Growth of Amorphous and Crystalline Silicon by HR-CVD (Hydrogen Radical Enhanced CVD)

1987 ◽  
Vol 95 ◽  
Author(s):  
N. Shibata ◽  
K. Fukuda ◽  
H. Ohtoshi ◽  
J. Hanna ◽  
S. Oda ◽  
...  
Keyword(s):  
Thin Films ◽  
Gas Phase ◽  
Marked Improvement ◽  
Crystalline Silicon ◽  
Three Dimensional ◽  
Active Species ◽  
Hole Transport ◽  
Gas Phase Reactions ◽  
Hydrogen Radical ◽  
Si Films

AbstractSystematic studies have been made on preparation of Si thin films from SiF4 under control over the flow of atomic hydrogens. The gas phase reactions taking place in the mixture of fragments (SiFn) resulting from plasma-induced dissociation and atomic hydrogens were widely investigated by a mass spectroscopy. Chemically active species,i.e., SiF2H and SiH2F were found as those related to the growth of films. The growth in the vicinity of substrates involves either endothermic or radical-enhanced reaction for the propagation of the three dimensional Si networks, accompaning release of terminators such as H and F. Accordingly, Si thin films with structures from amorphous to crystalline were obtained by controlling the flow of atomic hydrogen. A marked improvement in the hole-transport was established in the Si films containing hydrogen less than 5–6 at % due to the reduction in the tail states near the valence band.

Si + SiH4 Reactions and Implications for Hot-Wire CVD of a-Si:H: Computational Studies

2000 ◽  
Vol 609 ◽  
Author(s):  
Richard P. Muller ◽  
Jason K. Holt ◽  
David G. Goodwin ◽  
William A. Goddard
Keyword(s):  
Quantum Chemistry ◽  
Amorphous Silicon ◽  
Gas Phase ◽  
Computational Studies ◽  
Hot Wire ◽  
Gas Phase Reactions ◽  
High Quality ◽  
Gas Phase Chemistry ◽  
Si Films ◽  
Phase Chemistry

ABSTRACTGas phase chemistry is believed to play an important role in hot-wire CVD of amorphous silicon, serving to convert the highly-reactive atomic Si produced at the wire into a less-reactive species by reaction with ambient SiH4. In this paper, we use quantum chemistry computations (B3LYP/cc-pvTZ) to examine the energetics and rates of possible gas-phase reactions between Si and SiH4. The results indicate that formation of disilyne (Si2H2) is energetically favorable. Unlike other products of this reaction, Si2H2 does not require collisional stabilization, and thus this species is the most likely candidate for a benevolent precursor that participates in the growth of high-quality Si films.

Preparation of Si Thin Films by Spontaneous Chemical Deposition

1989 ◽  
Vol 149 ◽  
Author(s):  
Jun-Ichi Hanna ◽  
Akira Kamo ◽  
Tohru Komiya ◽  
Hien D. Nguyen ◽  
Isamu Shimizu ◽  
...  
Keyword(s):  
Thin Films ◽  
Gas Phase ◽  
Gas Flow ◽  
Chemical Deposition ◽  
Phase Reaction ◽  
Gas Phase Reactions ◽  
Reduced Pressure ◽  
Gas Phase Reaction ◽  
Gas Flow Ratio ◽  
Novel Method

ABSTRACTA novel method for preparing photoconductive Si thin films termed “Spontaneous Chemical Deposition”, is proposed, in which silane is decomposed spontaneously by gas phase reactions with fluorine at reduced pressure. With the external parameters in the gas phase reaction such as a gas flow ratio of SiH4 to F2 and the reaction pressure and temperature, the Si-network structure of the films can be controlled intentionally, resulting in a reduction of the hydrogen content, CH and a variety of the films from “amorphous” to “microcrystalline”.

Constitution of Three-Dimensional Polymers and the Theory of Gelation

1942 ◽  
Vol 15 (4) ◽  
pp. 812-819 ◽  
Author(s):  
Paul J. Flory
Keyword(s):  
Gas Phase ◽  
Saturated Vapor ◽  
Three Dimensional ◽  
Critical Value ◽  
Polymer Chains ◽  
Gel Point ◽  
Gas Phase Reactions ◽  
Extreme Caution ◽  
Molecular Weights ◽  
Protein Gels

Abstract In three-dimensional polymerizations, gelation is due to the formation of network structures of indefinite extent. These giant structures make their appearance when the degree of branching or cross-linking of the polymer chains exceeds a critical value. Gelation may be considered analogous to explosion in gas-phase reactions propagated by chains which undergo branching. After gelation has occurred, the sharp distinction between gel and sol is analogous to the demarcation between a liquid and its saturated vapor. Observed average molecular weights of three-dimensional polymers must be interpreted with extreme caution, owing to the peculiarity of the distribution of species in the vicinity of the gel point. Applications of the theory to raw rubber, protein gels, and inorganic gels have been discussed.

Deposition of Si Thin Films by Reactive CVD

1995 ◽  
Vol 377 ◽  
Author(s):  
Jun-Ichi Hanna
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Gas Phase ◽  
Film Growth ◽  
Chemical Deposition ◽  
Gas Phase Reactions ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Thermal Cvd

ABSTRACTA new concept of Reactive CVD is proposed for the low-temperature growth of thin films by CVD and discussed in terms of general features of such film growth. One demonstrated example of the reactive CVD, called Spontaneous Chemical Deposition, features gas phase reactions of silane with fluorine is outlined in terms of the general characteristics of the film growth and properties.In addition, a second example of reactive CVD, called Reactive Thermal CVD and involving thermal CVD of poly-SiGe from germanium fluoride and disilane, is discussed and low-temperature growth using this method is reviewed.

Formation of Large, Orientation-Controlled, Nearly Single Crystalline Si Thin Films on SiO2 Using Contact Printing of Rolled and Annealed Nickel Tapes

2003 ◽  
Vol 762 ◽  
Author(s):  
Hwang Huh ◽  
Jung H. Shin
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Amorphous Silicon ◽  
Tem Analysis ◽  
Contact Printing ◽  
Single Crystalline ◽  
High Resolution Tem ◽  
Lateral Crystallization ◽  
Si Films

AbstractAmorphous silicon (a-Si) films prepared on oxidized silicon wafer were crystallized to a highly textured form using contact printing of rolled and annealed nickel tapes. Crystallization was achieved by first annealing the a-Si film in contact with patterned Ni tape at 600°C for 20 min in a flowing forming gas (90 % N2, 10 % H2) environment, then removing the Ni tape and further annealing the a-Si film in vacuum for2hrsat600°C. An array of crystalline regions with diameters of up to 20 μm could be formed. Electron microscopy indicates that the regions are essentially single-crystalline except for the presence of twins and/or type A-B formations, and that all regions have the same orientation in all 3 directions even when separated by more than hundreds of microns. High resolution TEM analysis shows that formation of such orientation-controlled, nearly single crystalline regions is due to formation of nearly single crystalline NiSi2 under the point of contact, which then acts as the template for silicide-induced lateral crystallization. Furthermore, the orientation relationship between Si grains and Ni tape is observed to be Si (110) || Ni (001)

Gas-Phase Reactions

1981 ◽  
Author(s):  
Victor N. Kondratiev ◽  
Evgeniĭ E. Nikitin
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions
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