Method for the Reduction of Photothermal Deflection Spectroscopy Data Taken on Amorphous Silicon (a-Si:H)

1987 ◽  
Vol 95 ◽  
Author(s):  
S. Wiedeman ◽  
M. S. Bennett ◽  
J. L. Newton
Keyword(s):  
Optical Absorption ◽  
Amorphous Silicon ◽  
Fourier Transformation ◽  
Spectroscopy Data ◽  
Interference Effects ◽  
Optical Interference ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Sensitive Method ◽  
Deposition Conditions

AbstractPhotothermal deflection spectroscopy (PDS) is a sensitive method used to measure weak optical absorption of sub-bandgap radiation. A method utilizing Fourier transformation is presented which allows removal of optical interference effects and noise which is typically present in PDS data taken on a-Si:H, yet leaves the underlying PDS spectra undistorted. The method greatly facilitates comparison of PDS spectra taken on different samples, and simplifies further analysis. Examples using a-Si samples produced under different deposition conditions are presented to demonstrate the utility of the method.

Equilibration in Amorphous Silicon Nitride Alloys

1995 ◽  
Vol 377 ◽  
Author(s):  
Bruce Dunnett ◽  
Christopher H. Cooper ◽  
Darren T. Murley ◽  
Roderick A. G. Gibson ◽  
David I. Jones ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Growth Temperature ◽  
Vapour Deposition ◽  
Defect Density ◽  
Chemical Vapour ◽  
Amorphous Silicon Nitride ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Deposition Conditions

ABSTRACTSeveral series of amorphous silicon nitride thin films have been grown by plasma-enhanced chemical vapour deposition, where the ratio of ammonia and silane feed gases was held constant for each series while the deposition temperature was varied from 160 °C to 550 °C, and all other deposition conditions were held constant. Photothermal Deflection Spectroscopy measurements were used to determine the Urbach slope E0 and the defect density ND. It is found that ND is determined by E0 for most of these samples, suggesting that defect equilibration occurs in a-SiNx:H for x up to at least 0.6. The growth temperature at which the disorder is minimised increases to higher values with increasing x, which is explained in terms of a hydrogen-mediated bond equilibration reaction. Fourier Transform Infra Red spectroscopy measurements were performed to determine the changes in hydrogen bonding with growth temperature. The results suggest that a second bond equilibration reaction also occurs at the growing surface, but that equilibrium cannot be reached at higher temperatures because of hydrogen evolution from Si-H bonds.

Photothermal Deflection Spectroscopy Investigations of Uranium Electrochemistry - II

1993 ◽  
Vol 333 ◽  
Author(s):  
James D. Rudnicki ◽  
Richard E. Russo
Keyword(s):  
Optical Absorption ◽  
Saturated Calomel Electrode ◽  
Sample Surface ◽  
Oxidation Potential ◽  
Dissolution Mechanism ◽  
Concentration Gradients ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Oxide Electrochemistry

ABSTRACTPhotothermal Deflection Spectroscopy (PDS) has been applied to the study of uranium oxide electrochemistry. PDS measures the optical absorption of the sample surface and concentration gradients formed in the electrolyte. Both of these measurements are performed in situ under dynamic conditions. The combination of these two measurements provides information that can be used to infer the mechanism of the UO2 surface chemistry. These studies of the uranium dissolution mechanism are performed in pH 10.5 sodium sulfate electrolytes at 22°C. The electrolytes are free from oxygen, and complexing species. Our results suggest that dissolution of UO2 can occur at oxidizing potentials as low as -300 mV vs. saturated calomel electrode (SCE). The optical absorption and concentration gradient results provide evidence for a substantial surface change that occurs at an oxidation potential of +300 mV. The results show that the surface layer formed by this change dissolves slowly by a non-electrochemical reaction.

scholarly journals Subgap Absorption in Conjugated Polymers

1991 ◽  
Vol 228 ◽  
Author(s):  
M. Sinclair ◽  
C. H. Seager ◽  
D. McBranch ◽  
A. J. Heeger ◽  
G. L. Baker
Keyword(s):  
Optical Absorption ◽  
Conjugated Polymers ◽  
Absorption Edge ◽  
Spectral Region ◽  
Absorption Coefficients ◽  
Photothermal Deflection Spectroscopy ◽  
Integrated Optical ◽  
Integrated Optical Devices ◽  
Photothermal Deflection ◽  
Sample Age

ABSTRACTAlong with χ(3), the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10-5, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of “transparent” materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly[1,4-phenylenevinylene] (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm-1 to 10 cm-1. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration or fluorination.

Electronic and Optical Properties of a-Si1−xCx:H Films Produced From Admixtures of Silane and Ditertiarybutylsilane

1994 ◽  
Vol 336 ◽  
Author(s):  
K. Gaughan ◽  
J.M. Viner ◽  
P.C. Taylor
Keyword(s):  
Electrical Conductivity ◽  
Silicon Carbide ◽  
Optical Properties ◽  
Chemical Vapor Deposition ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Photothermal Deflection Spectroscopy ◽  
Optical And Electronic Properties ◽  
Photothermal Deflection

ABSTRACTWe investigated the optical and electronic properties of amorphous silicon carbide (a-Si1−xCx:H) films produced by plasma enhanced chemical vapor deposition from admixtures of silane and ditertiarybutylsilane [SiH2 (C4H9) 2 or DTBS] using photothermal deflection spectroscopy, electrical conductivity and its temperature dependence as well as photoconductivity. These a-Si1−xCx:H films exhibit low Urbach energies and high photoconductivities similar to films produced with other carbon feedstock sources. We also present our results for hydrogen diluted a-Si1−xCx:H films using DTBS as the carbon feedstock source.

Optimization of Optoelectronic Properties of a-SiC:H Films

1993 ◽  
Vol 297 ◽  
Author(s):  
F. Demichelis ◽  
G. Crovini ◽  
C.F. Pirri ◽  
E. Tresso ◽  
R. Galloni ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Silicon Carbide ◽  
Ftir Spectroscopy ◽  
Amorphous Silicon ◽  
Reflectance Spectroscopy ◽  
High Hydrogen ◽  
Hydrogen Dilution ◽  
Photothermal Deflection Spectroscopy ◽  
Device Structures ◽  
Photothermal Deflection

Amorphous silicon carbide films have been deposited by PECVD in SiH4+CH4+H2 mixtures at different hydrogen dilutions. The optoelecuonic properties of the films have been measured by transmittance-reflectance spectroscopy, photothermal deflection spectroscopy and photo and dark electrical conductivity. Structural properties have been obtained by FTIR spectroscopy. It was found that high hydrogen dilution leads to materials of improved quality, p-i-n device structures have been deposited with intrinsic layers at different hydrogen dilution levels.

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