Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

Zinc Oxide Nano Walls Synthesized by Chemical Vapor Deposition

2014 ◽  
Vol 608 ◽  
pp. 127-131 ◽  
Author(s):  
Suttinart Noothongkaew ◽  
Supakorn Pukird ◽  
Worasak Sukkabot ◽  
Ki Seok An
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Green Emission ◽  
X Ray Diffraction ◽  
Ultraviolet Emission ◽  
Axis Orientation ◽  
X Ray ◽  
Zno Nanostructure

ZnO nanowalls were synthesized by chemical vapor deposition at temperature of 650 °C for 1 hour on the silicon substrate. The morphologies of samples were characterized by scanning electron microscopy (SEM). The result from X-ray diffraction (XRD) confirmed that the ZnO nanowalls were vertical c-axis orientation. A room temperature Photoluminescence peak at 378 nm is ultraviolet emission (UV) and the broad peak at wavelengths around 450-650 nm is corresponding to the green emission of ZnO nanostructure. This synthesis may be applicable for gas sensor or solar cells.

Structural Nature of Nanocrystalline Silicon

1993 ◽  
Vol 297 ◽  
Author(s):  
Weiqiang Han ◽  
Gaorong Han ◽  
Jianmin Qiao ◽  
Piyi Du ◽  
Zhishang Ding ◽  
...  
Keyword(s):  
High Resolution ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resolution Electron ◽  
Average Grain Size ◽  
Structural Nature

Nanocrystalline silicon (nc-Si:H) films with an average grain size ranging between 2 and 10 nm are prepared in a modified plasma chemical vapor deposition system. X-ray diffraction, transmission electron diffraction, and high resolution electron microscope are used to elucidate the structural nature in the deposited nc-Si:H films. The lattice network of the deposited silicon films changes from disordered structure to ordered structure with the increasing of plasma energy. The results also show that the crystal lattice of the nc-Si:H film is distorted from those of microcrystalline silicon and crystalline silicon. In the observed x-ray diffraction, there are two anomalous peaks at 2θ = 29.5° and 32.5° of Si besides the normal peaks at 2θ = 28.5° of Si(111) and 2θ = 47.3°of Si(220). By the high resolution electron microscopy study, a new crystallography structure with distorted Si(111) crystallites in nc- Si:H films is found. Based on our results, a structure model of nc-Si:H films is proposed.

Room temperature copolymerization to improve the thermal and dielectric properties of polyxylylene thin films by chemical vapor deposition

1994 ◽  
Vol 9 (12) ◽  
pp. 3125-3130 ◽  
Author(s):  
Justin F. Gaynor ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Weight Loss ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conformal Coatings

Polyxylylene thin films grown by chemical vapor deposition (CVD) have long been utilized for uniform, pinhole-free conformal coatings. Homopolymer films are highly crystalline and have a glass transition temperature around room temperature. We show room temperature copolymerization with previously untested comonomers during the CVD process. Samples were studied with wavelength dispersive analysis, FTIR, scanning variable angle ellipsometry, and x-ray diffraction. Copolymerizing chloro-p-xylylene with perfluoro-octyl methacrylate results in dielectric constants at optical frequencies as low as 2.19, compared to 2.68 for the homopolymer. Copolymerizing p-xylylene with 4-vinylbiphenyl resulted in films whose onset of weight loss in TGA measurements was 450 °C, compared to 270 °C for the homopolymer.

Microcharacterization of liquid delivery metalorganic chemical vapor deposition processed thin film materials exhibiting giant magnetoresistance

1999 ◽  
Vol 14 (5) ◽  
pp. 2007-2011 ◽  
Author(s):  
M. L. Weaver ◽  
L. P. M. Brandao ◽  
H. Garmestani ◽  
E. S. Gillman ◽  
K. H. Dahmen ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metalorganic Chemical ◽  
Liquid Delivery

Thin films of La0.6Ca0.4MnO3 (LCMO) have been produced on (001) oriented LaAlO3 (LAO) and yttrium-stabilized zirconia (YSZ) substrates by liquid-delivery metalorganic chemical vapor deposition (LD-MOCVD). X-ray diffraction (XRD) analyses showed that the films were epitaxially grown on LAO substrates and were monocrystalline at a thickness of less than 500 Å. At a thickness of greater than 500 Å, the films became polycrystalline but maintained their high texture (preferred crystalline orientation). Films grown on YSZ were always polycrystalline but were also highly oriented. Regardless of the substrate, the 1500 Å thick polycrystalline films exhibited substantially significant magnetoresistance ratios even above room temperature.

