Bandgap Engineering in Hydrogenated Silicon Films Made by Combined Hydrogen Dilution and Atomic Hydrogen Treatments

1993 ◽  
Vol 297 ◽  
Author(s):  
K.C. Hsu ◽  
H.L. Hwang
Keyword(s):  
Line Shape ◽  
Atomic Hydrogen ◽  
Nmr Spectra ◽  
Hydrogen Treatment ◽  
Dilution Ratio ◽  
Bandgap Engineering ◽  
Sharp Line ◽  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Lower Temperature

Effective bandgap modifications of hydrogenated silicon are demonstrated in this work. These films were obtained by (combined) hydrogen dilution and atomic hydrogen treatments during the deposition. The Si—H bonding configurations were characterized by NMR measurements. The hydrogen dilution tends to create a very sharp line-shape in the NMR spectra as the dilution ratio is increased and the addition of atomic hydrogen treatment can produce the same NMR spectra even at a lower temperature. The optical bandgap of these Si:H samples showed the same tendency that the bandgap narrowed as both the dilution ratio was increased and the addition of atomic hydrogen treatment.

Effects of Diluted-Hydrogen and Hydrogen-Atom-Treatment on the Silicon-Hydrogen Bonding Configurations of Hydrogenated Silicon Films

1992 ◽  
Vol 283 ◽  
Author(s):  
K. C. Hsu ◽  
H. Chang ◽  
H. L. Hwang
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Nmr Spectra ◽  
Silicon Films ◽  
Degree Of Crystallinity ◽  
Hydrogen Treatment ◽  
Hydrogenated Silicon ◽  
Bonding Configuration ◽  
Raman Scattering Spectra

ABSTRACTThe silicon—hydrogen bonding configuration studies of hydrogenated silicon films that were fabricated by diluted—hydrogen and hydrogen—atom—treatment methods are presented. The diluted—hydrogen samples tend to show a very sharp line—shape in the NMR spectra as the H2/SiH4 dilution ratio is increased and/or temperature is elevated. The addition of atomic hydrogen treatment can produce the same NMR spectra at a temperature lower than 200°C. The Raman scattering spectra show that the μc—Si phase can be formed by the atomic hydrogen treatment. The infrared absorption spectra also indicate an increase of SiH2 bonding configuration and a hydrogen content reduction when atomic hydrogen treatment is employed. These results suggest that the degree of crystallinity of hydrogenated silicon films can be systematically adjusted.

Bandgap Engineering of Amorphous Hydrogenated Silicon Carbide

MRS Advances ◽  
2016 ◽  
Vol 1 (43) ◽  
pp. 2929-2934 ◽  
Author(s):  
J. A. Guerra ◽  
L. M. Montañez ◽  
K. Tucto ◽  
J. Angulo ◽  
J. A. Töfflinger ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Urbach Energy ◽  
Amorphous Material ◽  
Deposition Process ◽  
Bandgap Energy ◽  
Bandgap Engineering ◽  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Amorphous Hydrogenated Silicon ◽  
Proposed Model

ABSTRACTA simple model to describe the fundamental absorption of amorphous hydrogenated silicon carbide thin films based on band fluctuations is presented. It provides a general equation describing both the Urbach and Tauc regions in the absorption spectrum. In principle, our model is applicable to any amorphous material and it allows the determination of the bandgap. Here we focus on the bandgap engineering of amorphous hydrogenated silicon carbide layers. Emphasis is given on the role of hydrogen dilution during the deposition process and post deposition annealing treatments. Using the conventional Urbach and Tauc equations, it was found that an increase/decrease of the Urbach energy produces a shrink/enhancement of the Tauc-gap. On the contrary, the here proposed model provides a bandgap energy which behaves independently of the Urbach energy.

