Optoelectronic Properties of High-Gap Amorphous Silicon-Carbon Alloys

1995 ◽  
Vol 377 ◽  
Author(s):  
V. Chu ◽  
J. P. Conde ◽  
P. Brogueira ◽  
P. Micaelo ◽  
J. P. Jarego ◽  
...  
Keyword(s):  
Carbon Content ◽  
Amorphous Silicon ◽  
Gas Flow ◽  
Room Temperature ◽  
Deposition Pressure ◽  
Hydrogen Dilution ◽  
Silicon Carbon ◽  
Recombination Centers ◽  
Hydrogenated Amorphous ◽  
Deposition Conditions

ABSTRACTThe dependence of the properties of hydrogenated amorphous silicon-carbon alloys deposited with a 1:10 silane (SiH4) to methane (CH4) or ethylene (C2H4) gas flow ratios with the hydrogen dilution, deposition pressure and power is studied. In methane-based films the carbon content shows a decrease (from ≈0.75 to 0.55) with increasing hydrogen dilution from 0 to 98%, while the ethylene-based films show no dependence of the carbon fraction (≈0.9) on hydrogen dilution. The photoconductivity shows an increase for hydrogen dilutions above 90= for both methane and ethylene-based films. While this increase is attributed, in the case of methane, to the observed decrease in carbon content, no corresponding decrease in carbon content is observed in the ethylene-based films, suggesting a decrease in the density of recombination centers with hydrogen dilution. The Urbach tail and the room-temperature photoluminescence peak correlate with carbon content independent of the carbon source-gas and deposition conditions used.

Amorphous Silicon-Carbon Alloys for Solar Cells

1993 ◽  
Vol 297 ◽  
Author(s):  
Yuan-Min Li
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Light Exposure ◽  
Open Circuit ◽  
Hydrogen Dilution ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous ◽  
Substrate Temperatures ◽  
Open Circuit Voltages

Recent efforts to optimize undoped, glow-discharge hydrogenated amorphous silicon-carbon alloys (a-SiC:H) with 1.9-2.0 eV bandgaps for solar cell applications are reviewed. Hydrogen dilution coupled with relatively low substrate temperatures (below 200 °C) have led to great improvements in the optical and phototransport properties of a-SiC:H films. The issue of alternative carbon feedstocks other than methane (CH4) will be explored. The improved a-SiC:H alloys have resulted in solar cells with high open circuit voltages (V∞ > 1.0 volt) and high fill factors (> 0.7). Further, the a-SiC:H solar cell instability upon prolonged light exposure has been much reduced. Correlation will be made between the properties of bulk undoped a-SiC:H films and the performance of p-i-nsingle junction solar cells using corresponding a-SiC:H thin i-layers.

Amorphous Silicon-Carbon Alloys and Amorphous Carbon from Direct Methane and Ethylene Activation by ECR

1997 ◽  
Vol 467 ◽  
Author(s):  
J. P. Conde ◽  
V. Chu ◽  
F. Giorgis ◽  
C. F. Pirrt ◽  
S. Arekat
Keyword(s):  
Carbon Source ◽  
Amorphous Silicon ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Chemical Vapor ◽  
Plasma Stream ◽  
Ecr Plasma ◽  
Silicon Carbon ◽  
Gas Flow Ratio ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-carbon alloys are prepared using electron-cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition. Hydrogen is introduced into the source resonance cavity as an excitation gas. Silane is introduced in the main chamber in the vicinity of the plasma stream, whereas the carbon source gases, methane or ethylene, are introduced either with the silane or with the hydrogen as excitation gases. The effect of the type of carbon-source gas, excitation gas mixture and silane-to-carbon source gas flow ratio on the deposition rate, bandgap, subgap density of states, spin density and hydrogen evolution are studied.

Recombination Process in the As-Deposited State of Hydrogenated Amorphous Silicon

1993 ◽  
Vol 297 ◽  
Author(s):  
Jong-Hwan Yoon
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Energy Levels ◽  
Hydrogenated Amorphous Silicon ◽  
Recombination Process ◽  
Defect States ◽  
Deep Defect ◽  
Recombination Centers ◽  
Hydrogenated Amorphous ◽  
Deposition Conditions

Intrinsic deep defect-related recombination process has been studied in a series of undoped hydrogenated amorphous silicon(a-Si:H) films grown under different deposition conditions. Steady-state photoconductivity (σph) was measured as a function of deep defect density Nd, Urbach energy Eu, and dark Fermi energy Ef. It was found that σph strongly depends on these parameters while Ef- stays at the energy levels lower than 0.82 eV below Ec, but it is nearly independent of those while Ef stays at above 0.82 eV. These behaviors were found to be independent of the sample deposition conditions. These results indicates that subgap defect states enclosed by E=0.82 eV and Ef are the dominant recombination centers.

scholarly journals Sputtered Non-Hydrogenated Amorphous Silicon as Alternative Absorber for Silicon Photovoltaic Technology

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6550
Author(s):  
Susana Fernández ◽  
J. Javier Gandía ◽  
Elías Saugar ◽  
Mª Belén Gómez-Mancebo ◽  
David Canteli ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Structural Changes ◽  
Continuous Wave ◽  
Low Cost ◽  
Hydrogenated Amorphous Silicon ◽  
Amorphous Structure ◽  
Gas Pressure ◽  
Hydrogenated Amorphous ◽  
Deposition Conditions

Non-hydrogenated amorphous-silicon films were deposited on glass substrates by Radio Frequency magnetron sputtering with the aim of being used as precursor of a low-cost absorber to replace the conventional silicon absorber in solar cells. Two Serie of samples were deposited varying the substrate temperature and the working gas pressure, ranged from 0.7 to 4.5 Pa. The first Serie was deposited at room temperature, and the second one, at 325 °C. Relatively high deposition rates above 10 Å/s were reached by varying both deposition temperature and working Argon gas pressure to ensure high manufacturing rates. After deposition, the precursor films were treated with a continuous-wave diode laser to achieve a crystallized material considered as the alternative light absorber. Firstly, the structural and optical properties of non-hydrogenated amorphous silicon precursor films were investigated by Raman spectroscopy, atomic force microscopy, X-ray diffraction, reflectance, and transmittance, respectively. Structural changes were observed in the as-deposited films at room temperature, suggesting an orderly structure within an amorphous silicon matrix; meanwhile, the films deposited at higher temperature pointed out an amorphous structure. Lastly, the effect of the precursor material’s deposition conditions, and the laser parameters used in the crystallization process on the quality and properties of the subsequent crystallized material was evaluated. The results showed a strong influence of deposition conditions used in the amorphous silicon precursor.

Room temperature optical bistability in hydrogenated amorphous silicon-carbon alloys

1993 ◽  
Vol 88 (8) ◽  
pp. 579-581
Author(s):  
Kunji Chen ◽  
Jun Xu ◽  
Xinfan Huang ◽  
Duan Feng ◽  
Dakui Zhuang ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Optical Bistability ◽  
Room Temperature ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous

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.

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