Urbach energy dependence of the stability in amorphous silicon thin-film transistors

1999 ◽  
Vol 74 (22) ◽  
pp. 3374-3376 ◽  
Author(s):  
R. B. Wehrspohn ◽  
S. C. Deane ◽  
I. D. French ◽  
I. G. Gale ◽  
M. J. Powell ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Energy Dependence ◽  
Thin Film Transistors ◽  
Urbach Energy ◽  
Silicon Thin Film ◽  
The Stability

Absence of enhanced stability in deuterated amorphous silicon thin film transistors

2004 ◽  
Vol 808 ◽  
Author(s):  
Shufan Lin ◽  
Andrew J. Flewitt ◽  
William I. Milne ◽  
Ralf B. Wehrspohn ◽  
Martin J. Powell
Keyword(s):  
Thin Film ◽  
Growth Rate ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Bond Breaking ◽  
Process Conditions ◽  
Silicon Thin Film ◽  
Ion Energy ◽  
The Stability ◽  
Bottom Gate

ABSTRACTA comparison of the threshold voltage shift after gate-bias stress in hydrogenated and fully deuterated amorphous silicon thin film transistors (TFTs) is presented. A series of fully deuterated bottom gate TFTs consisting of a deuterated n+ contact layer, deuterated intrinsic amorphous silicon (deposited at a range of pressures) and deuterated silicon nitride gate insulator have been produced. A similar series of fully hydrogenated bottom gate TFTs have also been produced, and the stability of the two sets of devices compared. Deuterated and hydrogenated amorphous silicon deposited under the same process conditions do not have the same material properties due to the difference in the ion energy of H and D in the plasma. However, deuterated and hydrogenated material deposited at the same growth rate have almost identical structural properties. Hydrogenated and deuterated TFTs are found to exhibit the same variation in stability as a function of growth rate. In particular, there is no evidence for increased stability in deuterated TFTs. Previous reports of more stable deuterated TFTs, by other groups, can be explained by a change in the Si network properties due to the higher ion energy of deuterium in comparison with hydrogen, when using similar deposition conditions. The implication of our experimental results is that, for the same amorphous network and hydrogen/deuterium concentration, the stability is identical for hydrogenated and deuterated TFTs. Therefore, there is no giant isotopic effect in amorphous silicon TFTs. The study also further supports the idea that Si-Si bond breaking is the rate-limiting step for Si dangling bond defect creation, rather than Si-H bond breaking.

Relative importance of the Si–Si bond and Si–H bond for the stability of amorphous silicon thin film transistors

2000 ◽  
Vol 87 (1) ◽  
pp. 144-154 ◽  
Author(s):  
R. B. Wehrspohn ◽  
S. C. Deane ◽  
I. D. French ◽  
I. Gale ◽  
J. Hewett ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Relative Importance ◽  
Silicon Thin Film ◽  
The Stability

Stability of Amorphous Silicon Thin Film Transistors

1999 ◽  
Vol 557 ◽  
Author(s):  
R.B. Wehrspohn ◽  
S.C. Deane ◽  
I.D. French ◽  
J. Hewett ◽  
M.J. Powell
Keyword(s):  
Thin Film ◽  
Hydrogen Bonding ◽  
Amorphous Silicon ◽  
Hydrogen Content ◽  
Thin Film Transistors ◽  
Energy Barrier ◽  
Urbach Energy ◽  
Intrinsic Stress ◽  
Silicon Thin Film ◽  
Bias Stress

AbstractDangling bond defects are created during positive bias stress of amorphous silicon thin film transistors and there is an energy barrier between 0.9 and 1 eV for this process. We have studied how this energy barrier depends on the material parameters of the amorphous silicon, namely hydrogen content, hydrogen bonding, Urbach energy and intrinsic, deposition induced stress. We observe no dependence on the hydrogen content or hydrogen bonding type, but we do observe a clear dependence on the Urbach energy and the intrinsic stress. These measurements support a localized model for defect creation involving Si-Si bond breaking and the switching of a neighboring H atom to stabilize the broken bond. These results suggest that stable amorphous silicon TFTs can be obtained at low deposition temperatures by control of the deposition-induced, intrinsic stress.

The Instability Characteristics of Amorphous Silicon Thin Film Transistors with Various Interfacial and Bulk Defect States

1997 ◽  
Vol 36 (Part 1, No. 10) ◽  
pp. 6226-6229 ◽  
Author(s):  
Huang-Chung Cheng ◽  
Jun-Wei Tsai ◽  
Chun-Yao Huang ◽  
Fang-Chen Luo ◽  
Hsing-Chien Tuan
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Defect States ◽  
Silicon Thin Film

Hot-Wire Deposited Amorphous Silicon Thin-Film Transistors

1996 ◽  
Vol 424 ◽  
Author(s):  
R. E. I. Schropp ◽  
K. F. Feenstra ◽  
C. H. M. Van Der Werf ◽  
J. Holleman ◽  
H. Meiling
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Chemical Vapor ◽  
Current Crowding ◽  
Hot Wire ◽  
Saturation Regime ◽  
Silicon Thin Film ◽  
Order Of Magnitude

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.

Low frequency noise in amorphous silicon thin film transistors with SiNx gate dielectric

2009 ◽  
Vol 105 (12) ◽  
pp. 124504 ◽  
Author(s):  
S. L. Rumyantsev ◽  
Sung Hun Jin ◽  
M. S. Shur ◽  
Mun-Soo Park
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Silicon Thin Film

Effects of the Deposition Sequence on Amorphous Silicon Thin-Film Transistors

1989 ◽  
Vol 28 (Part 1, No. 11) ◽  
pp. 2197-2200 ◽  
Author(s):  
Kouichi Hiranaka ◽  
Tetsuzo Yoshimura ◽  
Tadahisa Yamaguchi
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Silicon Thin Film
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