Kinetics of Dopant Metastability in a-Si:H

1992 ◽  
Vol 258 ◽  
Author(s):  
C. E. Nebel ◽  
R. A. Street ◽  
N. M. Johnson ◽  
W. B. Jackson
Keyword(s):  
Thermodynamic Equilibrium ◽  
Opposite Effect ◽  
Dark Conductivity ◽  
Electron Hole ◽  
Small Temperature ◽  
Stretched Exponential ◽  
Thermally Activated ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Stretched Exponential Decay

ABSTRACTSmall temperature-induced perturbations from thermodynamic equilibrium of doped hydrogenated amorphous silicon (a-Si:H) are explored by dark conductivity measurements. The equilibration kinetics reveal significant differences between phosphorus and boron doping. Raising the temperature leads to an increase of electron/hole densities which are related to the activation of additional dopants, while a decrease of temperature causes the opposite effect of dopant passivation. The creation kinetics of P doped a-Si:H is stretched exponential with a temperature independent β value of 0.85 whereas dopant passivation in the same temperature range is also stretched exponential decay, but with values for β < 0.8. In contrast, the kinetics of boron activation and passivation are stretched exponential with equal β values. The time constant τ to achieve thermodynamic equilibrium for both activation and passivation is thermally activated with energies ≃ 1.1 eV for P and B doped a-Si:H. τ depends weakly on the degree of perturbation. A discussion and interpretation of the data based on hydrogen migration in a-Si:H is given.

Isolation of Temperature Effects on the Kinetics of Light Induced Defect Generation in a-Si:H

1992 ◽  
Vol 258 ◽  
Author(s):  
L. Benatar ◽  
M. Grimbergen ◽  
A. Fahrenbruch ◽  
A. Lopez-Otero ◽  
D. Redfield ◽  
...  
Keyword(s):  
Defect Formation ◽  
Defect Density ◽  
Dark Conductivity ◽  
Stretched Exponential ◽  
Defect Generation ◽  
Thermally Activated ◽  
A Value ◽  
Effects Of Temperature ◽  
Kinetics Of

ABSTRACTData are presented here that show the effects of temperature on the kinetics of metastable defect formation in undoped a-Si:H over the range 45°-110°C. CPM (Constant Photocurrent Method), photoconductivity, and dark conductivity measurements were made and provide independent checks of the defect generation behavior. A stretched exponential description of defect formation as a function of time was used to fit the CPM defect density data. The stretched exponential time constant, τSE, is thermally activated with an apparent activation energy of 1 eV, a value that agrees well with data for defect anneal and solar cell degradation. The data indicate that thermal terms are not negligible for temperatures as low as 45°C, and therefore should be included in any model of the kinetics of defect formation. The role of adistribution of anneal energies and the regimes of dominance of thermal and optical rate terms are discussed in the context of the model.

Evolution of Charged Gap Statesin a- Si:H Under Light Exposure

2003 ◽  
Vol 762 ◽  
Author(s):  
M. Zeman ◽  
V. Nádaždy ◽  
R.A.C.M.M. van Swaaij ◽  
R. Durný ◽  
J.W. Metselaar
Keyword(s):  
Deep Level ◽  
Light Exposure ◽  
Dark Conductivity ◽  
Initial Energy ◽  
Energy Distributions ◽  
Transient Spectroscopy ◽  
Induced Changes ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Positively Charged

AbstractThe charge deep-level transient spectroscopy (Q-DLTS) experiments on undoped hydrogenated amorphous silicon (a-Si:H) demonstrate that during light soaking the states in the upper part of the gap disappear, while additional states around and below midgap are created. Since no direct correlation is observed in light-induced changes of the three groups of states that we identify from the Q-DLTS signal, we believe that we deal with three different types of defects. Positively charged states above midgap are related to a complex formed by a hydrogen molecule and a dangling bond. Negatively charged states below midgap are attributed to floating bonds. Various trends in the evolution of dark conductivity due to light soaking indicate that the kinetics of light-induced changes of the three gap-state components depend on their initial energy distributions and on the spectrum and intensity of light during exposure.

