Effects of Mechanical Strain on Amorphous Silicon Thin-Film Transistors

2002 ◽  
Vol 715 ◽  
Author(s):  
H. Gleskova ◽  
S. Wagner ◽  
W. Soboyejo ◽  
Z. Suo
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Leakage Current ◽  
Thin Film Transistors ◽  
Tensile Strain ◽  
Mechanical Strain ◽  
Positive Sign ◽  
Silicon Thin Film ◽  
Polyimide Foil

AbstractWe evaluated a-Si:H TFTs fabricated on polyimide foil under uniaxial compressive or tensile strain. The strain was induced by bending or stretching. All experiments confirmed that the on-current and hence the electron linear mobility depend on strain å as μ = μ0 (1 + 26·ε), where tensile strain has a positive sign. Upon the application of stress the mobility changes instantly and then remains unchanged in measurements up to 40 hours. In the majority of the TFTs the off-current and leakage current do not change. In tension, the TFTs fail mechanically at a strain of ∼ 3x10-2 but recover if the strain is released ‘immediately’.

Characterization of Photo Leakage Current of Amorphous Silicon Thin-Film Transistors

1999 ◽  
Vol 38 (Part 1, No. 11) ◽  
pp. 6202-6206 ◽  
Author(s):  
Yoshimi Yamaji ◽  
Mitsushi Ikeda ◽  
Masahiko Akiyama ◽  
Takahiko Endo
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Leakage Current ◽  
Thin Film Transistors ◽  
Silicon Thin Film

Studies of the Stability of Amorphous Silicon Thin Film Transistors

1992 ◽  
Vol 258 ◽  
Author(s):  
T. Globus ◽  
M. Shur ◽  
M. Hack
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Leakage Current ◽  
Thin Film Transistors ◽  
Experimental Studies ◽  
Gate Insulator ◽  
Localized States ◽  
Silicon Thin Film ◽  
Insulator Layer ◽  
Voltage Stress

ABSTRACTOur experimental studies confirm that changes in a-Si Thin Film Transistors (TFTs) under voltage stress occur in the device channel and not in the contacts. We demonstrate that stressing an a-Si TFT not only shifts the device threshold voltage but can also changes the slope of the semilog subthreshold current dependence on the gate voltage. In addition, stressing can decrease the minimum leakage current. The creation of new localized states in the amorphous silicon under voltage stress qualitatively explains all these effects, while carrier tunneling and trapping in the gate insulator layer cannot by itself explain our data. At large negative gate voltages, the leakage current increases due to the holes injected into the channel. This hole current is also affected by voltage stress as can be predicted by the state creation mechanism.

Effects of Mechanical Strain on the Electrical Performance of Amorphous Silicon Thin-Film Transistors with a New Gate Dielectric

2009 ◽  
Vol 1196 ◽  
Author(s):  
Katherine Wei Song ◽  
Lin Han ◽  
Sigurd Wagner ◽  
Prashant Mandlik
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Hybrid Material ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Compressive Strain ◽  
Mechanical Strain ◽  
Electrical Performance ◽  
Silicon Thin Film ◽  
Transfer Characteristics

AbstractThe stiff SiNx gate dielectric in conventional amorphous silicon thin film transistors (TFTs) limits their flexibility by brittle fracture when in tension. We report the effect on the overall flexibility of TFTs of replacing the brittle SiNx gate dielectric with a new, resilient SiO2-silicone hybrid material, which is deposited by plasma enhanced chemical vapor deposition. Individual TFTs on a 50μm-thick polyimide foil were bent to known radii, and measurement of transfer characteristics were made both during strain and after re-flattening. Compared with conventional TFTs made with SiNx, TFTs made with the new hybrid material demonstrated similar flexibility when strained in compression and significantly increased flexibility when strained in tension. Under bending to compressive strain, all TFTs tested delaminated from the substrate for compressive strains greater than 2%. Conventional a-Si:H/SiNx TFTs have been previously found to delaminate at a similar compressive strain. Under bending to tensile strain, the most flexible TFTs made with the new hybrid material that were tested after re-flattening did not exhibit significant changes in transfer characteristics up to strains of ∼2.5%. Conventional a-Si:H/SiNx TFTs have been found to remain functional for strains of up to 0.5%, a value only one-fifth of that for TFTs made with the new hybrid material.

Stability of Amorphous Silicon Thin Film Transistors under Prolonged High Compressive Strain

2007 ◽  
Vol 989 ◽  
Author(s):  
Jian-Zhang Chen ◽  
I-Chun Cheng ◽  
Sigurd Wagner ◽  
Warren Jackson ◽  
Craig Perlov ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Compressive Strain ◽  
Mechanical Strain ◽  
Channel Length ◽  
Silicon Thin Film ◽  
Roll To Roll ◽  
Hydrogenated Amorphous ◽  
Current Drop

AbstractWe studied the effect of prolonged mechanical strain on the electrical characteristics of thin-film transistors of hydrogenated amorphous silicon made at a process temperature of 150°C on 51-μm thick Kapton polyimide foil substrates. Effects are observed only at very high compressive strain of 1.8%. Tensile strain up to fracture at 0.3% to 0.5% does not show any effect, nor does compressive strain substantially less than 1.8%. The TFTs were stressed for times up to 23 days by bending around a tube with axis perpendicular to the channel length, and were evaluated in the flattened state. The changes observed are small. The threshold voltage is increased, the “on” current and the field effect mobility remain essentially constant, and the subthreshold slope, “off” current and gate leakage current drop somewhat. Overall, the observed changes are small. We conclude that mechanical strain caused by roll-to-roll processing and permanent shaping will have negligible effects on TFT performance.

Suppression of Schottky leakage current in island-in amorphous silicon thin film transistors with the Cu∕CuMg as source/drain metal

2007 ◽  
Vol 91 (6) ◽  
pp. 062103 ◽  
Author(s):  
M. C. Wang ◽  
T. C. Chang ◽  
Po-Tsun Liu ◽  
R. W. Xiao ◽  
L. F. Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Leakage Current ◽  
Thin Film Transistors ◽  
Silicon Thin Film
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