Sulfidation and Post-Sulfidatton Reactions on Gallium Arsenide

1992 ◽  
Vol 259 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Thin Film ◽  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Gaas Surface ◽  
Reflection Spectroscopy ◽  
Infrared Reflection ◽  
Considerable Controversy ◽  
Infrared Reflection Spectroscopy ◽  
Sulfur Containing

ABSTRACTChemical treatment of GaAs with sulfur-containing compounds has been shown to improve GaAs surface electronic properties. There is still considerable controversy, however, regarding the chemical nature of the surface film which results from the sulfidation, and of the basis of the electronic improvement and of the decay in the improved electronic properties with time. We have investigated the surface chemistry of the chemical sulfidation treatment of GaAs with Na2S.9H2O and (NH4)2S. Using surface infrared reflection spectroscopy (SIRS) and x-ray photoelectron spectroscopy (XPS), we have studied the GaAs surface and its behavior with time after such treatments. Results show that both of these sulfidation treatments removed the chemical oxide of GaAs, leaving behind a thin film on the surface. XPS results show that the Ga-O and As-O peaks were removed after treatment and that As-S and no Ga-S peaks were formed. Infrared results show that the film deposited after Na2S.9H2O treatment slowly reacted in air to form sodium carbonate and rhombic sulfur. In addition, this film contains compounds with sulfur-oxygen bonds, which most likely were arsenic sulfate, sulfite, and thiosulfate salts. The film deposited on the (NH4)2Streated GaAs surface was identified as ammonium thiosulfate and slowly decomposed with time. Rinsing with water removed the thin film formed after either sulfidation treatment.

Electrochemical and Chemical Sulfidation of GaAs: A Surface Chemical Study

1991 ◽  
Vol 237 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Infrared Spectroscopy ◽  
Electronic Properties ◽  
Chemical Nature ◽  
Surface Film ◽  
Chemical Study ◽  
Gaas Surface ◽  
Surface Chemical ◽  
Considerable Controversy ◽  
Oxygen Group ◽  
Sulfur Containing

ABSTRACTTreatment of gallium arsenide with sulfur-containing media has been shown to improve GaAs surface electronic properties. However, there is still considerable controversy regarding the chemical nature of the surface film which results from the sulfidation, and of the basis of the electronic improvement and of the decay in the improved electronic properties with time. We have investigated the surface chemistry of the chemical sulfidation treatment of GaAs with Na2S-9H2O and the electrochemical sulfidation treatment of GaAs with Na2S-9H2O-ethylene glycol. Using surface infrared spectroscopy (SIRS), we have studied the film formed on the surface after the treatments and its behavior with time. Results show that the film on the GaAs surface contains sulfur which is often associated with oxygen, that this film slowly reacts in air to form unexpected species, e.g. sodium carbonate and sulfur-oxygen group-containing compounds, and that sulfur and oxygen are non-uniformly distributed.

Preparation of Protective Films Containing Molybdate for Self-Healing of a Scratched Iron Surface

CORROSION ◽  
2000 ◽  
Vol 56 (9) ◽  
pp. 901-909 ◽  
Author(s):  
K. Aramaki
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sodium Molybdate ◽  
Anodic Process ◽  
Self Healing ◽  
Reflection Spectroscopy ◽  
Ammonium Heptamolybdate ◽  
X Ray ◽  
Infrared Reflection ◽  
Protective Films ◽  
Infrared Reflection Spectroscopy

Abstract Nonchromate, self-healing films protective against corrosion of Fe were assessed by polymerization of 1,2-bis(triethoxysilyl)ethane ([C2H5O]3Si[CH2]2-Si(OC2H5]3; BTESE) containing ammonium heptamolybdate ([NH4]6Mo7O244H2O), which was combined tightly with ferric ion (Fe3+) on the surface of an Fe electrode passivated in aerated 0.1 M sodium molybdate (Na2MoO4). After the electrode surface was scratched crosswise with a knife-edge, the electrode was immersed in an aerated 0.1 M sodium chloride (NaCl) solution at 30°C for > 4 h, and then polarization curves were measured in the solution potentiodynamically. The anodic process of Fe corrosion was suppressed markedly by passivation of the scratched surface with molybdate ion (MoO42−) oozing from the film and O2 diffusing through the scratch. The surface covered with the film was characterized by x-ray photoelectron spectroscopy, Fourier transform infrared reflection spectroscopy, and electron probe microanalysis.

