High‐Frequency Operation of Vertical Organic Field‐Effect Transistors

Abstract

The high-frequency and low-voltage operation of organic thin-film transistors (OTFTs) is a key requirement for the commercial success of flexible electronics. Significant progress has been achieved in this regard by several research groups highlighting the potential of OTFTs to operate at several tens or even above 100 MHz. However, technology maturity, including scalability, integrability, and device reliability, is another crucial point for the semiconductor industry to bring OTFT-based flexible electronics into mass production. These requirements are often not met by high-frequency OTFTs reported in the literature as unconventional processes, such as shadow-mask patterning or alignment with unrealistic tolerances for production, are used. Here, ultra-short channel vertical organic field-effect transistors (VOFETs) with a unity current gain cut-off frequency (f T ) up to 43.2 MHz (or 4.4 MHz V −1 ) operating below 10 V are shown. Using state-of-the-art manufacturing techniques such as photolithography with reliable fabrication procedures, the integration of such devices down to the size of only 12 × 6 μm2 is shown, which is important for the adaption of this technology in high-density circuits (e.g., display driving). The intrinsic channel transconductance is analyzed and demonstrates that the frequencies up to 430 MHz can be reached if the parasitic electrode overlap is minimized.

Wafer-scale organic-on-III-V monolithic heterogeneous integration for active-matrix micro-LED displays

“…There have been significant efforts on improving the operation frequency of OTFTs by making ultra-scaled channels, reducing the gate to source/drain overlaps and adopting inorganic high- k gate dielectric layers 48 – 50 . To drive micro-LED displays, achieving large driving current in a limited pixel area is more important.…”

Potential Application of Organic Electronics in Electrical Sensing of Insects and Integrated Pest Management towards Developing Ecofriendly Replacements for Chemical Insecticides

“…In addition, the carbon-based nature of organic materials, and the absence of heavy metals in these devices make this technology quite environmentally friendly. In previous works, we have achieved solution-sheared printed organic semiconductor layers with reliable charge carrier mobilities up to 12 cm 2 V −1 s −1 , [28] fullyprinted semi-transparent all-polymer organic field effect transistors (OFETs) working up to 48 V, [29] an audio system consisting of an OFET amplifier and a 128 cm 2 piezo-polymer loudspeaker on plastic substrate reproducing sound pressure levels up to 60 dBA, [30] and thermally-evaporated vertical organic transistors with a device area as small as ≈20 μm × 20 μm and small-signal current-gain cutoff frequency up to f T = 43.2 MHz at 9.8 V. [31] f T up to 160 MHz has been demonstrated by other groups at 40 V. [32] An intelligent electronic trap that works as an alternative to chemical insecticides shall be able to do the following basic functions: a) attract the insects, b) detect an insect sitting on the trap, c) identify the insect, i.e., guess with a low error rate the insect family to distinguish between the pests and nontarget insects, and d) destroy the pest while not attacking the other in-sects. In addition, this trap should be low-cost, not cause pollution to the environment or the produced crops, and be electrically safe if it is accidentally touched by humans or animals such as birds.…”

“…In addition, the carbon‐based nature of organic materials, and the absence of heavy metals in these devices make this technology quite environmentally friendly. In previous works, we have achieved solution‐sheared printed organic semiconductor layers with reliable charge carrier mobilities up to 12 cm 2 V −1 s −1 , [ 28 ] fully‐printed semi‐transparent all‐polymer organic field effect transistors (OFETs) working up to 48 V, [ 29 ] an audio system consisting of an OFET amplifier and a 128 cm 2 piezo‐polymer loudspeaker on plastic substrate reproducing sound pressure levels up to 60 dBA, [ 30 ] and thermally‐evaporated vertical organic transistors with a device area as small as ≈20 µm × 20 µm and small‐signal current‐gain cutoff frequency up to f T = 43.2 MHz at 9.8 V. [ 31 ] f T up to 160 MHz has been demonstrated by other groups at 40 V. [ 32 ]…”

Photolithographic Rugged Electrode for High‐Density Low‐Contact‐Resistance Coplanar Organic Transistors

“…Organic thin film transistors (OTFTs) have sparked great interest owing to their high mechanical flexibility and low cost, and have shown great application prospects in active-matrix displays, [1][2][3][4][5][6][7][8][9] smart sensors, [10,11] and logic circuits. [12][13][14][15] Coplanar architecture (bottom-contact, BC) is the most promising device configuration for high-throughput production of high-density OTFTs, [16][17][18] because this architecture is well-compatible with photolithography technique without damaging organic semiconductors. However, coplanar OTFTs generally suffer from poor charge injection, so their performance is severely limited.…”