Source-gated thin-film transistors

Shannon, John M.; Gerstner, Ed

doi:10.1109/led.2003.813379

Cited by 100 publications

(137 citation statements)

References 8 publications

Supporting

Mentioning

132

Contrasting

Order By: Relevance

“…In general, the SGT has a higher output impedance and a lower saturation voltage than a geometrically identical thin-film FET (TFT) [1][2][3]. It therefore should perform well in analog circuits where high amplification and low power consumption is a prerequisite.…”

Section: Introductionmentioning

confidence: 99%

Low-Field Behavior of Source-Gated Transistors

Shannon

Sporea

Georgakopoulos

et al. 2013

IEEE Trans. Electron Devices

View full text Add to dashboard Cite

-A physical description for low-field behavior of a Schottky source-gated transistor (SGT) is outlined where carriers crossing the source barrier by thermionic emission are restricted by JFET action in the pinch-off region at the drain end of the source. This mode of operation leads to transistor characteristics with low saturation voltage and high output impedance without the need for field relief at the edge of the Schottky source barrier and explains many characteristics of the SGT observed experimentally. Two-dimensional device simulations with and without barrier lowering due to the Schottky effect show that transistors can be designed so that the current is independent of source length and thickness variations in the semiconductor. This feature, together with the fact that the current in an SGT is independent of source-drain separation, hypothesizes the fabrication of uniform current sources and other large-area analog circuit blocks with repeatable performance even in imprecise technologies such as high-speed printing.

show abstract

Section: Introductionmentioning

confidence: 99%

Low-Field Behavior of Source-Gated Transistors

Shannon

Sporea

Georgakopoulos

et al. 2013

IEEE Trans. Electron Devices

View full text Add to dashboard Cite

show abstract

“…Most of the SGT current flows at the periphery of the source barrier opposite to the drain [8]. Details of the operation of the SGT have been described previously [6][7][8][9].…”

Section: Operation Of Source-gated Transistormentioning

confidence: 99%

High Performance Transistors in Low Mobility Organic Semiconductors for Analog and High-Frequency Applications

Guo

Balon

Hatton

et al. 2008

2008 Flexible Electronics and Displays Conference and Exhibition

View full text Add to dashboard Cite

In conventional organic field-effect transistors (OFETs), the low mobility of carriers in the organic semiconductor layers leads to low device speed, which seriously limits the applicability of the devices for analog and high frequency circuits in high performance applications. In this paper, the sourcegated transistor (SGT) concept is introduced for high performance transistors in low mobility organic semiconductors, in which the source comprises a potential barrier to current flow and a gate is used to modulate the electric field at the reverse-biased source barrier and change the current. Compared to the OFET, the OSGT has a much smaller susceptibility to short-channel effects, and can be operated with much higher internal electrical fields giving high drive current and high speed. The numerical simulation results show that the OSGT can be an excellent candidate for designing high performance transistors in low-mobility organic materials for analog and high frequency applications.

show abstract

“…The SGT also has a large output impedance. 5,6 The main difference with a FET is the provision of a source barrier rather than an ohmic contact and a gate located below it that controls the current flowing across the reverse biased barrier. Current saturation occurs when the source barrier depletes the underlying a-Si: H. Ion implantation is used to control the source barrier height and compensate for the region between the source and drain contacts.…”

Section: (Received 23 February 2004; Accepted 19 May 2004)mentioning

confidence: 99%

Stable transistors in hydrogenated amorphous silicon

Shannon¹

2004

Applied Physics Letters

View full text Add to dashboard Cite

Thin-film field-effect transistors in hydrogenated amorphous silicon are notoriously unstable due to the formation of silicon dangling bond trapping states in the accumulated channel region during operation. Here, we show that by using a source-gated transistor a major improvement in stability is obtained. This occurs because the electron quasi-Fermi level is pinned near the center of the band in the active source region of the device and strong accumulation of electrons is prevented. Thin-film field-effect transistors (FETs) made using hydrogenated amorphous silicon ͑a-Si: H͒ as the semiconductor are notoriously unstable. This instability, characterized by a large shift in threshold voltage and a reduction in drain current during operation, 1 severely limits their use in both analog and digital circuits for displays and large area electronics, in general. As such, the most important application is as a simple pixel switch in actively addressed liquid-crystal display arrays with anything more demanding such as peripheral or pixel circuitry being difficult or impossible.Silicon dangling bond defects are formed over a wide range of energies within the band gap of amorphous silicon in regions where the electron quasi-Fermi level moves from its equilibrium position determined during the growth of the a-Si: H.1,2 This position, close to the center of the band in undoped material, determines the energy distribution and number of the different bonding configurations between silicon and hydrogen when in chemical equilibrium. For a FET, the electron quasi-Fermi level in the channel region moves toward the conduction band as the transistor is biased into accumulation. 3,4 This is accompanied by an increase in the electron concentration. The microscopic mechanisms for the creation of dangling bond defect states are complex 3 as the material strives to achieve an equilibrium between the weak silicon-silicon bonds, the dangling bond defects and the electron concentration.4 Defect states trap electrons and there is a shift in the threshold voltage of the FET.Since the defect generation mechanism is fundamental, there is very little that can be done about it in FETs as they rely on electron accumulation in a channel region for their operation. At a given gate voltage, drift and instability are independent of current and are particularly severe when operating well above threshold.Source-gated transistors (SGTs) 5 form a class of thinfilm transistors in which the current is controlled entirely by the source. 6 Their most important advantage compared with a FET is the much smaller saturation voltage V SAT . An example of the characteristics of a SGT made using a Schottky barrier source is shown in Fig. 1 together with a schematic showing its structure. V SAT at V G =20 is Ͻ2.5 V. This compares with 17 V ͑V G − V T ͒ for a FET made with the same layers. The SGT also has a large output impedance. 5,6 The main difference with a FET is the provision of a source barrier rather than an ohmic contact and a gate located below it that con...

show abstract

Source-gated thin-film transistors

Cited by 100 publications

References 8 publications

Low-Field Behavior of Source-Gated Transistors

Low-Field Behavior of Source-Gated Transistors

High Performance Transistors in Low Mobility Organic Semiconductors for Analog and High-Frequency Applications

Stable transistors in hydrogenated amorphous silicon

Contact Info

Product

Resources

About