Electrochemical Sulfur Treatments of GaAs Using Na2S and (NH4)2S Solutions: A Surface Chemical Study

1992 ◽  
Vol 282 ◽  
Author(s):  
J. Yota ◽  
V. A. Burrows
Keyword(s):  
Electronic Properties ◽  
Photoelectron Spectroscopy ◽  
Surface Film ◽  
Surface Recombination ◽  
Chemical Study ◽  
Lower Surface ◽  
State Density ◽  
Gaas Surface ◽  
Surface Recombination Velocity ◽  
Recombination Velocity

ABSTRACTChemical sulfur treatments of GaAs have been shown to improve the GaAs surface electronic properties. These treatments result in lower surface state density, lower surface recombination velocity, and shifting or unpinning of the Fermi level, in addition to improvement in the performance of devices. However, there is still considerable controversy regarding the chemical nature of the surface film which results from this chemical sulfidation. It has been shown that this film is not stable chemically and electronically. The improved surface electronic properties decay with time and are sensitive to the chemical environment of the material. In this study, using surface infrared reflection spectroscopy (SIRS) and x-ray photoelectron spectroscopy (XPS), we have investigated the electrochemical sulfidation of GaAs as a possible new method to produce a GaAs surface that is stable chemically and electronically. We have found that anodic treatments with Na2S and (NH4S solutions result in the removal of the pre-existing oxide of GaAs and the formation of films comprising sulfur, sodium carbonate, ammonium thiosulfate, and sulfide and sulfur-oxygen compounds of arsenic. Rinsing the GaAs with water removes the bulk of the film, leaving behind a surface on which only arsenic sulfide was detected.

Monitoring the effects of chemical stimuli on live cells with metasurface-enhanced infrared reflection spectroscopy

2021 ◽  
Author(s):  
Steven H. Huang ◽  
Jiaruo Li ◽  
Zhiyuan Fan ◽  
Robert Delgado ◽  
Gennady Shvets
Keyword(s):  
Intracellular Signaling ◽  
Strong Field ◽  
Detection System ◽  
Field Enhancement ◽  
Chemical Imaging ◽  
Live Cells ◽  
Label Free ◽  
Reflection Spectroscopy ◽  
Infrared Reflection ◽  
Infrared Reflection Spectroscopy

Infrared spectroscopy has found wide applications in the analysis of biological materials. A more recent development is the use of engineered nanostructures, or plasmonic metasurfaces, as substrates for metasurface-enhanced infrared reflection spectroscopy (MEIRS). Here, we demonstrate that strong field enhancement from plasmonic metasurfaces enables the use of MEIRS as a highly informative analytic technique for real-time monitoring of cells. By exposing live cells cultured on a plasmonic metasurface to chemical compounds, we show that MEIRS can be used as a label-free phenotypic assay for detecting multiple cellular responses to external stimuli: changes in cell morphology, adhesion, lipid composition of the cellular membrane, as well as intracellular signaling. Using a focal plane array detection system, we show that MEIRS also enables spectro-chemical imaging at the single-cell level. The described metasurface-based all-optical sensor opens the way to a scalable, high-throughput spectroscopic assay for live cells.

Noncontact infrared reflection spectroscopy using optical fibers

1994 ◽  
Vol 65 (8) ◽  
pp. 2731-2732 ◽  
Author(s):  
D. Bunimovich ◽  
E. Belotserkovsky ◽  
A. Katzir
Keyword(s):  
Optical Fibers ◽  
Reflection Spectroscopy ◽  
Infrared Reflection ◽  
Infrared Reflection Spectroscopy
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