Photoelectron spectroscopy measurements of the band gap in porous silicon

1993 ◽  
Vol 63 (21) ◽  
pp. 2911-2913 ◽  
Author(s):  
T. van Buuren ◽  
T. Tiedje ◽  
J. R. Dahn ◽  
B. M. Way
Keyword(s):  
Porous Silicon ◽  
Band Gap ◽  
Photoelectron Spectroscopy

Comparison of the Band Gap of Porous Silicon as Measured by Photoelectron Spectroscopy and Photoluminescence

1994 ◽  
Vol 358 ◽  
Author(s):  
T. Van Buuren ◽  
S. Eisebitt ◽  
S. Patitsas ◽  
S. Ritchie ◽  
T. Tiedje ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Band Gap ◽  
Current Density ◽  
Absorption Edge ◽  
Photoelectron Spectroscopy ◽  
Photoluminescence Spectrum ◽  
Room Temperature ◽  
Room Temperature Photoluminescence ◽  
Preparation Conditions ◽  
Peak Energy

ABSTRACTThe peak energy of the room temperature photoluminescence of porous silicon is compared with the bandgap determined from photoelectron spectroscopy measurements for a series of porous silicon samples prepared under different conditions. The photoluminescence bandgap is found to be smaller than the photoelectron spectroscopy bandgap, but exhibits the same trend with preparation conditions. The width of both the photoluminescence spectrum and the L-absorption edge increases when the current density during the preparation is increased or the sample is allowed to soak in HF after preparation.

CdTe Thin Film Solar Cells: The CdS/SnO2 Front Contact

2001 ◽  
Vol 668 ◽  
Author(s):  
J. Fritsche ◽  
S. Gunst ◽  
A. Thiβen ◽  
R. Gegenwart ◽  
A. Klein ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Tin Dioxide ◽  
Surface Preparation ◽  
Thin Film Solar Cells ◽  
Subsequent Formation ◽  
Coated Glass ◽  
Preparation Conditions

ABSTRACTTin dioxide (SnO2) coated glass is the commonly used substrate for thin film solar cells based on CdTe absorbers. We have investigated the properties of the CdS/SnO2 interface by X-ray and ultraviolet photoelectron spectroscopy. SnO2 coated glass substrates as used for solar cell preparation were cleaned by different procedures such as derinsing, sputtering, heating and annealing in oxygen atmosphere. Different surface properties with a strongly dependent number of defects in the SnO2 band gap are identified. CdS films were deposited stepwise by thermal evaporation to determine the electronic interface properties for different surface preparation conditions. Comparative barrier heights at the CdSSnO2 contact are found for most surface pretreatments. The Fermi level position in these cases is situated in the SnO2 band gap. A different interface behaviour is determined for sputter cleaned SnO2 surfaces, which is attributed to the formation of oxygen vacancies during sputtering and subsequent formation of an interfacial SnOxSy compound.

Preparation and characterization of V2O5 doped SiO2-TiO2 thin films

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Marek Nocuń ◽  
Sławomir Kwaśny
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Dip Coating ◽  
Band Gap Energy ◽  
Tio2 Thin Films ◽  
Glass Substrates ◽  
Gel Technique

AbstractIn our investigation, V doped SiO2/TiO2 thin films were prepared on glass substrates by dip coating sol-gel technique. Chemical composition of the samples was studied by X-ray photoelectron spectroscopy (XPS). Transmittance of the samples was characterized using UV-VIS spectrophotometry. Subsequently band-gap energy (Eg) was estimated for these films. Powders obtained from sols were characterized by FTIR spectroscopy. It was found that vanadium decreases optical band gap of SSiO2/TiO2 films.

Gold nanoclusters reductively deposited on porous silicon: morphology and electronic structures

1998 ◽  
Vol 76 (11) ◽  
pp. 1707-1716 ◽  
Author(s):  
I Coulthard ◽  
S Degen ◽  
Y -J Zhu ◽  
T K Sham
Keyword(s):  
Gold Nanoparticles ◽  
Porous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gold Nanoclusters ◽  
Gold Complex ◽  
X Ray Diffraction ◽  
Complex Ions ◽  
X Ray ◽  
Preparation Conditions ◽  
P Type

Utilizing porous silicon as a reducing agent and a substrate, gold complex ions [AuCl4]- were reduced from aqueous solution to produce nanoparticles of gold upon the surface of porous silicon. Scanning electron microscopy (SEM) was utilized to study the morphology of the porous silicon layers and the deposits of gold nanoparticles. It is found that preparation conditions have a profound effect on the morphology of the deposits, especially on porous silicon prepared from a p-type wafer. The gold nanoparticles, varying from micrometric aggregates of clusters of the order of 10 nm, to a distribution of nearly spherical clusters of the order of 10 nm, to strings of ~10 nm were observed and compared to bulk gold metal using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). These techniques confirm and complement the SEM findings. The potential for this reductive deposition technique is noted.Key words: gold nanostructures, reductive deposition, porous silicon, morphology, X-ray spectroscopy.

