scholarly journals Localised States in Microcrystalline Silicon Photovoltaic Structures Studied by Post-Transit Time-of-Flight Spectroscopy

2003 ◽  
Vol 762 ◽  
Author(s):  
Steve Reynolds ◽  
Vladimir Smirnov ◽  
Charlie Main ◽  
Reinhard Carius ◽  
Friedhelm Finger
Keyword(s):  
Transit Time ◽  
Carrier Transport ◽  
Time Of Flight ◽  
Microcrystalline Silicon ◽  
Mobility Edge ◽  
Cell Structures ◽  
Multiple Trapping ◽  
Multiple Trapping Model ◽  
Localised States ◽  
Time Of Flight Spectroscopy

AbstractPost-transit time-of-flight spectroscopy has been used to study the density of states distribution in hot-wire CVD microcrystalline silicon pin solar cell structures. For an absorber layer Raman scattering intensity ratio ICRS of 0.4 or less, behaviour consistent with multiple-trapping carrier transport is observed and may be interpreted in terms of a conduction-band tail of some 18 meV slope plus a broad defect bump of order 1017 cm-3 centered at 0.55 eV relative to the mobility edge. As ICRS is increased beyond 0.4, the temperature-dependence of the photocurrent transient becomes inconsistent with multiple-trapping and above 0.6 the decays are almost temperature-independent. By comparing data taken at 300 K, it may be inferred from the multiple-trapping model that localised states between 0.35 and 0.5 eV are associated with the presence of columns or clusters of nanocrystals and those deeper than 0.5 eV with the amorphous tissue. Results are compared with previous work on coplanar and sandwich structures.

scholarly journals Solutions of q-deformed multiple-trapping model (MTM) for charge carrier transport from time-of-flight transient (TOF) photo-current in amorphous semiconductors

2020 ◽  
Vol 66 (5 Sept-Oct) ◽  
pp. 643
Author(s):  
F. Serdouk ◽  
A. Boumali ◽  
A. Makhlouf ◽  
M.L. Benkhedi
Keyword(s):  
Charge Carrier ◽  
Carrier Transport ◽  
Time Of Flight ◽  
Amorphous Semiconductors ◽  
Charge Carrier Transport ◽  
Multiple Trapping ◽  
Multiple Trapping Model ◽  
Trapping Model ◽  
A Current ◽  
Photo Current

This paper is devoted to investigating the description of the q-deformed multiple-trapping equation for charge carrier transport in amorphous semiconductors. For this, we at first modified the multi–trapping model (MTM) of charge carriers in amorphous semiconductors from time-of-flight (TOF) transient photo-current in the framework of the q-derivative formalism, and then, we have constructed, our simulated current by using a method based on the Laplace method. This method is implemented in a program proposed recently by [14] which allows us to construct a current using the Padé approximation expansion.

The Increased Response Time in Hydrogenated Microcrystalline Silicon - A Fermi Level Effect or a Structural Effect in a Grainy Material?

1996 ◽  
Vol 420 ◽  
Author(s):  
S. Grebner ◽  
P. Popovic ◽  
J. Furlan ◽  
Q. Gu ◽  
R. Schwarz
Keyword(s):  
Fermi Level ◽  
Structural Effect ◽  
Level Shift ◽  
Microcrystalline Silicon ◽  
One Dimensional ◽  
Fermi Level Shift ◽  
Multiple Trapping ◽  
Multiple Trapping Model ◽  
Simulation Based ◽  
Level Effect

AbstractThe typical photocurrent decay time τR in intrinsic prepared hydrogenated microcrystalline silicon (μc-Si:H) is around lms similar to its n-doped amorphous counterpart (a-Si:H:P). Depending on the crystalline fraction Xc, the μc-Si:H films show an activation energy near to or below 0.5eV. To find out if this analogy ofτR could be due to a Fermi level shift or to the grainy structure in gc-Si:H films, we have studied the behaviour of τR in doped a-Si:H and gc-Si:H films of different XC. One-dimensional numerical simulation based on the Multiple Trapping Model (MTM) can explain this increase in terms of a Fermi level shift towards the conduction band. On the other hand, detailed measurements for temperatures from 100 to 400 K point to carrier trapping in deep states, most probably located at grain boundaries.

Hopping of Electrons in Hybrid Band Tails of a-Si1-xGex:H

1990 ◽  
Vol 192 ◽  
Author(s):  
C. E. Nebel ◽  
H. C. Weller ◽  
G.H. Bauer
Keyword(s):  
Conduction Band ◽  
Alloy Composition ◽  
Time Of Flight ◽  
State Density ◽  
Mobility Edge ◽  
Medium Temperature ◽  
Tail State ◽  
Current Decay ◽  
Thermally Activated ◽  
Multiple Trapping

ABSTRACTThe thermalization of electrons in the medium temperature range (120K ≤ T ≤ 200K) is investigated by time-of-flight experiments on a-SiGe:H mim structures. The evaluation of the pre-transit current decay reveals a dual slope characteristic which reflects an initial hopping down (I ∼ t−1) followed by a thermally activated (I ∼ t−p 0 < p < 1) process. The transition time from hopping down to multiple trapping sensitively depends on temperature and alloy composition. The experimentally deduced features can be explained by the increased tail state density at the conduction band mobility edge of a-SiGe:H samples compared to a-Si:H.

Multiple-Trapping Model with Meyer-Neldel Effect and Field-Dependent Effects: Time-Of-Flight Simulations for a-Si:H

2005 ◽  
Vol 862 ◽  
Author(s):  
Jesse Maassen ◽  
Arthur Yelon ◽  
Louis-André Hamel ◽  
Wen Chao Chen
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Carrier Transport ◽  
Localized States ◽  
Combined Model ◽  
Multiple Trapping ◽  
Multiple Trapping Model ◽  
Field Dependent ◽  
Trapping Model ◽  
Flight Simulations

AbstractWe have included both the Meyer-Neldel rule and field assisted detrapping in the multiple-trapping model, assuming exponential band tails of localized states. Monte Carlo simulations with fixed parameters provide transient currents and comparison of calculated and measured mobility, μ(T,F), and pre-transit dispersion parameter, α1(T,F), which are presented for temperatures ranging from 25 K to 333 K and fields from 20 kV/cm to 400 kV/cm. We observe that the values of μ1(T,F) and α(T,F) are improved with this combined model. Although this model provides satisfactory results for carrier transport for all temperature and field, differences in experimental data causes deviation of simulated results from experiment.

Time-resolved Photoconductivity as a Probe of Carrier Transport in Microcrystalline Silicon

2006 ◽  
Vol 910 ◽  
Author(s):  
Steve Reynolds
Keyword(s):  
Density Of States ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Film Growth ◽  
Hole Mobility ◽  
Transport Parameters ◽  
Microcrystalline Silicon ◽  
Time Resolved ◽  
Transient Photoconductivity ◽  
Transport Measurements

AbstractThe use of transient photoconductivity techniques in the investigation of carrier transport in microcrystalline silicon is described. Results are presented which highlight variations in transport parameters such as carrier mobility and density of states with structure composition. Hole mobility is significantly enhanced by crystalline content in the film of 10% or less. The density of states inferred from transport measurements parallel to and at right angles to the direction of film growth differ somewhat, suggesting that transport may be anisotropic.

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