Contact-resistance effects in PDI8-CN 2  n-type thin-film transistors investigated by Kelvin-probe potentiometry

Chiarella, F.; Barra, Mario; Carella, Antonio; Parlato, L.; Sarnelli, E.; Cassinese, A.

doi:10.1016/j.orgel.2015.11.009

Cited by 30 publications

(21 citation statements)

References 30 publications

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“…The trend of R C versus V DS has not been as extensively studied as R C versus V GS , but through SKPM Chiarella et al found that R C decreased with increasing V DS in an exponential fashion . Contact resistance had a stronger dependence on V DS than V GS , a trend also found by Chianese et al Furthermore, both studies found that R D was substantially greater than R S , indicating that their n‐type devices were not injection limited as expected of a device with high R C …”

Section: Characterizing Contact Resistance In Ofetsmentioning

confidence: 87%

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Waldrip

Jurchescu

Gundlach

et al. 2019

Adv Funct Materials

219

261

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Organic semiconductors have sparked interest as flexible, solution processable, and chemically tunable electronic materials. Improvements in charge carrier mobility put organic semiconductors in a competitive position for incorporation in a variety of (opto-)electronic applications. One example is the organic field-effect transistor (OFET), which is the fundamental building block of many applications based on organic semiconductors. While the semiconductor performance improvements opened up the possibilities for applying organic materials as active components in fast switching electrical devices, the ability to make good electrical contact hinders further development of deployable electronics. Additionally, inefficient contacts represent serious bottlenecks in identifying new electronic materials by inhibiting access to their intrinsic properties or providing misleading information. Recent work focused on the relationships of contact resistance with device architecture, applied voltage, metal and dielectric interfaces, has led to a steady reduction in contact resistance in OFETs. While impressive progress was made, contact resistance is still above the limits necessary to drive devices at the speed required for many active electronic components. Here, the origins of contact resistance and recent improvement in organic transistors are presented, with emphasis on the electric field and geometric considerations of charge injection in OFETs.semiconductors with superior intrinsic charge transport properties, there is a stringent need to improve the device properties in order to allow organic devices to fulfill their technological prospectives. In the organic semiconductor community, contact resistance (R C ) has come under increased scrutiny as it is apparent that the final device performance is often domi nated by carrier injection, rather than the transport through the semiconductor layer. Contact resistance can impact OFET development in multiple ways. First, if not accounted for, a high contact resistance may lead to inaccurate extraction of the device parameters. Second, any inaccuracies in parameter extraction can have significant consequences on material development, from generating incorrect structure-property relationships to discarding organic semiconductors whose efficient intrinsic electrical properties have been masked by inefficient contacts. Beyond OFET and semiconductor characterization, analog, low power, and high frequency applications require a greater level of device parameter control than has been obtained in typical DC, high-voltage OFETs. For analog applications, e.g., integration of conditioning circuits such as local sense amps for distributed flexible sensor arrays, nonlinearity of the transistor response inhibits proper functioning and limits applicability of common models used to design circuitry. Low power device development for novel materials are hindered by the high voltage turn-on and current suppression in devices with large R C . Considering high-frequency applications, Klauk suggest...

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Section: Characterizing Contact Resistance In Ofetsmentioning

confidence: 87%

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Waldrip

Jurchescu

Gundlach

et al. 2019

Adv Funct Materials

219

261

View full text Add to dashboard Cite

show abstract

“…Other groups have measured the built-in potential of single-layer MoS 2 heterojunctions using KPFM [30] and demonstrated the electrical properties of the contact between MoS 2 and different metals [31]. These measurements resemble the use of KPFM for contact resistance evaluation [32] and contact-free mobility estimation [33] in thin-film organic transistors.…”

