scholarly journals Piezoresistor Sensor Fabrication by Direct Laser Writing on Hydrogenated Amorphous Silicon

2014 ◽  
Vol 1594 ◽  
Author(s):  
P. Alpuim ◽  
M.F. Cerqueira ◽  
G. Junior ◽  
J. Gaspar ◽  
J. Borme
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Gauge Factor ◽  
Direct Laser Writing ◽  
Laser Writing ◽  
Microscopy Imaging ◽  
Direct Laser ◽  
Hydrogenated Amorphous

ABSTRACTIn this paper we report on the 532 nm Nd:YAG laser-induced crystallization of 10 nm thick boron-doped hydrogenated amorphous silicon thin films deposited on flexible polyimide and on rigid oxidized silicon wafers by hot-wire or by plasma-enhanced chemical vapor deposition. The dark conductivity increased from ∼10-7 Ω-1cm-1, in the as-deposited films, to ∼10 and 50 Ω-1cm-1 after laser irradiation, on rigid and flexible substrates, respectively. Depending on type of substrate, laser power and fluence, a Raman crystalline fraction between 55 and 90 % was measured in HWCVD films, which was higher than observed in rf-PECVD films (35-55 %). Crystallite size remained small in all cases, in the range 6-8 nm. Due to a very high conductivity contrast (>7 orders of magnitude) between amorphous and crystallized regions, it was possible to define conductive paths in the a-Si:H matrix, by mounting the sample on a X-Y software-controlled movable stage under the laser beam, with no need for the usual lithography steps. The resistors scribed by direct laser writing had piezoresistive properties, with positive gauge factor ∼1. The details of the laser interaction process with the Si film were revealed by scanning electron microscopy imaging.

Hydrogenated Amorphous Silicon Alloys Prepared by CVD of Higher Silanes

1986 ◽  
Vol 70 ◽  
Author(s):  
Masud Akhtar ◽  
Herbert A. Weaklie
Keyword(s):  
Amorphous Silicon ◽  
Band Gap ◽  
Plasma Deposition ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Wide Band ◽  
Dark Conductivity ◽  
Attractive Alternative ◽  
Silicon Alloys ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon may be deposited at relatively low temperatures, where the density of defects may be expected to be low, by the chemical vapor deposition (CVD) of higher silanes. This method is an attractive alternative to plasma deposition techniques. We describe here the preparation of a-Si:H and related alloys incorporating carbon, germanium, and fluorine. a-Si:H films were deposited on heated substrates in the range 365°C-445°C by CVD of Si2H6 and Si3H8. The optical gap (Eg) ranged from 1.4 to 1.7 eV and the properties of films deposited from either Si2 H6 or Si3 H8 were quite similar. Wide band gap (Eg=2 eV) alloys of a-SiC:H doped with boron were prepared by CVD of disilane, methyl silane, and diborane. We also prepared variable band gap a-SiC:H alloys by substituting F2C= CFH for methylsilane, and these films were found to have approximately 1–2% fluorine incorporated. The dark conductivity of the boron doped a-SiC:H alloys dep~sited from either carbon source ranged from ix10-7 to 6x10-7 (ohm-cm)-1. We also prepared low band aap alloys of Si and Ge by CVD of trisilane and germane. The band gap of a film containing 20% Ge was 1.5 eV; however, the photoconductivity of the film was relatively low.

Effect of Ge Incorporation on Hydrogenated Amorphous Silicon Germanium Thin Films Prepared by Plasma Enhanced Chemical Vapor Deposition

2012 ◽  
Vol 569 ◽  
pp. 27-30
Author(s):  
Bao Jun Yan ◽  
Lei Zhao ◽  
Ben Ding Zhao ◽  
Jing Wei Chen ◽  
Hong Wei Diao ◽  
...  
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon germanium thin films (a-SiGe:H) were prepared via plasma enhanced chemical vapor deposition (PECVD). By adjusting the flow rate of GeH4, a-SiGe:H thin films with narrow bandgap (Eg) were fabricated with high Ge incorporation. It was found that although narrow Eg was obtained, high Ge incorporation resulted in a great reduction of the thin film photosensitivity. This degradation was attributed to the increase of polysilane-(SiH2)n, which indicated a loose and disordered microstructure, in the films by systematically investigating the optical, optoelectronic and microstructure properties of the prepared a-SiGe:H thin films via transmission, photo/dark conductivity, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) measurements. Such investigation provided a helpful guide for further preparing narrow Eg a-SiGe:H materials with good optoelectronic properties.

