Comments on Electron and Hole Transport in the Band Tail States of Amorphous Silicon at Low Temperatures

1989 ◽  
Vol 149 ◽  
Author(s):  
M. Silver ◽  
W. E. Spear
Keyword(s):  
Amorphous Silicon ◽  
Drift Mobility ◽  
Hole Transport ◽  
Experimental Results ◽  
Exponential Tail ◽  
Band Tail ◽  
State Distribution ◽  
Temperature Drift ◽  
Model Calculations ◽  
Tail State

ABSTRACTRecent experimental results on the low temperature drift mobility in amorphous silicon are examined on the basis of the approach to hopping transport developed by Silver and Bässler. It is shown on general grounds that the main features of the experimental results cannot be explained by a purely exponential tail state distribution, but are consistent with the distribution used by Spear and Cloude (1988) in model calculations.

Defect Structure and Network Disorder in Boron Doped Amorphous Silicon

1991 ◽  
Vol 219 ◽  
Author(s):  
M. B. Schubert ◽  
G. Schumm ◽  
E. Lotter ◽  
K. Eberhardt ◽  
G. H. Bauer
Keyword(s):  
Hydrogen Bonding ◽  
Fermi Level ◽  
Amorphous Silicon ◽  
Defect Structure ◽  
Boron Concentration ◽  
Hole Transport ◽  
Local Defect ◽  
Band Tail ◽  
Boron Doped ◽  
Transport Path

ABSTRACTA series of boron doped a-Si:H films have been characterized by PDS, FTIR, Raman, and SIMS in order to evaluate the effects of boron incorporation on structural properties and hydrogen bonding. Doping by B2H6 or B(CH3)3 does not significantly enhance the overall disorder of the silicon network showing up in the TO-like Raman halfwidth whereas remarkable changes in local, defect related structures are evident from PDS. An analysis of the data suggests two bands of defects in the pseudogap at low boron concentration and only one band for higher concentration. To account for Fermi level positions, shifts of the hole transport path well into the valence band tail upon doping must be invoked.

Application of Exponential Tail-State Distribution Model to the Above-Threshold Characteristics of Zn-Based Oxide Thin-Film Transistors

2009 ◽  
Vol 56 (9) ◽  
pp. 2165-2168 ◽  
Author(s):  
Kazushige Takechi ◽  
Mitsuru Nakata ◽  
Toshimasa Eguchi ◽  
Hirotaka Yamaguchi ◽  
Setsuo Kaneko
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Oxide Thin Film ◽  
Distribution Model ◽  
Exponential Tail ◽  
State Distribution ◽  
Tail State

Time-of-Flight Measurements in a-Si:H Between Room Temperature and 130° C°

1987 ◽  
Vol 95 ◽  
Author(s):  
D. S. Shen ◽  
S. Aljishi ◽  
Z E. Smith ◽  
J. P. Conde ◽  
V. Chu ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Room Temperature ◽  
Time Of Flight ◽  
High Sensitivity ◽  
Drift Mobility ◽  
Hole Transport ◽  
Dispersive Transport ◽  
Band Tail ◽  
Flight Measurements

AbstractThe drift mobility μd and the mobility-lifetime product μτ in undoped a-Si:H have been studied up to 130°C. The electron μde is temperature-activated with Eae = 0.13 to 0.16 eV. The electron (μτ)e increases with temperature T. For hole transport, we observe the transition from dispersive to non-dispersive transport with increasing T. The hole μdh is ∼ 1/100 of μde, and is activated with Eah = 0.34 to 0.48eV. The hole (μτ)h does not change much with T. A computer simulation demonstrates the high sensitivity of μd to the band tail width.

Transport Measurements in LPCVD Amorphous Silicon Obtained from Disilane.

1986 ◽  
Vol 70 ◽  
Author(s):  
C. Manfredotti ◽  
G. Gervino ◽  
L. Montaldi ◽  
U. Nastasi ◽  
R. Murri ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Amorphous Silicon ◽  
Energy Shift ◽  
State Distribution ◽  
Mobility Edge ◽  
Temperature Conductivity ◽  
Exponential Factor ◽  
Tail State ◽  
A Value

ABSTRACTMeasurements of high temperature conductivity on a-Si:H obtained by LPCVD from Si2H6 at temperatures between 450 and 500 °C indicate clearly a change on the activation energy from 0.9 - 1.0 eV to 0.55 - 0.6 eV around 600 °K.The results are not strongly different from those obtained in GD a- SiH4:however, the coefficent of the energy shift of the mobility edge with temperature is greater by a factor of 2, while the average extension of the tail state distribution at T= 0 °K is roughly a factor 1.5 larger. The main discrepancy concerns the pre-exponential factor, which is one or two orders of magnitude larger, giving a product (NcukT)of the order of 1021 cm-1 s-1. By assuming a conduction mobility two orders of magnitude larger than the maesured Hall mobility one obtains a value for N which is only a factor four times larger than what currently assumed for a-Si:H.

Electron and Hole Transport in a-SiH at High Field and Low Temperature

1992 ◽  
Vol 258 ◽  
Author(s):  
C. E. Nebel ◽  
R. A. Street
Keyword(s):  
Electron Transport ◽  
Low Temperature ◽  
Field Effect ◽  
High Field ◽  
Hole Transport ◽  
Space Charge Limited Current ◽  
Band Tail ◽  
Tail State ◽  
Current Decay ◽  
Enhanced Conductivity

ABSTRACTLow temperature, high field properties of electron and hole transport are investigated by time-of-flight (TOF), steady-state and transient space charge limited current (SCLC) experiments on intrinsic a-Si:H. Charge collection and TOF experiments performed at T= 80 K reveal hole μτ-products of = 8 × 10-10 cm2/V and hole mobilities μ ≤ 9×10-3 cm2/Vs. The field effect on hole thermalization is demonstrated by evaluation of the post transit current decay. SCLC experiments on p+ -i-n+ (electron transport) and p + -i-n+ (hole transport) configurations are introduced and interpreted in terms of field enhanced conductivity and mobility. The experiments demonstrate the overwhelming field effect on carrier hopping in the band tail regions of a-Si:H. Considerably higher fields have to be applied in the case of hole transport than electron transport to achieve comparable conductivities; this is discussed on the basis of the different tail state distributions and localization lengths.

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