Assessment of Weak Si-Si Bond Breaking Mechanisms of the Staebler-Wronski Effect

1991 ◽  
Vol 219 ◽  
Author(s):  
R. Biswas ◽  
I. Kwon ◽  
C. M. Soukoulis
Keyword(s):  
Interatomic Potential ◽  
Bond Breaking ◽  
Dangling Bond ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Excited Carrier ◽  
Carrier Energy ◽  
The Stability ◽  
Staebler Wronski Effect ◽  
New Si

ABSTRACTThe mechanisms of the Staebler-Wronski effect are investigated by examining the stability of computer-generated amorphous hydrogenated silicon networks with a molecular dynamics approach. Models with both monohydride and dihydride species are examined. A new Si-H interatomic potential is utilized for the simulations. A localized excitation is used to model the non-radiative transfer of photo-excited carrier energy to the lattice. The a-Si:H model with only monohydride species is stable to bond-breaking excitations. The a-Si:H model with both monohydride and dihydride species is less stable and exhibits, after local excitations, higher energy dangling bond states that can however be easily annealed away.

Search for Explaining the Staebler-Wronski Effect

1997 ◽  
Vol 467 ◽  
Author(s):  
H. Fritzsche ◽  
Tucson Az
Keyword(s):  
Spatial Correlation ◽  
Long Range ◽  
Photon Energy ◽  
Structural Changes ◽  
Hydrogen Diffusion ◽  
Critical Value ◽  
Bond Breaking ◽  
Dangling Bond ◽  
High Fields ◽  
Staebler Wronski Effect

ABSTRACTFor twenty years we searched to understand the Staebler-Wronski effect (SWE). New results continue to emerge which invalidate prior interpretations. Recent evidence shows that the SWE is not associated with impurities. Long-range hydrogen diffusion is ruled out because the SWE occurs with comparable efficiency between 400K and the lowest temperatures. Nonradiative geminate recombinations might be important since high fields reduce the SWE significantly. It disappears when the bandgap or the photon energy falls below a critical value. The creation of a metastable density of dangling bond defects has been considered to be its sole manifestation. However, there is mounting evidence for light-induced structural changes which extend throughout the material. The weak bond breaking model emerges as the only viable explanation of the SWE if the expected spatial correlation between defects and hydrogen is destroyed by subsequent recombination events. The SWE is reduced by a favorable microstructure and low hydrogen content. It is suggested that defect pairs have larger recombination coefficients than isolated defects.

Effect of the Substrate Temperature on the Transition from Amorphous to Microcrystalline Silicon with High Hydrogen Dilution

2013 ◽  
Vol 773 ◽  
pp. 520-523
Author(s):  
Ming Liang Zhang ◽  
Hui Dong Yang ◽  
Kai Zhao Yang
Keyword(s):  
Substrate Temperature ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Microcrystalline Silicon ◽  
High Hydrogen ◽  
Hydrogenated Silicon ◽  
Glass Substrates ◽  
Amorphous Hydrogenated Silicon ◽  
The Stability

Transition films of amorphous hydrogenated silicon (a-Si:H) to microcrystalline silicon (μc-Si:H) have attracted much attention due to the stability, high overall quality for solar cells configuration. Hydrogenated amorphous and microcrystalline silicon films were deposited on glass substrates by a conventional plasma enhanced chemical vapor deposition (PEVCD) varying the substrate temperature from 275 to 350 °C. A silane concentration of 4% and a total flow rate of 100 sccm were used at a gas pressure of 267 Pa. The film thicknesses of the prepared samples were between 700 and 900 nm estimated from the optical transmission spectra. The deposition rates were between 0.2 and 0.3 nm/s. The phase composition of the deposited silicon films were investigated by Raman spectroscopy. The transition from amorphous to microcrystalline silicon was found at the higher temperatures. The crystallization process of the amorphous silicon can be affected by the substrate temperature. A narrow structural transition region was observed from the changes of the crystalline volume fraction. The dark electrical conductivity of the silicon films increased as the substrate temperature increasing.

The Dangling Bond in Undoped Amorphous Hydrogenated Silicon: Trap or Recombination Center?