scholarly journals Photonic band-gap guidance in high-porosity luminescent porous silicon

2001 ◽  
Vol 79 (19) ◽  
pp. 3017-3019 ◽  
Author(s):  
P. Ferrand ◽  
D. Loi ◽  
R. Romestain
Keyword(s):  
Porous Silicon ◽  
Band Gap ◽  
Photonic Band Gap ◽  
High Porosity ◽  
Photonic Band

Visible Electro- and Photoluminescence from Porous Silicon and its Related Optoelectronic Properties

1991 ◽  
Vol 256 ◽  
Author(s):  
Nobuyoshi Koshida ◽  
Hideki Koyama
Keyword(s):  
Porous Silicon ◽  
Optical Absorption ◽  
Size Effect ◽  
Band Gap ◽  
Visible Region ◽  
Optoelectronic Properties ◽  
Porous Si ◽  
Quantum Size ◽  
Effect Model ◽  
Injection Type

ABSTRACTThe optoelectronic properties of porous Si (PS) are presented in terms of electroluminescence (EL), photoluminescence (PL), photoconduction (PC), and optical absorption. Observations of injection-type EL, efficient PL, band-gap widening, and photosensitivities In the visible region are consistent with the quantum size effect model in PS.

scholarly journals Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5043
Author(s):  
Chia-Hsun Hsu ◽  
Xin-Peng Geng ◽  
Wan-Yu Wu ◽  
Ming-Jie Zhao ◽  
Xiao-Ying Zhang ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Band Gap ◽  
Photoelectron Spectroscopy ◽  
High Speed ◽  
Oxygen Vacancies ◽  
Annealing Temperature ◽  
Atomic Layer ◽  
Zno Films ◽  
X Ray ◽  
Layer Deposition

In this study, aluminum-doped zinc oxide (Al:ZnO) thin films were grown by high-speed atmospheric atomic layer deposition (AALD), and the effects of air annealing on film properties are investigated. The experimental results show that the thermal annealing can significantly reduce the amount of oxygen vacancies defects as evidenced by X-ray photoelectron spectroscopy spectra due to the in-diffusion of oxygen from air to the films. As shown by X-ray diffraction, the annealing repairs the crystalline structure and releases the stress. The absorption coefficient of the films increases with the annealing temperature due to the increased density. The annealing temperature reaching 600 °C leads to relatively significant changes in grain size and band gap. From the results of band gap and Hall-effect measurements, the annealing temperature lower than 600 °C reduces the oxygen vacancies defects acting as shallow donors, while it is suspected that the annealing temperature higher than 600 °C can further remove the oxygen defects introduced mid-gap states.

scholarly journals Porous Silicon-Zinc Oxide Nanocomposites Prepared by Atomic Layer Deposition for Biophotonic Applications

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1987 ◽  
Author(s):  
Mykola Pavlenko ◽  
Valerii Myndrul ◽  
Gloria Gottardi ◽  
Emerson Coy ◽  
Mariusz Jancelewicz ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Optical Properties ◽  
Porous Silicon ◽  
Atomic Layer Deposition ◽  
Photoelectron Spectroscopy ◽  
Atomic Layer ◽  
Visible Range ◽  
Optical Biosensing ◽  
X Ray ◽  
Layer Deposition

In the current research, a porous silicon/zinc oxide (PSi/ZnO) nanocomposite produced by a combination of metal-assisted chemical etching (MACE) and atomic layer deposition (ALD) methods is presented. The applicability of the composite for biophotonics (optical biosensing) was investigated. To characterize the structural and optical properties of the produced PSi/ZnO nanocomposites, several studies were performed: scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance, and photoluminescence (PL). It was found that the ALD ZnO layer fully covers the PSi, and it possesses a polycrystalline wurtzite structure. The effect of the number of ALD cycles and the type of Si doping on the optical properties of nanocomposites was determined. PL measurements showed a “shoulder-shape” emission in the visible range. The mechanisms of the observed PL were discussed. It was demonstrated that the improved PL performance of the PSi/ZnO nanocomposites could be used for implementation in optical biosensor applications. Furthermore, the produced PSi/ZnO nanocomposite was tested for optical/PL biosensing towards mycotoxins (Aflatoxin B1) detection, confirming the applicability of the nanocomposites.

Near ambient pressure X-ray photoelectron spectroscopy monitoring of the surface immobilization cascade on a porous silicon-gold nanoparticle FET biosensor

2019 ◽  
Vol 492 ◽  
pp. 362-368 ◽  
Author(s):  
Chloé Rodriguez ◽  
Paul Dietrich ◽  
Vicente Torres-Costa ◽  
Virginia Cebrián ◽  
Cristina Gómez-Abad ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Gold Nanoparticle ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Surface Immobilization ◽  
X Ray
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