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.

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.

Drift mobility under single and double injection in hydrogenated amorphous silicon

1988 ◽  
Vol 57 (6) ◽  
pp. 715-720 ◽  
Author(s):  
L. Xu ◽  
G. Winborne ◽  
M. Silver ◽  
V. Cannella ◽  
J. Mcgill
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Drift Mobility ◽  
Double Injection ◽  
Hydrogenated Amorphous

Kinetics of Growth and Recovery of Light-Induced Defects Under High-Intensity Illumination

1992 ◽  
Vol 258 ◽  
Author(s):  
Masao Isomura ◽  
Sigurd Wagner
Keyword(s):  
Light Intensity ◽  
Amorphous Silicon ◽  
High Intensity ◽  
Hydrogenated Amorphous Silicon ◽  
Increased Sensitivity ◽  
Induced Defects ◽  
Hydrogenated Amorphous ◽  
Kinetics Of ◽  
Diffusion Of Hydrogen

ABSTRACTWe report a study of the rates of generation and of annealing of the light-induced defects in hydrogenated amorphous silicon (a-Si:H). The rates of generation are found to be sensitive to temperature when the light intensity is high. This increased sensitivity to temperature at high rates suggests that a temperature-activated process such as hydrogen motion controls the rates of generation more when they are high. The rate of annealing at 130°C is strongly accelerated by illumination, and depends strongly on the light intensity. This may be explained by the diffusion of hydrogen, accelerated by excess carriers.

The Movement of Mobility Edges in Hydrogenated Amorphous Silicon

1990 ◽  
Vol 192 ◽  
Author(s):  
S. Lee ◽  
D. Heller ◽  
C. R Wronski
Keyword(s):  
Amorphous Silicon ◽  
Electron Mobility ◽  
Hydrogenated Amorphous Silicon ◽  
Hole Mobility ◽  
The Other ◽  
High Quality ◽  
Electrical Field ◽  
Mobility Edge ◽  
Internal Photoemission ◽  
Hydrogenated Amorphous

ABSTRACTInternal photoemission of both electrons and holes is used to investigate the movement of the mobility edges in high quality intrinsic, undoped hy-drogenated amorphous silicon (a-Si:H) with temperature and electrical field. The electron mobility edge is found to move up in energy by ∼40meV between 298K and 120K. On the other hand, the hole mobility edge remains essentially unchanged between 298K and 160K. The injection (and collection) of photoemitted holes is less efficient than that for electrons and in the films studied could not be measured below 160K.

scholarly journals Hole Drift Mobility Measurements on a-Si:H using Surface and Uniformly Absorbed Illumination

2009 ◽  
Vol 1153 ◽  
Author(s):  
Steluta Adriana Dinca ◽  
Eric A Schiff ◽  
Subhendu Guha ◽  
Baojie Yan ◽  
Jeff Yang
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Time Of Flight ◽  
Drift Mobility ◽  
Electrode Interface ◽  
Steel Substrates ◽  
Hydrogenated Amorphous ◽  
Time Of Flight Method

AbstractThe standard, time-of-flight method for measuring drift mobilities in semiconductors uses strongly absorbed illumination to create a sheet of photocarriers near an electrode interface. This method is problematic for solar cells deposited onto opaque substrates, and in particular cannot be used for hole photocarriers in hydrogenated amorphous silicon (a Si:H) solar cells using stainless steel substrates. In this paper we report on the extension of the time-of-flight method that uses weakly absorbed illumination. We measured hole drift-mobilities on seven a Si:H nip solar cells using strongly and weakly absorbed illumination incident through the n-layer. For thinner devices from two laboratories, the drift-mobilities agreed with each other to within our random error of about 15%. For thicker devices from United Solar, the drift-mobilities were about twice as large when measured using strongly absorbed illumination. We propose that this effect is due to a mobility profile in the intrinsic absorber layer in which the mobility decreases for increasing distance from the substrate.

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