High-voltage amorphous silicon thin-film transistors

Martin, Robert J.; Costa, Vander Menengoy da; Hack, M.; Shaw, J. G.

doi:10.1109/16.199371

Cited by 44 publications

(13 citation statements)

References 16 publications

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“…[19] Polysilicon HVTFTs high voltage operation is very sensitive to grain boundaries: the polycrystalline channel selfheats under a high electric field, leading to destructive kink effects at high-voltage. [18,20] Amorphous silicon semiconductor technologies are promising for high voltage operation, [21][22][23] and have been demonstrated up to 800 V, [24] but are limited by low on-currents in the µA range, thus limiting switching speed when they are used to control capacitive loads, such as DEAs.…”

Section: P3mentioning

confidence: 99%

“…We used an offset gate geometry, as this geometry has been shown to increase the maximum operation voltage of TFTs by several hundreds of volts. [18,19,[21][22][23][24] The gate electrode was offset from the drain by 150 µm. With the implementation of these two material and geometrical modifications, the HVTFT breakdown voltage reached 1.1 kV, the highest breakdown voltage reported for a TFT up to date.…”

Section: P3mentioning

confidence: 99%

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Flexible Zinc–Tin Oxide Thin Film Transistors Operating at 1 kV for Integrated Switching of Dielectric Elastomer Actuators Arrays

et al. 2017

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Flexible high-voltage thin-film transistors (HVTFTs) operating at more than 1 kV are integrated with compliant dielectric elastomer actuators (DEA) to create a flexible array of 16 independent actuators. To allow for high-voltage operation, the HVTFT implements a zinc-tin oxide channel, a thick dielectric stack, and an offset gate. At a source-drain bias of 1 kV, the HVTFT has a 20 µA on-current at a gate voltage bias of 30 V. Their electrical characteristics enable the switching of DEAs which require drive voltages of over 1 kV, making control of an array simpler in comparison to the use of external high-voltage switching. These HVTFTs are integrated in a flexible haptic display consisting of a 4 × 4 matrix of DEAs and HVTFTs. Using a single 1.4 kV supply, each DEA is independently switched by its associated HVTFT, requiring only a 30 V gate voltage for full DEA deflection. The 4 × 4 display operates well even when bent to a 5 mm radius of curvature. By enabling DEA switching at low voltages, flexible metal-oxide HVTFTs enable complex flexible systems with dozens to hundreds of independent DEAs for applications in haptics, Braille displays, and soft robotics.

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Section: P3mentioning

confidence: 99%

Section: P3mentioning

confidence: 99%

Flexible Zinc–Tin Oxide Thin Film Transistors Operating at 1 kV for Integrated Switching of Dielectric Elastomer Actuators Arrays

et al. 2017

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“…Applications of high-voltage (>100 V) electronics are growing in numbers in the fields of MEMS, 1 X-ray detectors, 2 solar cells, 3 and soft actuators such as dielectric elastomer actuators (DEAs). 4 Designing high-voltage components that can be integrated with these transducers, such as high-voltage diodes 5 or high-voltage thin film transistors (HVTFTs), [1][2][3][4][6][7][8][9][10] is critical to achieve more complex devices such as arrays, 1,4 displays, 3,4,6 or soft robots. 11,12 Integrated high-voltage electronics can replace the more traditional bulky optocouplers and power MOSFETs, which limit the compactness of arrays made of high voltage transducers.…”

mentioning

confidence: 99%

“…4,9 HVTFTs require a different architecture compared to their lower voltage counterparts, which are designed for optimal operation below 10 V. The HVTFTs can operate at high voltage with a gate electrode offset from the drain, also called offset gate, 1,3,4,6-10 a thicker gate dielectric with high breakdown strength 4,13 and field plates. 7,9,10 These modifications to the transistor gate increase the device breakdown voltage by 1 to 2 orders of magnitude. 1,4,9 However, those modifications strongly decrease the HVTFT transistor performance: the on-off ratio of a HVTFTs is usually lower than 10 4 and the subthreshold swing value can be higher than 10 V/dec.…”

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confidence: 99%

Yttrium zinc tin oxide high voltage thin film transistors

Marette

Shea

Briand

2018

Applied Physics Letters

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We demonstrate that doping the semiconductor zinc tin oxide (ZTO) with yttrium leads to a highvoltage thin film transistor (HVTFT) with enhanced switching performance. Adding 5% yttrium leads to an increase in the on-off ratio from 40 to 1000 at an operating voltage of 500 V and to a drop of the subthreshold swing from 65 to 35 V/dec. The performance is improved because of the reduction of the saturation voltage and because of a decrease in the off-current from several lA for undoped ZTO HVTFTs to 100 nA for Y 5% ZTO. The decrease in saturation voltage and off-current can be attributed to a lower trap concentration leading to enhanced space-charge limited current and to a decrease in the background charge carrier concentration. At a 500 V bias voltage, an inverter circuit with a yttrium-doped ZTO HVTFT can control the output voltage between 50 V and 500 V, while the undoped ZTO HVTFT can only control the output voltage between 150 V and 450 V. The improvement in high voltage performance of yttrium-doped ZTO HVTFTs is important for future work related to high voltage thin film transistors made of amorphous oxide semiconductors as it demonstrates that this technology enables HVTFTs with simultaneously high operation voltage, high on-current, and high on-off ratio.

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“…8 Within the OD structure the high field regions are again located at the edges of the offset region and arise from the depletion formed between the sharp corner of the gate ͑which is held at low potential͒ and the high drain potential. 13 The high field regions in OD and MFP structures typically result in oxide failure. This is supported by our observation of a sharp, unrecoverable breakdown.…”

mentioning

confidence: 99%