Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

Held, Martin; Schießl, Stefan P.; Miehler, Dominik; Gannott, Florentina; Zaumseil, Jana

doi:10.1063/1.4929461

Cited by 54 publications

(51 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A hybrid dielectric, consisting of ~11 nm poly(methyl methacrylate) (PMMA) and a ~61 nm layer of hafnium oxide (HfOx) on top, was chosen to achieve low gate leakage currents and to permit low-voltage operation. 47 To complete the devices, a semi-transparent 20 nm silver gate electrode was thermally evaporated onto the dielectric through a shadow mask. All devices exhibited ambipolar charge transport with low leakage currents and high on/off ratios on the order of 10 5 -10 6 as shown in the transfer characteristics at low source-drain bias (Vd = -0.1 V¸ Figure 1e) and the respective output curves (see Supporting Information, Figure S4).…”

Section: Resultsmentioning

confidence: 99%

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

et al. 2020

Self Cite

View full text Add to dashboard Cite

Solution-processed networks of semiconducting, single-walled carbon nanotubes (SWCNTs) have attracted considerable attention as materials for next-generation electronic devices and circuits. However, the impact of the SWCNT network composition on charge transport on a microscopic level remains an open and complex question. Here, we use charge-modulated absorption and photoluminescence spectroscopy to probe exclusively the mobile charge carriers in monochiral (6,5) and mixed SWCNT network field-effect transistors. Ground state bleaching and charge-induced trion absorption features, as well as exciton quenching are observed depending on applied voltage and modulation frequency. Through correlation of the modulated mobile carrier density and the optical response of the nanotubes, we find that charge transport in mixed SWCNT networks depends strongly on the diameter and thus bandgap of the individual species. Mobile charges are preferentially transported by small bandgap SWCNTs especially at low gate voltages, whereas large bandgap species only start to participate at higher carrier concentrations. Our results demonstrate the excellent suitability of modulation spectroscopy to investigate charge transport in nanotube network transistors and highlight the importance of SWCNT network composition for their performance.KEYWORDS single-walled carbon nanotubes, networks, charge transport, charge modulation spectroscopy, photoluminescence, trionSemiconducting single-walled carbon nanotubes (SWCNTs) have emerged as a promising material for future electronic applications as they combine high charge carrier mobilities with mechanical flexibility and solution-processability. 1, 2 Stimulated by the major progress in sorting techniques such as gel chromatography, 3, 4 density gradient ultracentrifugation, 5 aqueous two-phase separation, 6 and polymer-wrapping, 7-9 the reproducible fabrication of highperformance field-effect transistors (FETs) and circuits based on networks of purely semiconducting SWCNTs has become feasible. [10][11][12][13][14][15][16] Nonetheless, charge transport in nanotube networks is not yet fully understood especially regarding mixed networks of nanotube species with varying compositions. 17, 18 A detailed understanding of the fundamental transport parameters is necessary to further optimize effective carrier mobilities for competitive network devices at a minimum cost for purification.Charge transport in semiconductors is commonly studied through temperature-dependent measurements of conductivities and carrier mobilities. 17, 19-21 However, these techniques cannot distinguish between different SWCNT species and thus are not suitable to examine the chirality-dependent contributions to the macroscopic device performance. Given the high sensitivity of SWCNT absorption and emission features to charge carriers, which was shown in several studies, 22-25 electro-optical methods could provide additional and even chiralityspecific insights. For example, based on the analysis of the E11 absorption band change of...

show abstract

Section: Resultsmentioning

confidence: 99%

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Significantly, there exist multiple reports demonstrating a dielectric dependence to the charge mobility of semiconductors. 11,12 Yet, the mechanisms used to explain these differences vary greatly, from templated growth, 13 to interfacial trap states, 14 and planarization of the interface. 15 In this work, we present a direct comparison of In 2 O 3 TFTs and dielectric-only capacitors, produced with single and double layers of three different materials namely; AlO x , HfO x and ZrO x .…”

confidence: 99%

“…11,12,15 Each of these three mechanisms 2018) can affect the carrier mobility within the channel of a TFT, and all are dependent on the quality of the interface between the dielectric and semiconductor. Interface trap states are specifically due to the bonding interaction between semiconductor and dielectric.…”

