Steady-State Photoconductivity in Undoped Amorphous Silicon

1989 ◽  
Vol 149 ◽  
Author(s):  
Jeffrey Zhaohuai Liu ◽  
S. Wagner
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Steady State ◽  
Amorphous Silicon ◽  
Thermal Activation ◽  
Hydrogenated Amorphous Silicon ◽  
Thermal Activation Energy ◽  
Strong Temperature Dependence ◽  
Quasi Fermi Level ◽  
Hydrogenated Amorphous

ABSTRACTAn analytical expression for the thermal activation energy of the steady-state photoconductivity is shown to agree with experimental data in a range of temperature and generation rate for undoped hydrogenated amorphous silicon (a-Si:H). This agreement supports our suggestion that the commonly observed small activation energy of the photoconductivity in undoped a-Si:H originates in the strong temperature dependence of the quasi-Fermi level for electrons.

Dependence of Steady-State Defect Density in Hydrogenated Amorphous Silicon on Carrier Generation Rate Studied Over a Wide Range

1993 ◽  
Vol 297 ◽  
Author(s):  
Nobuhiro Hata ◽  
Gautam Ganguly ◽  
Akihisa Matsuda
Keyword(s):  
Steady State ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Continuous Light ◽  
Effective Rate ◽  
Defect States ◽  
Carrier Generation ◽  
Wide Range ◽  
Hydrogenated Amorphous

Measurements of the steady-state defect density (Nst) in hydrogenated amorphous silicon under illumination of pulse-laser light, as well as of continuous light, were carried out; and the dependence of Nst on the effective rate of carrier generation (G) is presented. The values of G ranged from 8 x 1021 to 2.4 × 1023 cm-3 s-1, while the illumination temperature was kept at 30 °C or at 105 °C. The results showed trends of Nst increasing with G similarly to the trends in the literature, but covered a higher and wider G range, and fitted a defect model which assumes a limited number of possible defect states.

New Model for “Stretched Exponential” Relaxation

1996 ◽  
Vol 420 ◽  
Author(s):  
Chris G. Van De Walle
Keyword(s):  
Experimental Data ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Statistical Distributions ◽  
New Model ◽  
Stretched Exponential ◽  
Careful Treatment ◽  
Exponential Relaxation ◽  
Hydrogenated Amorphous

AbstractA new model to explain stretched exponential relaxation in hydrogenated amorphous silicon is presented. The model does not invoke statistical distributions; rather, it is based on a careful treatment of diffusion, including retrapping. Excellent fits to a variety of experimental data are obtained.

Toward a Practical Model of a-Si:H Defects in Intensity-Time-Temperature Space

1994 ◽  
Vol 336 ◽  
Author(s):  
D. Caputo ◽  
J. Bullock ◽  
H. Gleskova ◽  
S. Wagner
Keyword(s):  
Light Intensity ◽  
Fermi Level ◽  
Amorphous Silicon ◽  
Thermal Annealing ◽  
Hydrogenated Amorphous Silicon ◽  
Defect States ◽  
Quasi Fermi Level ◽  
Practical Model ◽  
Density Of Defect States ◽  
Hydrogenated Amorphous

ABSTRACTIn this paper we develop a model of the defect kinetics in hydrogenated Amorphous silicon (a:Si:H) with the goal of predicting the density of defect states g (E) established by any given light intensity I, for arbitrary times t and temperatures T. While we build on widely accepted expressions for the the rates of light-induced and thermal annealing, we examine in more detail the light induced annealing (LIA) term. The model shows that the LIA process can be described with the thermal annealing term if a suitable reduction to the annealing energy is introduced. This reduction depends on the light intensity such as to suggest a relation to the shift of the electron quasi-Fermi level under illumination.

Photoelectronic Properties of a-Si:Sex and a-Si:Tex Thermally Evaporated Films.

1986 ◽  
Vol 70 ◽  
Author(s):  
F. G. Wakim
Keyword(s):  
Activation Energy ◽  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Thermal Activation ◽  
Thermal Activation Energy ◽  
Dangling Bonds ◽  
Optical Gap ◽  
Si Films

ABSTRACTThe presence of selenium (Se) or Telurium (Te) in amorphous silicon films seems to improve the quality of these films by reducing the number of unsatisfied or dangling bonds and changing the optical gap and thermal activation energy. The thermal activation energies of a-Si:Sex and a-Si:Tex were always larger than that of a-Si films. The measured optical gap can be tailored to some value between 0.8 eV and 1.8 eV depending on the use of Se or Te and on the relative concentrations. The presence of Se or Te in a-Si films seems to have the same effect as that of hydrogen in a-Si films prepared by glow discharge of silane and used in solar cells.

Changes of Drift Mobility in a-Si:H with Light Exposure and Doping

1987 ◽  
Vol 95 ◽  
Author(s):  
J. Takada ◽  
H. Fritzsche
Keyword(s):  
Light Intensity ◽  
Amorphous Silicon ◽  
Light Exposure ◽  
Hydrogenated Amorphous Silicon ◽  
Drift Mobility ◽  
Mobility Edge ◽  
Strong Light ◽  
Quasi Fermi Level ◽  
Multiple Trapping ◽  
Hydrogenated Amorphous

AbstractMeasurements of the drift mobility μ of photo-excited electrons in n-type hydrogenated amorphous silicon (a-Si:H) as a function of light intensity are reported. The value of μ increases as the quasi Fermi level is moved closer to the transport states in accordance with the multiple trapping theory. The drift mobility decreases with increasing doping as well as with an increase in the concentration of metastable dangling bonds defects by strong light exposures. This decrease in μ between 300 and 360K can be explained by a corresponding decrease in the microscopic mobility, by an increase in the density of tail states within 0.35eV below the electron mobility edge, or by a combination of both these effects.

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