Section: Introductionmentioning

confidence: 99%

Pinch-Off Formation in Monolayer and Multilayers MoS2 Field-Effect Transistors

2019

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The discovery of layered materials, including transition metal dichalcogenides (TMD), gives rise to a variety of novel nanoelectronic devices, including fast switching field-effect transistors (FET), assembled heterostructures, flexible electronics, etc. Molybdenum disulfide (MoS2), a transition metal dichalcogenides semiconductor, is considered an auspicious candidate for the post-silicon era due to its outstanding chemical and thermal stability. We present a Kelvin probe force microscopy (KPFM) study of a MoS2 FET device, showing direct evidence for pinch-off formation in the channel by in situ monitoring of the electrostatic potential distribution along the conducting channel of the transistor. In addition, we present a systematic comparison between a monolayer MoS2 FET and a few-layer MoS2 FET regarding gating effects, electric field distribution, depletion region, and pinch-off formation in such devices.

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“…Taking inspiration from a previous work by the Northwestern University's group [67], we also verified, for PDI8-CN2 transistors, the possibility to reduce the impact of the contact resistance effect by using a suitable functionalization of the gold electrodes with a 4-chlorobenzenemethanethiol self-assembling monolayer. Despite a beneficial effect being unambiguously verified in this way, the overall reduction of RC was quite limited to a factor between 30% and 15% depending on the film thickness [62]. Supplementary efforts were carried out to investigate the RC behavior as a function of temperature.…”

Section: R C Evaluation Using Kelvin Probe Microscopymentioning

confidence: 90%

“…Further SKPM measurements also demonstrated that R C effects tend to be magnified when the thickness of the organic layer is decreased down to 10 nm. As an example, for the PDI8-CN 2 OFET, the R C value is enhanced by a factor larger than 5× when the organic layer thickness goes from 20 to 6 nm [62]. Taking inspiration from a previous work by the Northwestern University's group [67], we also verified, for PDI8-CN 2 transistors, the possibility to reduce the impact of the contact resistance effect by using a suitable functionalization of the gold electrodes with a 4-chlorobenzenemethanethiol self-assembling monolayer.…”

Section: R C Evaluation Using Kelvin Probe Microscopymentioning

confidence: 99%

“…In this way, the contributions of source and drain electrodes can be directly and separately measured, in contrast with alternative techniques such as the transmission line method (TLM) and the gated four-probe configuration [58]. Motivated by the substantial lack of SKPM data reported for n-type devices, we performed a systematic analysis of the R C effects in PDI8-CN 2 and PDIF-CN 2 thin-film bottom-contact transistors [62,63]. Our attention was basically focused on devices fabricated by the OMBD technique on HMDS-treated SiO 2 substrates and in the optimized conditions.…”

Section: R C Evaluation Using Kelvin Probe Microscopymentioning

confidence: 99%

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Perylene-Diimide Molecules with Cyano Functionalization for Electron-Transporting Transistors

et al. 2019

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Core-cyanated perylene diimide (PDI_CY) derivatives are molecular compounds exhibiting an uncommon combination of appealing properties, including remarkable oxidative stability, high electron affinities, and excellent self-assembling properties. Such features made these compounds the subject of study for several research groups aimed at developing electron-transporting (n-type) devices with superior charge transport performances. After about fifteen years since the first report, field-effect transistors based on PDI_CY thin films are still intensely investigated by the scientific community for the attainment of n-type devices that are able to balance the performances of the best p-type ones. In this review, we summarize the main results achieved by our group in the fabrication and characterization of transistors based on PDI8-CN2 and PDIF-CN2 molecules, undoubtedly the most renowned compounds of the PDI_CY family. Our attention was mainly focused on the electrical properties, both at the micro and nanoscale, of PDI8-CN2 and PDIF-CN2 films deposited using different evaporation techniques. Specific topics, such as the contact resistance phenomenon, the bias stress effect, and the operation in liquid environment, have been also analyzed.

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Contact-resistance effects in PDI8-CN 2 n-type thin-film transistors investigated by Kelvin-probe potentiometry

Cited by 30 publications

References 30 publications

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Pinch-Off Formation in Monolayer and Multilayers MoS2 Field-Effect Transistors

Perylene-Diimide Molecules with Cyano Functionalization for Electron-Transporting Transistors

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