1986 ◽  
Vol 70 ◽  
Author(s):  
M. A. Parker ◽  
K. A. Conrad ◽  
E. A. Schiff
Keyword(s):  
Experimental Data ◽  
Response Time ◽  
Electrical Contacts ◽  
Electron Trap ◽  
Recombination Center ◽  
Photocurrent Response ◽  
Dangling Bond ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon

ABSTRACTThe role of the neutral dangling bond defect upon photocarrier processes in undoped amorphous hydrogenated silicon (a-Si:H) is discussed. The evidence that the dangling bond is a simple recombination center is reviewed, and it is shown that this model does not account for photocurrent response time measurements. Experimental data pertinent to the role of electrical contacts upon response time measurements are presented, and it is concluded that contact effects do not account for response-time measurements. The possibility that the dangling bond is primarily an electron trap is discussed.

Microstructure and Dangling Bond Defects in Amorphous Hydrogenated Silicon Deposited Near Room Temperature

1992 ◽  
Vol 258 ◽  
Author(s):  
Man Ken Cheung ◽  
Mark A. Petrich
Keyword(s):  
Room Temperature ◽  
Dangling Bond ◽  
Optimum Conditions ◽  
Band Tail ◽  
Hydrogenated Silicon ◽  
Photothermal Deflection Spectroscopy ◽  
Amorphous Hydrogenated Silicon ◽  
Photothermal Deflection ◽  
Substrate Temperatures ◽  
Absorption Measurements

ABSTRACTThe microstructure of high-density amorphous hydrogenated silicon (a-S.i:H) films deposited at 50°C substrate temperature was revealed by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies to be similar to that of “device-quality” a-Si:H films deposited at standard “optimum” conditions. However, optical absorption measurements of these low microstructure 50°C films with photothermal deflection spectroscopy indicate that they have higher densities of gap state defects and localized band tail states than “device-quality” films deposited at standard substrate temperatures. The correlation between the amount of microstructure and electronic properties is not unique. A low amount of microstructure is a necessary, but not sufficient, requirement for high electronic quality a-Si:H films.

Optically Induced Paramagnetism in Amorphous Hydrogenated Silicon Nitride Thin Films

1992 ◽  
Vol 242 ◽  
Author(s):  
W. L. Warren ◽  
J. Kanicki ◽  
F. C. Rong ◽  
W. R. Buchwald ◽  
M. Harmatz
Keyword(s):  
Thin Films ◽  
Silicon Nitride ◽  
Ultra Violet ◽  
Dangling Bond ◽  
Hydrogenated Silicon ◽  
Uv Illumination ◽  
Defect Centers ◽  
Amorphous Hydrogenated Silicon ◽  
The Creation ◽  
A Charge

ABSTRACTThe creation mechanisms of Si and N dangling bond defect centers in amorphous hydrogenated silicon nitride thin films by ultra-violet (UV) illumination are investigated. The creation efficiency and density of Si centers in the N-rich films are independent of illumination temperature, strongly suggesting that the creation mechanism of the spins is electronic in nature, i.e., a charge transfer mechanism. However, our results suggest that the creation of the Si dangling bond in the Si-rich films are different. Last, we find that the creation of the N dangling-bond in N-rich films can be fit to a stretched exponential time dependence, which is characteristic of dispersive charge transport.

Amorphous Hydrogenated Silicon P-I-N Solar Cells Grown from Hydrogen-Diluted Silane

1990 ◽  
Vol 192 ◽  
Author(s):  
Murray S Bennett ◽  
Jacob C Tu
Keyword(s):  
Solar Cells ◽  
Deposition Pressure ◽  
Hydrogenated Silicon ◽  
Hydrogen Dilution ◽  
Amorphous Hydrogenated Silicon ◽  
Deposition Parameters ◽  
Wide Range ◽  
The Stability ◽  
Made In ◽  
Deposition Conditions

ABSTRACTWe investigated p-i-n solar cells in which the i-layer was grown from hydrogen-diluted silane. The deposition parameters which were varied include flow rates, deposition pressure and power, and the degree of hydrogen dilution. We found that high quality devices could be made in which the i-layer was grown under a wide range of deposition conditions but that over this range neither the initial performance nor the stability of the devices differed significantly from those of cells having the same structure, but in which the i-layer was deposited from SiH4 with no H2-dilution.

Dangling bond in amorphous hydrogenated silicon: Anomalous spin relaxation

1986 ◽  
Vol 34 (3) ◽  
pp. 1415-1421 ◽  
Author(s):  
U. Vahalia ◽  
J. Ferrario ◽  
E. A. Schiff
Keyword(s):  
Spin Relaxation ◽  
Dangling Bond ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon
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