Stability of Amorphous Silicon Thin Film Transistors for Analog Circuit Applications

1997 ◽  
Vol 467 ◽  
Author(s):  
R. I. Hornsey ◽  
T. Mahnke ◽  
P. Madeira ◽  
K. Aflatooni ◽  
A. Nathan
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Threshold Voltage ◽  
Analog Circuits ◽  
Thin Film Transistors ◽  
Reverse Bias ◽  
Analog Circuit ◽  
Large Area ◽  
Silicon Thin Film ◽  
Threshold Voltages

ABSTRACTAnalog circuits using amorphous silicon thin film transistors offer significant advantages for in situ signal processing in large-area optical and x-ray imagers. However such circuits are susceptible to gate-bias-induced shifts in the threshold voltages of the constituent transistors. In this work, the change of threshold voltage for devices undergoing cycles of stress, relaxation and reverse bias is measured in order to determine the feasibility of resetting the threshold voltage electrically. It is concluded that, although the reverse bias does assist the recovery of the threshold voltage, the process is still not sufficiently rapid. An analog amplifier circuit is then described which uses negative feedback to achieve a gain that is stable to within 6% over a period of 8 hours.

Threshold Voltage Shifts in Amorphous Silicon Thin Film Transistors under Bias Stress

1990 ◽  
Vol 192 ◽  
Author(s):  
Tetsu Ogawa ◽  
Sadayoshi Hotta ◽  
Horoyoshi Takezawa
Keyword(s):  
Thin Film ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Charge Trapping ◽  
The Other ◽  
Time Dependent ◽  
Silicon Thin Film ◽  
Bias Stress

ABSTRACTThrough the time and temperature dependence measurements on threshold voltage shifts (Δ VT) in amorphous silicon thin film transistors, it has been found that two separate instability mechanisms exist; within short stress time ranges Δ Vτ increases as log t and this behavior corresponds to charge trapping in SiN. On the other hand, in long stress time ranges Δ VT increases as t t/4 and can be explained by time-dependent creation of trap in a-Si.

Threshold Voltage Shift of Amorphous Silicon Thin-Film Transistors During Pulse Operation

1991 ◽  
Vol 30 (Part 1, No. 12B) ◽  
pp. 3719-3723 ◽  
Author(s):  
Ryoji Oritsuki ◽  
Toshikazu Horii ◽  
Akira Sasano ◽  
Ken Tsutsui ◽  
Toshiko Koizumi ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Silicon Thin Film ◽  
Pulse Operation ◽  
Threshold Voltage Shift ◽  
Voltage Shift

Material Properties Controlling the Performance of Amorphous Silicon Thin Film Transistors

1984 ◽  
Vol 33 ◽  
Author(s):  
M. J. Powell
Keyword(s):  
Thin Film ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Threshold Voltage ◽  
Material Properties ◽  
Thin Film Transistors ◽  
Gate Insulator ◽  
Dangling Bond ◽  
Silicon Thin Film

ABSTRACTAmorphous silicon thin film transistors have been fabricated with a number of different structures and materials. To date, the best performance is obtained with amorphous silicon - silicon nitride thin film transistors in the inverted staggered electrode structure, where the gate insulator and semiconductor are deposited sequentially by plasma enhanced chemical vapour deposition in the same growth apparatus.Localised electron states in the amorphous silicon are crucial in determining transistor performance. Conduction band states (Si-Si antibonding σ*) are broadened and localised in the amorphous network, and their energy distribution determines the field effect mobility. The silicon dangling bond defect is the most important deep localised state and their density determines the prethreshold current and hence the threshold voltage. The density of states is influenced by the gate insulator interface and there is probably a decreasing density of states away from this interface. The silicon dangling bond defect in the bulk amorphous silicon nitride also leads to a localised gap state, which is responsible for the observed threshold voltage instability.Other key material properties include the fixed charge densities associated with primary passivating layers placed on top of the amorphous silicon. The low value of the bulk density of states in the amorphous silicon layer increases the sensitivity of device characteristics to charge at the top interface.

Reducing threshold voltage shifts in amorphous silicon thin film transistors by hydrogenating the gate nitride prior to amorphous silicon deposition

1997 ◽  
Vol 71 (9) ◽  
pp. 1237-1239 ◽  
Author(s):  
Jun-Wei Tsai ◽  
Chun-Yao Huang ◽  
Ya-Hsiang Tai ◽  
Huang-Chung Cheng ◽  
Feng-Cheng Su ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Silicon Thin Film ◽  
Silicon Deposition

Threshold voltage instability of amorphous silicon thin-film transistors under constant current stress

2005 ◽  
Vol 87 (2) ◽  
pp. 023502 ◽  
Author(s):  
Shah M. Jahinuzzaman ◽  
Afrin Sultana ◽  
Kapil Sakariya ◽  
Peyman Servati ◽  
Arokia Nathan
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Constant Current ◽  
Silicon Thin Film ◽  
Current Stress ◽  
Voltage Instability

Proximity Recovery Layers to Speed up the Recovery of Stressed Amorphous Silicon Thin-Film Transistors

1990 ◽  
Vol 192 ◽  
Author(s):  
M. Hack ◽  
W. B. Jackson ◽  
R. Lujan
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
High Voltage ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Thin Film ◽  
Threshold Voltage Shift ◽  
Speed Up ◽  
Hydrogenated Amorphous

ABSTRACTWe have developed a means to speed up the recovery of both the threshold voltage shift of hydrogenated amorphous silicon (a-Si:H) transistors and the Vx shift of high voltage a-Si devices. This is accomplished by placing a lightly doped compensated layer adjacent to the active layer in these transistors. This proximity recovery layer does not alter the initial characteristics of a-Si:H transistors and is completely process compatible with standard fabrication procedures.

Amorphous Silicon Thin Film Transistors on Kapton Fibers

2002 ◽  
Vol 736 ◽  
Author(s):  
Eitan Bonderover ◽  
Sigurd Wagner ◽  
Zhigang Suo
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Plasma Etching ◽  
Thin Film Transistors ◽  
Textile Industry ◽  
Chemical Vapor ◽  
Electrical Characteristics ◽  
Large Area ◽  
Silicon Thin Film ◽  
Gold Contact

ABSTRACTThe textile industry uses weaving to create very large quantities of fabric very quickly. The goal of our research is to use this well established technology to create complex large-area circuits quickly and efficiently. In our laboratory we have previously shown that amorphous silicon (a-Si) can be used to make thin-Film transistors (TFTs) on Kapton (a highly temperature-resistant polyimide from DuPont). We also previously showed that these TFTs can survive mechanical loads. A process has been designed to make “TFT fibers” by fabricating a-Si TFTs on Kapton. A special TFT geometry has also been developed. The structure consists of 3 large gold contact pads – one for each terminal of the TFT – running along the fiber. These contact pads allow connections to be made between TFT fibers using conductor fibers – Kapton fibers coated only with gold. The TFT fabrication process is based on a low temperature (150°C) Plasma Enhanced Chemical Vapor Deposition (PECVD) process. The TFTs are fabricated on a Kapton sheet from which flat fibers are made by the slit film technique. So far the best method for cutting a Kapton sheet into fibers has been plasma etching. We will describe the electronic characteristics of these TFTs as well as the electrical characteristics of the contacts between TFT fibers.

Sign in / Sign up

Export Citation Format

Share Document