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.

scholarly journals Morphology and luminescence of photo-electrochemically synthesized porous silicon: Influence of varying current density

2017 ◽  
Vol 13 (4) ◽  
pp. 708-710
Author(s):  
Asad Thahe ◽  
Hazri Bakhtiar ◽  
Noriah Bidin ◽  
Zainuriah Hassan ◽  
Zainal Abidin Talib ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Room Temperature ◽  
Gravimetric Method ◽  
Etching Time ◽  
Time Duration ◽  
High Quality ◽  
Force Microscopy ◽  
Room Temperature Photoluminescence ◽  
Atomic Force

Achieving high quality porous silicon (PSi) materials with desired porosity remains challenging. Three good qualities of PSi samples are prepared by Photo electro-chemically etching a piece of n-type Si inside the solution of 20 M HF, 10 M C2H5OH and 10 M H2O2 at fixed etching time duration (30 min) and varying current density (15 mA/cm2, 30 mA/cm2 and 45 mA/cm2). As-prepared sample morphologies are characterized via scanning electron microscopy (SEM) and atomic force microscopy (AFM). The gravimetric method is used to estimate the thickness and porosity of the prepared samples. Current density (etching time) dependent morphologies, electronic bandgap and room temperature photoluminescence (PL) properties of such PSi nanostructures are evaluated. These PSi structures revealed enhanced rectifying characteristics with increasing current density. 

AGING EFFECT ON THE PHOTOSYNTHESIZED POROUS SILICON

2008 ◽  
Vol 22 (04) ◽  
pp. 417-422 ◽  
Author(s):  
ALWAN M. ALWAN ◽  
OMAR A. ABDULRAZAQ
Keyword(s):  
Porous Silicon ◽  
Relative Intensity ◽  
Photoluminescence Spectrum ◽  
Room Temperature ◽  
Semiconductor Device ◽  
Aging Effect ◽  
Blue Shift ◽  
Ambient Condition ◽  
Metal Insulator ◽  
Room Temperature Photoluminescence

The photoluminescence spectrum of the freshly photosynthesized porous silicon (PS) has been investigated. This measurement was repeated after three and six months for the same sample after storage under ambient condition (open air at room temperature). Photoluminescence (PL) measurements of the stored PS show different peak positions and intensity width as compared with the results of the fresh PS. A blue shift in PL peak positions with aging time was observed. PL relative intensity is strongly diminished after 6 months of aging. Dark I-V characteristics of Al/PS/n - Si/Al structure shows a behavior of PS/n - Si isotype heterojunction for fresh device and a MIS (metal-insulator-semiconductor) device due to contribution of Al/PS Schottky barrier after aging, essentially after 6 months.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

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.

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.

Effect of current density on the porous silicon preparation as gas sensors**

2021 ◽  
Vol 30 (1) ◽  
pp. 257-264
Author(s):  
Muna H. Kareem ◽  
Adi M. Abdul Hussein ◽  
Haitham Talib Hussein
Keyword(s):  
Porous Silicon ◽  
Gas Sensors ◽  
Current Density ◽  
Room Temperature ◽  
Low Cost ◽  
High Surface ◽  
Volume Ratio ◽  
Etching Time ◽  
Force Microscopy ◽  
Materials Used

Abstract In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

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

Room Temperature Photoluminescence of Er-Doped Porous Silicon at 1.54μm

1994 ◽  
Author(s):  
Tadamasa KIMURA ◽  
Akinori YOKOI ◽  
Hisakazu HORIGUCHI ◽  
Riyu IKEDA ◽  
Riichiro SAITO ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Room Temperature Photoluminescence ◽  
Er Doped
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