A Discussion of Electronic Optical Absorption Spectra of Nanocrystalline Silicon thin Films

1989 ◽  
Vol 164 ◽  
Author(s):  
Etienne Bustarret ◽  
M.A. Hachicha
Keyword(s):  
Room Temperature ◽  
Nanocrystalline Silicon ◽  
Low Energy ◽  
Similar Data ◽  
Silicon Thin Films ◽  
Photothermal Deflection Spectroscopy ◽  
Energy Part ◽  
Average Grain Size ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

AbstractBoth fully crystallized nanocrystalline as-deposited silicon layers with an average grain size ranging between 6 and 80 nm and mixed-phase hydrogenated doped and undoped silicon films are studied at room temperature by Photothermal Deflection Spectroscopy (PDS), Transmission Spectroscopy and Spectroscopic Ellipsometry. The differences with regard to similar data obtained on monocrystalline and hydrogenated amorphous silicon are discussed, with an emphasis on the low-energy part of the 0.6-5.6 eV explored range.

scholarly journals Photothermal Deflection Spectroscopy Study of Nanocrystalline Si (nc-Si) Thin Films Deposited on Porous Aluminum with PECVD

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
S. Ktifa ◽  
M. Ghrib ◽  
F. Saadallah ◽  
H. Ezzaouia ◽  
N. Yacoubi
Keyword(s):  
Optical Properties ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Porous Aluminum ◽  
Force Microscopy ◽  
Photothermal Deflection Spectroscopy ◽  
Atomic Force ◽  
Photothermal Deflection ◽  
Morphology Characterization

We have studied the optical properties of nanocrystalline silicon (nc-Si) film deposited by plasma enhancement chemical vapor deposition (PECVD) on porous aluminum structure using, respectively, the Photothermal Deflection Spectroscopy (PDS) and Photoluminescence (PL). The aim of this work is to investigate the influence of anodisation current on the optical properties of the porous aluminum silicon layers (PASL). The morphology characterization studied by atomic force microscopy (AFM) technique has shown that the grain size of (nc-Si) increases with the anodisation current. However, a band gap shift of the energy gap was observed.

Photoluminescence in B-doped μc-Si:H

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Q. Gu ◽  
J. M. Viner ◽  
P. C. Taylor ◽  
M. J. Williams ◽  
W. A. Turner ◽  
...  
Keyword(s):  
Broad Band ◽  
Chemical Vapor ◽  
Boron Doping ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
Band Tail ◽  
Pl Spectra ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

ABSTRACTPhotoluminescence (PL) has been investigated in hydrogenated microcrystalline silicon (μc-Si:H) samples as a function of boron doping for films prepared by remote plasma enhanced chemical vapor deposition. When the dark conductivity a is below about 10-5 S/cm, the PL spectra exhibit a shape which is close to that of the so-called band tail PL in undoped hydrogenated amorphous silicon (a-Si:H) at 77 K. When a increases, the PL intensity decreases at 77 K. For samples with a on the order of 10-3 S/cm, the PL spectra show only a narrow, low energy PL band which peaks around 0.8–0.9 eV. In these samples, the PL at higher energy is essentially not observable. This trend is similar to that which occurs in doped a-Si:H. However, for higher doping levels (σ ∼ 1 S/cm) the PL in μc-Si:H, although very weak, exhibits a broad band which contains intensity at higher energies. The absorption spectra in these samples, as measured by photothermal deflection spectroscopy (PDS), show the same relationships with the corresponding PL spectra as do the PDS spectra in doped a-Si:H.

Excitation Spectroscopy of Photoluminescence of a-Si:H

1990 ◽  
Vol 192 ◽  
Author(s):  
S. Q. Gu ◽  
P. C. Taylor
Keyword(s):  
Absorption Spectrum ◽  
Room Temperature ◽  
Tunable Laser ◽  
Excitation Source ◽  
Photoluminescence Excitation ◽  
Dangling Bond ◽  
Photothermal Deflection Spectroscopy ◽  
Photothermal Deflection ◽  
Very High

Photoluminescence excitation (PLE) spectra at 77 K have been measured over the range 1.201.75 eV using the Ti sapphire cw tunable laser as the excitation source. Two undoped a-Si:H samples on rough substrates have been investigated. The first sample has a very high dangling bond (DB) density; the second one has low DB density. The PLE spectrum of photoluminescence (PL) at 0.8 eV for the first sample follows the shape of the absorption spectrum measured by photothermal deflection spectroscopy (PDS) at room temperature. This behavior can be understood within the context of the existing models as due to recombination through defects which produces PL centered around 0.8 eV. However the PLE spectrum of PL at 0.8 eV for the second sample drops very rapidly with decreasing energy for energies less than about 1.3 eV. This behavior, which differs dramatically from that of the absorption spectrum, is consistent with earlier results and suggests that the PL measured at 0.8 eV for the second sample may be largely due to a contribution of the tail of the PL band which peaks near 1.3 eV. The PLE spectra for PL at 1.0 eV and 1.1 eV for the second sample approach the PLE spectrum previously obtained using the integrated PL intensities.

Defects in Hydrogenated Amorphous Silicon Carbide Alloys using Electron Spin Resonance and Photothermal Deflection Spectroscopy

2009 ◽  
Vol 1153 ◽  
Author(s):  
Brian J. Simonds ◽  
Feng Zhu ◽  
Josh Gallon ◽  
Jian Hu ◽  
Arun Madan ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Electron Spin Resonance ◽  
Amorphous Silicon ◽  
Electron Spin ◽  
Carbon Concentration ◽  
Hydrogenated Amorphous Silicon ◽  
Photothermal Deflection Spectroscopy ◽  
Spin Resonance ◽  
Photothermal Deflection ◽  
Hydrogenated Amorphous

AbstractHydrogenated amorphous silicon carbide alloys are being investigated as a possible top photoelectrode in photoelectrochemical cells used for hydrogen production through water splitting. In order to be used as such, it is important that the effects of carbon concentration on bonding, and thus on the electronic and optical properties, is well understood. Electron spin resonance experiments were performed under varying experimental conditions to study the defect concentrations. The dominant defects are silicon dangling bonds. At room temperature, the spin densities varied between 1016 and 1018 spins/cm3 depending on the carbon concentration. Photothermal deflection spectroscopy, which is an extremely sensitive measurement of low levels of absorption in thin films, was performed to investigate the slope of the Urbach tail. These slopes are 78 meV for films containing the lowest carbon concentration and 98 meV for those containing the highest carbon concentration.

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