confidence: 99%

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

et al. 2018

View full text Add to dashboard Cite

The quality of the gate dielectric/semiconductor interface in thin-film transistors (TFTs) is known to determine the optimum operating characteristics attainable. As a result in recent years the development of methodologies that aim to improve the channel interface quality has become a priority. Herein, we study the impact of the surface morphology of three solution-processed high-k metal oxide dielectrics, namely AlOx, HfOx, and ZrOx, on the operating characteristics of In2O3 TFTs. Six different dielectric configurations were produced via single or double-step spin-casting of the various precursor formulations. All layers exhibited high areal capacitance in the range of 200 to 575 nF/cm2, hence proving suitable, for application in low-voltage n-channel In2O3 TFTs. Study of the surface topography of the various layers indicates that double spin-cast dielectrics exhibit consistently smoother layer surfaces and yield TFTs with improved operating characteristics manifested, primarily, as an increase in the electron mobility (µ). To this end, µ is found to increase from 1 to 2 cm2/Vs for AlOx, 1.8 to 6.4 cm2/Vs for HfOx, and 2.8 to 18.7 cm2/Vs for ZrOx-based In2O3 TFTs utilizing single and double-layer dielectric, respectively. The proposed method is simple and potentially applicable to other metal oxide dielectrics and semiconductors.

show abstract

“…Here we used an ambipolar LEFET structure and integrated it in a planar Fabry–Pérot microcavity as schematically shown in Figure b. After evaporation of the gold bottom mirror on a glass substrate, an insulating AlO x spacer layer was deposited, gold source and drain electrode were patterned, followed by spin‐coating of the DPPT‐BT, deposition of the hybrid poly[methyl methacrylate](PMMA)/hafnium oxide (HfO x ) dielectric and a silver top gate that also acted as the top mirror.…”

Section: Resultsmentioning

confidence: 99%

Ultrastrong Coupling of Electrically Pumped Near‐Infrared Exciton‐Polaritons in High Mobility Polymers

Held

Graf

Zakharko

et al. 2017

Advanced Optical Materials

Self Cite

View full text Add to dashboard Cite

two new hybridized modes appear-the upper (UP) and lower polariton (LP). These manifest in a characteristic anticrossing of the almost dispersionless exciton and the parabolic photon dispersion. From the dispersion of the polariton modes, the coupling potential (V A ), which is proportional to the observed minimal splitting between UP and LP, can be deduced. Organic materials favor particularly high coupling potentials (V A > 100 meV) due to their large oscillator strength and are ideal to create exciton-polaritons at room-temperature due to their large exciton binding energies. [1][2][3][4] The unique combination of both light and matter character in excitonpolaritons results in fascinating properties, for example, polaritons can reach a macroscopic occupation of the ground state (condensation) at room-temperature with coherent light emission, so-called polariton lasing, at lower thresholds than conventional photon lasing. [5][6][7][8][9] They may also affect chemical reactions and there have been suggestions that they can even influence charge transport. [10,11] Polariton emission typically occurs from the LP branch due to relaxation enabled by the excitonic character of the polaritons. Owing to their hybrid excitonic-photonic character, the emission linewidth of the LP is typically narrowed for many organic systems and can be spectrally tuned by adjusting the cavity resonance. [4] Further, if the coupling potential of the hybrid system exceeds about 20% of the exciton energy, the regime of ultrastrong coupling is reached, for which new intriguing phenomena are predicted and have also been observed to some extent. [12][13][14][15] Emission from the lower polariton in the ultrastrong coupling regime shows very low dispersion and thus minimal angular color shift while maintaining the narrow linewidth of the mixed state. [13,16] This feature makes the ultrastrong coupling regime attractive for color-pure emission from electrically driven lightemitting devices. Semiconducting donor-acceptor polymers show unusually high oscillator strength at low photon energies [17] and are thus ideal materials to achieve ultrastrong coupling. At the same time these polymers exhibit large ambipolar charge carrier mobilities, which render them interesting for electrical generation of exciton-polaritons. [18,19] In previous work light-emitting diode (LED) structures were used to achieve electrically driven exciton-polariton emission. In these structures, the cavity mirrors also acted as the injection electrodes. [15,[20][21][22][23][24] In case of organic LEDs (OLEDs), metallic anodes and cathodes (e.g., silver or aluminum) were Exciton-polaritons are quasiparticles with hybrid light-matter properties that may be used in new optoelectronic devices. Here, electrically pumped ultrastrongly coupled exciton-polaritons in a high-mobility donor-acceptor copolymer are demonstrated by integrating a light-emitting field-effect transistor into a metal-clad microcavity. Near-infrared electroluminescence is emitted exclusively from the lower pol...

show abstract

Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

Cited by 54 publications

References 29 publications

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

Ultrastrong Coupling of Electrically Pumped Near‐Infrared Exciton‐Polaritons in High Mobility Polymers

Contact Info

Product

Resources

About