Contributions of D0 and non-D0 Gap States to the Kinetics of Light Induced Degradation of Amorphous Silicon under 1 sun Illumination

2001 ◽  
Vol 664 ◽  
Author(s):  
J. Pearce ◽  
X. Niu ◽  
R. Koval ◽  
G. Ganguly ◽  
D. Carlson ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Degradation Kinetics ◽  
Hydrogen Dilution ◽  
Spin Resonance ◽  
The Creation ◽  
Staebler Wronski Effect ◽  
Gap States ◽  
Induced Changes ◽  
Induced Defects ◽  
Hydrogenated Amorphous

ABSTRACTLight induced changes to 1 sun degraded steady state (DSS) have been investigated on hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells and corresponding films fabricated with and without hydrogen dilution of silane. Striking similarities are found for the degradation kinetics, between the electron mobility lifetime (μτ) products and the corresponding fill factors (FF). These correlations that exist for both intrinsic materials at temperatures between 25 and 100°C, are present for the DSS as well as in the kinetics, which exihibit distinctly different dependence on temperature. No such correlations are present between μτ, FF and densities of D0 defects, measured with subgap absorption α(E) at 1.2eV, and electron spin resonance (ESR). The creation of non-D0 defects is also clearly indicated by the temperature dependence of the kinetics and the changes in the shape of α(E) with the results suggesting the presence of more than one mechanism for the creation of light induced defects associated with the Staebler-Wronski effect (SWE).

Stability in Amorphous Silicon

1987 ◽  
Vol 95 ◽  
Author(s):  
Z E. Smith ◽  
S. Wagner
Keyword(s):  
Electron Spin Resonance ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Thermal Recovery ◽  
Defect States ◽  
Spin Resonance ◽  
Resonance Data ◽  
Electron Spin Resonance Data ◽  
Gap States ◽  
Hydrogenated Amorphous

AbstractThe experimental phenomena associated with light-induced degradation and thermal recovery of hydrogenated amorphous silicon (a-Si:H) films are reviewed, with special emphasis on the limitations of each experimental technique. When several techniques are used in concert, a fuller picture emerges. Recent experiments suggest different positions in the band-gap of the paramagnetic-associated defect states (the dangling bonds) for doped and undopedfilms; this information can be combined with conductivity, sub-bandgap optical absorption and electron spin resonance data to yield a model for the density of gap states (DOS) in a- Si:H, including how the DOS changes upon illumination and annealing.

Evolution of D0 and non-D0 Light Induced Defect States in a-Si:H Materials and Their Respective Contribution to Carrier Recombination

2004 ◽  
Vol 808 ◽  
Author(s):  
J. M. Pearce ◽  
J. Deng ◽  
V. Vlahos ◽  
R. W. Collins ◽  
C. R. Wronski ◽  
...  
Keyword(s):  
Room Temperature ◽  
Defect States ◽  
Carrier Recombination ◽  
Spin Resonance ◽  
Respective Contribution ◽  
Gap States ◽  
Induced Changes ◽  
Induced Defects ◽  
Kinetics Of ◽  
Absorption Measurements

A study has been carried out on the evolution of light induced defects in protocrystalline (diluted) a-Si:H films under 1 sun illumination. A room temperature reversal is observed in the photocurrents at 25°C, which is consistent with the relaxation in the recombination currents on corresponding p-i-n solar cells. It is also consistent with the pressure of “fast” states such as have been observed after high intensity illumination. Even with the limitations imposed by the relaxation in the light induced changes on the subgap absorption measurements, the evolution of distinctly different gap states centered around 0.9 and 1.15eV from the conduction band was identified. The kinetics of the electron occupied states, kN(E), at these two energies is compared with that of the neutral dangling bond (D0) densities as measured with electron spin resonance. Because of the similarity between the preliminary results of these kinetics it has not been possible to identify which states correspond to the D0 nor to draw any reliable conclusions about the nature of the different states.

Tritium Induced Defects in Amorphous Silicon

2004 ◽  
Vol 808 ◽  
Author(s):  
J. Whitaker ◽  
J. Viner ◽  
S. Zukotynski ◽  
E. Johnson ◽  
P.C. Taylor ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Defect Production ◽  
Photothermal Deflection Spectroscopy ◽  
Spin Resonance ◽  
Photothermal Deflection ◽  
Induced Defects ◽  
Hydrogenated Amorphous ◽  
Accumulation Of Defects ◽  
Insight Into

ABSTRACTWe report the growth of tritium induced defects in tritium doped hydrogenated amorphous silicon (a-Si:H,T) as measured by electron spin resonance (ESR) and photothermal deflection spectroscopy (PDS). The measurements allow one to examine the accumulation of defects in a-Si:H,T where the defect production mechanism is known. Defects produced by tritium decay are found to be much less numerous than the number of decayed tritium atoms and they are metastable like Staebler-Wronski defects. These results provide new insight into the metastable defect creation and the role of hydrogen motion.

Light Induced Changes in PIN Solar Cells: Beyond the Staebler-Wronski Effect

2012 ◽  
Vol 1426 ◽  
pp. 57-62
Author(s):  
Ka-Hyun Kim ◽  
Erik V. Johnson ◽  
Samir Kasouit ◽  
Pere Roca i Cabarrocas
Keyword(s):  
Solar Cells ◽  
Structural Changes ◽  
Hydrogen Diffusion ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Interface Delamination ◽  
Absorbing Layer ◽  
Staebler Wronski Effect ◽  
Induced Changes ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated polymorphous silicon (pm-Si:H) is one of the most promising candidates for a stable top cell material in multi-junction thin film solar cells. Solar cells using pm-Si:H as their absorbing layer show very interesting degradation kinetics when compared to hydrogenated amorphous silicon (a-Si:H), summarized by macroscopic structural changes and irreversible changes in solar cell characteristics, while nevertheless preserving a higher stabilized efficiency. Notably, pm-Si:H solar cells, once degraded, respond to neither annealing nor further light-soaking. Such results suggest a device degradation mechanism including structural changes, active hydrogen motion, and interface delamination mediated by fast hydrogen diffusion and accumulation at the interface. Interestingly, a similar behavior was reported for a-Si:H solar cells under severe light soaking conditions (at 350 °C or under 50 suns) while pm-Si:H solar cells show such behavior under 1 sun at 40 °C.

Microscopic Aspects of the Staebler-Wronski Effect

1997 ◽  
Vol 467 ◽  
Author(s):  
Martin Stutzmann
Keyword(s):  
Continuous Wave ◽  
Quantitative Description ◽  
Low Field ◽  
Spin Dependent Transport ◽  
Spin Resonance ◽  
Electron Hole Pair ◽  
Dependent Transport ◽  
Staebler Wronski Effect ◽  
Induced Defects ◽  
Hydrogenated Amorphous

ABSTRACTThe microscopic origin and the creation mechanisms of metastable, light-induced defects in hydrogenated amorphous silicon are reviewed. Based on excitonic electron-hole pair recombination, a consistent quantitative description of defect creation kinetics can be obtained, including the experimentally observed differences between continuous wave and pulsed illumination as well as the effect of competing recombination pathways in compensated material. High resolution spin resonance spectra obtained by low-field spin-dependent transport are used to examine the interaction of metastable defects with hydrogen.

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.

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

2012 ◽  
Vol 184 ◽  
pp. 416-421 ◽  
Author(s):  
H. Mizubayashi ◽  
I. Sakata ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Wide Distribution ◽  
Activation Energies ◽  
Mechanical Spectroscopy ◽  
Induced Changes ◽  
Mild Temperature ◽  
Hydrogenated Amorphous

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

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