Preparation and Properties of Hydrogenated Amorphous Silicon Produced by Plasma-Enhanced Chemical Vapor Decomposition of Silane

1987 ◽  
Vol 95 ◽  
Author(s):  
K. L. Tokuda ◽  
D. Adler ◽  
R. Reif
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Electrical Activation ◽  
Dangling Bond ◽  
Growth Environment ◽  
Chemical Vapor Decomposition ◽  
Infrared Lamps ◽  
Hydrogenated Amorphous

AbstractWe have investigated the properties of several hydrogenated amorphous silicon (a-Si:H) films prepared by the plasma-enhanced chemical vapor decomposition (PECVD) of silane. This reactor is singular because it operates at pressures as low as 10 mTorr and uses infrared lamps to heat the growth environment. Structural characterization showed that all the samples were amorphous. Most films had hydrogen concentrations about 5%, optical gaps near 1.6 eV, and neutral dangling-bond concentrations of the order of 5 × 1016 Cm−3. Electrical activation energies were typically in the range 0.5 – 0.6 eV and the photoconductivity under ∼100 mW/cm2 white light was 10−4 (Ω-cm)−1. The dark conductivity was near 10−8(Ω-cm)−1. No significant change in dark conductivity or photoconductivity occurred after several hours of exposure to light.

High Rate Deposition of Stable Hydrogenated Amorphous Silicon in Transition from Amorphous to Microcrystalline Silicon

2003 ◽  
Vol 762 ◽  
Author(s):  
Guofu Hou ◽  
Xinhua Geng ◽  
Xiaodan Zhang ◽  
Ying Zhao ◽  
Junming Xue ◽  
...  
Keyword(s):  
Phase Transition ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
High Rate ◽  
Very High Frequency ◽  
High Quality ◽  
Working Pressure ◽  
Hydrogen Dilution ◽  
Hydrogenated Amorphous

AbstractHigh rate deposition of high quality and stable hydrogenated amorphous silicon (a-Si:H) films were performed near the threshold of amorphous to microcrystalline phase transition using a very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The effect of hydrogen dilution on optic-electronic and structural properties of these films was investigated by Fourier-transform infrared (FTIR) spectroscopy, Raman scattering and constant photocurrent method (CPM). Experiment showed that although the phase transition was much influenced by hydrogen dilution, it also strongly depended on substrate temperature, working pressure and plasma power. With optimized condition high quality and high stable a-Si:H films, which exhibit σph/σd of 4.4×106 and deposition rate of 28.8Å/s, have been obtained.

Properties of Catalytic-Cvd Amorphous Silicon-Germanium (a-SiGe:H)

1990 ◽  
Vol 192 ◽  
Author(s):  
Hideki Matsumura ◽  
Masaaki Yamaguchi ◽  
Kazuo Morigaki
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Characteristic Energy ◽  
Optical Band Gaps ◽  
Spin Resonance ◽  
Amorphous Silicon Germanium ◽  
Conductive Properties ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-germanium (a-SiGe:H) films are prepared by the catalytic chemical vapor deposition (Cat-CVD) method using a SiH4, GeH4 and H4 gas mixture. Properties of the films are investigated by the photo-thermal deflection spectroscopy (PDS) and electron spin resonance (ESR) measurements, in addition to the photo-conductive and structural studies. It is found that the characteristic energy of Urbach tail, ESR spin density and other photo-conductive properties of Cat-CVD a-SiGe:H films with optical band gaps around 1.45 eV are almost equivalent to those of the device quality glow discharge hydrogenated amorphous silicon (a-Si:H).

Effect of Nitrogen Doping on the Structure and Optical Properties of N-Type Hydrogenated Amorphous Silicon Thin Films

2011 ◽  
Vol 383-390 ◽  
pp. 6980-6985
Author(s):  
Mao Yang Wu ◽  
Wei Li ◽  
Jun Wei Fu ◽  
Yi Jiao Qiu ◽  
Ya Dong Jiang
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Hydrogenated Amorphous Silicon ◽  
Chemical Vapor ◽  
Silicon Thin Films ◽  
Frequency Plasma ◽  
Hydrogenated Amorphous

Hydrogenated amorphous silicon (a-Si:H) thin films doped with both Phosphor and Nitrogen are deposited by ratio frequency plasma enhanced chemical vapor deposition (PECVD). The effect of gas flow rate of ammonia (FrNH3) on the composition, microstructure and optical properties of the films has been investigated by X-ray photoelectron spectroscopy, Raman spectroscopy and ellipsometric spectra, respectively. The results show that with the increase of FrNH3, Si-N bonds appear while the short-range order deteriorate in the films. Besides, the optical properties of N-doped n-type a-Si:H thin films can be easily controlled in a PECVD system.

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