Silicon versus the rest

2014 ◽  
Vol 92 (7/8) ◽  
pp. 553-560 ◽  
Author(s):  
John Robertson
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Amorphous Silicon ◽  
Material Properties ◽  
Thin Film Transistors ◽  
Phase Change Materials ◽  
Optical Storage ◽  
Large Area ◽  
Oxide Semiconductors ◽  
Storage Technology

We review the material properties that allowed amorphous silicon to become the dominant large area semiconductor and then point out how amorphous oxide semiconductors could displace a-Si in thin film transistors, and how phase change materials, such as GeSbTe alloys, have provided an optical storage technology and will provide a nonvolatile electrical storage technology based on their unique properties.

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.

Chalcogenide thin-film transistors using oxygenated n-type and p-type phase change materials

2008 ◽  
Vol 93 (4) ◽  
pp. 043514 ◽  
Author(s):  
Ki-Bong Song ◽  
Sung-Won Sohn ◽  
JunHo Kim ◽  
Kyung-Am Kim ◽  
Kyuman Cho
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Thin Film Transistors ◽  
Phase Change Materials ◽  
Type Phase ◽  
P Type ◽  
Chalcogenide Thin Film

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.

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.

High Performance Input Scanning Arrays Using Amorphous Silicon Photodiodesand Thin-Film Transistors

1992 ◽  
Vol 258 ◽  
Author(s):  
Richard L. Weisfield
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
High Speed ◽  
High Performance ◽  
Test Results ◽  
Large Area ◽  
Full Page ◽  
Hydrogenated Amorphous ◽  
Low Capacitance

ABSTRACTThe use of large area hydrogenated amorphous silicon (a-Si:H) technology has enabled compact, full page width scanners to be built inexpensively, and is now the dominant method for fabricating low-end facsimile machines. This technology has now been extended to scanners with considerably higher levels of performance. High speed, high resolution, full-width input scanning arrays have been developed using a-Si:H photodiodes and thin-film transistors (TFTs). A 12” long array has been designed to scan 3 colors at 400 spots per inch, and operates at speeds of up to 40 pages per minute, achieving a signal/noise ratio of 400:1 at intensities of 30 μWcm-2.The color scan array is made using 3 rows of a-Si:H photodiodes, one per color, addressed by TFTs which share sets of common data lines. The data lines are arranged in a low capacitance non-crossing configuration which allows the scanner to achieve high responsivity with low crosstalk. The data lines are connected to a number of readout chips, each of which amplifies and multiplexes the photosignals onto a single video output line. Optoelectronic test results and images obtained from this device will be presented. These results indicate that high quality color images can be obtained from a-Si:H scanners, and that the present scanner is more limited by the speed of the readout chips than by the a-Si: H devices themselves.

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