields. United States. doi:10.1063/1.4978018.
Caldas, P. G., Silva, E. M., Prioli, R., Huang, J. Y., Juday, R., Fischer, A. M., and Ponce, F. A. Tue . "Plasticity and optical properties of GaN under highly localized nanoindentation stress fields". United States. doi:10.1063/1.4978018.
@article{osti_1348952,
title = {Plasticity and optical properties of GaN under highly localized nanoindentation stress fields},
author = {Caldas, P. G. and Silva, E. M. and Prioli, R. and Huang, J. Y. and Juday, R. and Fischer, A. M. and Ponce, F. A.},
abstractNote = {},
doi = {10.1063/1.4978018},
journal = {Journal of Applied Physics},
number = 12,
volume = 121,
place = {United States},
year = {Tue Mar 28 00:00:00 EDT 2017},
month = {Tue Mar 28 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4978018

Citation Metrics:
Cited by: 3works
Citation information provided by
Web of Science

Save / Share:
  • Nanotwinned metals have rare combinations of mechanical strength and ductility. Previous studies have shown that detwinning occurs in plastically deformed nanotwinned metals. Although molecular dynamics simulations have predicted that fine nanotwins can migrate at low stress, there is little in situ evidence to validate such predictions. Also it is unclear if detwinning occurs prior to or succeeding plastic yielding. Here, by using in situ nanoindentation in a transmission electron microscope, we show that a non-elastic detwinning process in nanotwinned Cu occurred at ultra-low indentation stress (0.1 GPa), well before the stress necessary for plastic yielding. Furthermore, the in situ nanoindentation techniquemore » allows us to differentiate dislocation-nucleation dominated microscopic yielding preceding macroscopic yielding manifested by dislocation-transmission through twin boundaries. This study thus provides further insights for understanding plasticity in nanotwinned metals at microscopic levels.« less
  • The statistical and dynamic behaviors of the displacement-load curves of a high-entropy alloy, Al0.5 CoCrCuFeNi, were analyzed for the nanoindentation performed at two temperatures. Critical behavior of serrations at room temperature and chaotic flows at 200 °C were detected. These results are attributed to the interaction among a large number of slip bands. For the nanoindentation at room temperature, recurrent partial events between slip bands introduce a hierarchy of length scales, leading to a critical state. For the nanoindentation at 200 °C, there is no spatial interference between two slip bands, which is corresponding to the evolution of separated trajectorymore » of chaotic behavior« less
  • Samarium ions of 200 keV in energy were implanted into highly-resistive molecular-beam-epitaxy grown GaN thin films with a focused-ion-beam implanter at room temperature. The implantation doses range from 1 × 10{sup 14} to 1 × 10{sup 16 }cm{sup −2}. Structural properties studied by x-ray diffraction and Raman-scattering spectroscopy revealed Sm incorporation into GaN matrix without secondary phase. The optical measurements showed that the band gap and optical constants changed very slightly by the implantation. Photoluminescence measurements showed emission spectra similar to p-type GaN for all samples. Magnetic investigations with a superconducting quantum interference device identified magnetic ordering for Sm dose of and above 1 × 10{sup 15 }cm{sup −2}more » before thermal annealing, while ferromagnetism was only observed after thermal annealing from the sample with highest Sm dose. The long-range magnetic ordering can be attributed to interaction of Sm ions through the implantation-induced Ga vacancy.« less
  • We report the improvement of electrical and optical properties of p-GaN Ohmic metals, ZnNi(10 nm)/Au(10 nm), by ultraviolet (UV) light irradiation. After UV light irradiation, the specific contact resistance of p-GaN decreased slightly from 2.99x10{sup -4} to 2.54x10{sup -4} {omega} cm{sup 2}, while the transmittance of the contact layer increased form 75% to 85% at a wavelength of 460 nm. In addition, the forward voltage of InGaN/GaN light-emitting diode chip at 20 mA decreased from 3.55 to 3.45 V, and the output power increased form 18 to 25 mW by UV light irradiation. The low resistance and high transmittance ofmore » the p-GaN Ohmic metals are attributed to the reduced Shottky barrier by the formation of gallium oxide and the increased oxidation of p-Ohmic metals, respectively, due to ozone generated form oxygen during UV light irradiation.« less
  • A previously proposed stress corrosion cracking (SCC) mechanism incorporating localized surface plasticity (LSP), crack initiation, and crack-tip embrittlement by anodic dissolution at film rupture sites is reviewed, together with new information supporting the mechanism. Externally imposed anodic dissolution currents increase creep rates of pure metals and alloys. Creep prior to SCC has been observed frequently and may result from anodic currents at active film rupture sites caused by coupling to surrounding noble passive surfaces. Recently revealed correlations between creep rate and SCC failure times imply that mechanisms of creep and cracking may be related. Anodic attenuation of strain hardening atmore » film rupture sites may cause LSP, leading to triaxial stress conditions, suppressed slip, and crack initiation. Recent thin-film diffusion experiments show evidence of vacancy formation at anodically dissolving Cu surfaces. It has been suggested that anodically generated vacancies may increase creep and plasticity by stimulation of dislocation climb or by attraction to dislocation cores. Point-defect vacancies may weaken the crystal lattice, as do point-defect H atoms in the decohesion mechanism popular for explaining hydrogen embrittlement (HE).« less