OMCVD of thin films from metal diketonates and triphenylbismuth

1990 ◽  
Vol 5 (6) ◽  
pp. 1169-1175 ◽  
Author(s):  
A. D. Berry ◽  
R. T. Holm ◽  
M. Fatemi ◽  
D. K. Gaskill
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Strontium Barium ◽  
X Ray ◽  
Scanning Electron

Films containing the metals copper, yttrium, calcium, strontium, barium, and bismuth were grown by organometallic chemical vapor deposition (OMCVD). Depositions were carried out at atmospheric pressure in an oxygen-rich environment using metal beta-diketonates and triphenylbismuth. The films were characterized by Auger electron spectroscopy, Nomarski and scanning electron microscopy, and x-ray diffraction. The results show that films containing yttrium consisted of Y2O3 with a small amount of carbidic carbon, those with copper and bismuth were mixtures of oxides with no detectable carbon, and those with calcium, strontium, and barium contained carbonates. Use of a partially fluorinated barium beta-diketonate gave films of BaF2 with small amounts of BaCO3.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

Real-Time Composition And Thickness Control Techniques In A Metalorganic Chemical Vapor Deposition Process

1995 ◽  
Vol 406 ◽  
Author(s):  
M. S. Gaffneyt ◽  
C. M. Reavesl ◽  
A. L Holmes ◽  
R. S. Smith ◽  
S. P. DenBaars
Keyword(s):  
Chemical Vapor Deposition ◽  
Real Time ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Normal Operation ◽  
Growth Monitoring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metalorganic Chemical

AbstractMetalorganic chemical vapor deposition (MOCVD) is a process used to manufacture electronic and optoelectronic devices that has traditionally lacked real-time growth monitoring and control. We have developed control strategies that incorporate monitors as real-time control sensors to improve MOCVD growth. An analog control system with an ultrasonic concentration monitor was used to reject bubbler concentration disturbances which exist under normal operation, during the growth of a four-period GaInAs/InP superlattice. Using X-ray diffraction, it was determined that the normally occurring concentration variations led to a wider GaInAs peak in the uncompensated growths as compared to the compensated growths, indicating that closed loop control improved GaInAs composition regulation. In further analysis of the X-ray diffraction curves, superlattice peaks were used as a measure of high crystalline quality. The compensated curve clearly displayed eight orders of satellite peaks, whereas the uncompensated curve shows little evidence of satellite peaks.

Chemical Vapor Deposition of Strontium-Barium-Niobate

1991 ◽  
Vol 243 ◽  
Author(s):  
A. Greenwald ◽  
M. Horenstein ◽  
M. Ruane ◽  
W. Clouser ◽  
J. Foresi
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Strontium Barium Niobate ◽  
Electrical And Optical Properties ◽  
Strontium Barium ◽  
X Ray ◽  
Boston University

AbstractSpire Corporation has deposited strontium-barium-niobate by chemical vapor deposition at atmospheric pressure using Ba(TMHD), Sr(TMHD), and Nb ethoxide. Deposition temperature as 550°C in an isothermal furnace. Films were deposited upon silicon (precoated with silica), platinum, sapphire, and quartz. Materials were characterized by RBS, X-ray diffraction, EDS, electron, and optical microscopy. Electrical and optical properties were measured at Boston University.

Stress in Hydrogenated Microcrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
D. Peiró ◽  
C. Voz ◽  
J. Bertomeu ◽  
J. Andreu ◽  
E. Martínez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
X Ray Diffraction ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Silicon Thin Films ◽  
Abrupt Changes

AbstractHydrogenated microcrystalline silicon films have been obtained by hot-wire chemical vapor deposition (HWCVD) in a silane and hydrogen mixture at low pressure (<5 × 10-2 mbar). The structure of the samples and the residual stress were characterised by X- ray diffraction (XRD). Raman spectroscopy was used to estimate the volume fraction of the crystalline phase, which is in the range of 86 % to 98%. The stress values range between 150 and -140 MPa. The mechanical properties were studied by nanoindentation. Unlike monocrystalline wafers, there is no evidence of abrupt changes in the force-penetration plot, which have been attributed to a pressure-induced phase transition. The hardness was 12.5 GPa for the best samples, which is close to that obtained for silicon wafers.

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