Low Temperature Kinetics for the Growth and Decay of Band-Tallcarriers and Dangling Bonds in Hydrogenated Amorphous Silicon

1999 ◽  
Vol 557 ◽  
Author(s):  
Niko Schultz ◽  
P.C. Taylor
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Underlying Mechanism ◽  
Total Production ◽  
Dangling Bonds ◽  
Band Tail ◽  
Thermally Activated ◽  
Spin Resonance ◽  
Hydrogenated Amorphous ◽  
Kinetics Of

AbstractIn hydrogenated amorphous silicon (a-Si:H), the kinetics of the light induced production of silicon dangling bonds and long-lived band-tail electrons and holes has been measured at temperatures between 65 and 340 K using light induced electron spin resonance (LESR). Below about 150 K the measurement of Si dangling bonds is masked by the accumulation of long-lived band-tail carriers. The kinetics of the growth and decay of these long-lived, trapped band-tail carriers consists of very fast components (τ < ms) and very long components (τ > h). Optical quenching of these long-lived carriers is not efficient at quenching energies of 0.6 eV. Afler removal of these long-lived band tail carriers by annealing at about 250 K we find that the total production of silicon dangling bonds at 65 K after 10 h of illumination is about a factor of five less than at 340 K. The dangling bond production resulting from 10 h of illumination is well fit to an underlying mechanism that, if thermally activated, exhibits an activation energy of approximately 10 meV.

On the stretched-exponential decay kinetics of the ionized DX centers in gallium doped Cd1−xMnxTe

2009 ◽  
Vol 404 (23-24) ◽  
pp. 5251-5254 ◽  
Author(s):  
J. Trzmiel ◽  
E. Placzek-Popko ◽  
A. Nowak ◽  
K. Weron ◽  
Z. Gumienny
Keyword(s):  
Exponential Decay ◽  
Decay Kinetics ◽  
Stretched Exponential ◽  
Dx Centers ◽  
Kinetics Of ◽  
Stretched Exponential Decay

Annealing the Defects in a-Si:H Under Illumination

1993 ◽  
Vol 297 ◽  
Author(s):  
Helena Gleskova ◽  
P.A. Morin ◽  
S. Wagner
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Deep Level ◽  
Hydrogenated Amorphous Silicon ◽  
Electron Hole ◽  
Single Carrier ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Hole Recombination

The results of a study of the kinetics of the light-induced annealing of the deep-level defects in hydrogenated amorphous silicon (a-Si:H) are presented. They show that at elevated temperatures illumination increases the rate of annealing compared to annealing in the dark. We also detected light-induced annealing at room temperature. On the basis of a model in which the defects are generated by electron-hole recombination and annealing occurs through the action of a single carrier, we found values of 0.86 eV for the activation energy of the light-induced generation coefficient γ-1, and 1.23 eV for the light-induced annealing prefactor λ

Hopping transport in doped co-deposited mixed-phase hydrogenated amorphous/nanocrystalline silicon thin films

2011 ◽  
Vol 1321 ◽  
Author(s):  
L. R. Wienkes ◽  
C. Blackwell ◽  
J. Kakalios
Keyword(s):  
Temperature Dependence ◽  
Electronic Transport ◽  
Nanocrystalline Silicon ◽  
Dark Conductivity ◽  
Mixed Phase ◽  
Dependence Analysis ◽  
Thermally Activated ◽  
Silicon Thin Films ◽  
And Shifts ◽  
Hydrogenated Amorphous

ABSTRACTStudies of the electronic transport properties of n-type doped hydrogenated amorphous/nanocrystalline silicon (a/nc-Si:H) films deposited in a dual-plasma co-deposition reactor are described. For these doped a/nc-Si:H, the conductivity increases monotonically for increasing crystal fractions up to 60% and displays marked deviations from a simple thermally activated temperature dependence. Analysis of the temperature dependence of the activation energy for these films finds that the dark conductivity is best described by a power-law temperature dependence, σ = σo (T/To)n where n = 1 – 4, suggesting multiphonon hopping as the main transport mechanism. These results suggest that electronic transport in mixed-phase films occurs through the a-Si:H matrix at lower nanocrystal concentrations and shifts to hopping conduction between clusters of nanocrystals at higher nanocrystal densities.

The Spectral Dependence of the Non-Radiative Efficiency in Hydrogenated Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
J. Fan ◽  
J. Kakalios
Keyword(s):  
Amorphous Silicon ◽  
Room Temperature ◽  
Hydrogenated Amorphous Silicon ◽  
Free Carrier ◽  
Radiative Efficiency ◽  
Sharp Minimum ◽  
Carrier Thermalization ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Heat Released

ABSTRACTThe room temperature non-radiative efficiency, defined as the ratio of the heat released per absorbed photon for doped and undoped hydrogenated amorphous silicon (a-Si:H) has been measured using photo-pyroelectric spectroscopy (PPES) for photon energies ranging from 2.5 to 1.6 eV. There is a fairly sharp minimum in the non-radiative efficiency when the a-Si:H is illuminated with near bandgap photons. We describe a model wherein this minimum arises from the variation in the amount of heat generated by free carrier thermalization as the incident photon energy is varied, and report measurements of the excitation kinetics of the non-radiative efficiency which support this proposal.

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