13C NMR-spektroskopische Untersuchungen an Äthylaluminiumverbindungen / 13C NMR Spectroscopic Investigations of Ethylaluminium Compounds

1976 ◽  
Vol 31 (6) ◽  
pp. 730-736 ◽  
Author(s):  
R. Rottler ◽  
C. G. Kreiter ◽  
G. Fink
Keyword(s):  
Temperature Dependence ◽  
Exchange Reaction ◽  
13C Nmr ◽  
Line Shape ◽  
Nmr Spectra ◽  
Exchange Process ◽  
Kcal Mole ◽  
Line Shapes ◽  
Calculated Line ◽  
C Nmr

The 13C NMR spectra of the ethylaluminium compounds [Al(C2H5)xCl3_x]2 x = 1, 1,5, 2 and 3 are presented and factors governing the temperature dependence of the line shape are discussed. The exchange reaction of terminal ethyl groups for chlorine ligands and ethyl ligands, resp., in ethylaluminium-sesquichloride was investigated by fitting the calculated line shapes to the observed spectra.The energy of activation of this exchange process was determined as to be 12,3 ‡ 1,5 kcal/mole. The synthesis of 13C2-[Al(C2H5)Cl2]2 is described.

Structure and Optoelectronic Properties as a Function of Hydrogen Dilution of Micro-Crystalline Silicon Films Prepared by Hot Wire Chemical Vapor Deposition

1999 ◽  
Vol 557 ◽  
Author(s):  
Guozhen Yue ◽  
Jing Lin ◽  
Qi Wang ◽  
Daxing Han
Keyword(s):  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Peak Position ◽  
Initial Growth ◽  
Hot Wire ◽  
Dilution Ratio ◽  
Structure Transition ◽  
Transparent Substrate ◽  
Hydrogen Dilution ◽  
Substrate Side

AbstractFilms prepared by hot wire CVD using H dilution ratio, R=H 2/SiH4, from 1 to 20 were studied by X-ray, Raman, PL, and conductivity measurements. We found that (a) when the dilution ratio reached R=3, the structure transition from amorphous to microcrystalline growth occured; meanwhile, PL spectrum showed a dual-peak at 1.3 and 1.0 eV; (b) the total intensity, band width, and peak position of the low energy PL band decreased with increasing H dilution; (c) both the Raman and PL measured from the transparent substrate side showed that initial growth tends to be amorphous and a portion of μc-Si was formed when R ≥ 5; and (d) the conductivity activation energy first decreased from 0.68 to 0.15 eV when the film transition from a- to μc-Si; then increased slightly with increasing μc-Si fraction. The results demonstrate that the variation of the H-dilution ratio has significant effects on both the film structures and the optoelectric properties.

Bombardment by Reflection - A Novel Method to Prepare High Quality Hydrogenated Amorphous Germanium by Anodic PCVD

1997 ◽  
Vol 467 ◽  
Author(s):  
Annette Diez ◽  
Twlo P. Drüsedau
Keyword(s):  
Atomic Hydrogen ◽  
Carrier Mobility ◽  
Hydrogen Pressure ◽  
Amorphous Germanium ◽  
Hydrogen Dilution ◽  
Novel Method ◽  
Hydrogenated Amorphous ◽  
Hydrogenated Amorphous Germanium ◽  
Kinetics Of

ABSTRACTDeposition of amorphous germanium by anodic PCVD was performed changing the germane/hydrogen dilution ratio from 1/6 to 1/100. Films deposited under high dilution of germane are of a high mechanical density (92.5 % of bulk) and good optoelectronic properties (electrical conductivity at room temperature σ=10−5 (Ω cm)−1, majority carrier mobility-lifetime product at λ=1200 nm ημ=x 10−7 cm2/V). The quality of the films is increased by deposition at increasing pumping speed for hydrogen (lower hydrogen pressure) keeping the other parameters constant. It is suggested that fast atomic hydrogen originating from a backscattering process at the powered electrode bombard the growing film and contribute to the improved quality of the a-Ge:H. Also, the growth kinetics of the films is changed from linear to parabolic dependence on germane flow interchanging deposition from high to low hydrogen pressure. This effect is rationalized in terms of a contribution of energetic atomic hydrogen to the dissociation of germane.

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