A general model to describe the electrostatic potential at electrolyte oxide interfaces

Hal, R.E.G. van; Eijkel, Jan C.T.; Bergveld, Piet

doi:10.1016/s0001-8686(96)00307-7

Cited by 352 publications

(325 citation statements)

References 12 publications

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“…The behavior of the device on bare quartz is reproduced by the parameters N S = 1.02 ± 0.11 10 16 cm -2 , Q int = 2.69 ± 0.24 µC and α = -15.5 ± 1.7 mV. The value of Ns is in agreement with other models; 26,27 if the channel area is A ch = 3.02 10 33 cm 2 and the thickness of pentacene is 15 nm, Q int corresponds to a maximum density of dopants (each deproto3 nated site yields a charge in pentacene) of approximately 4 10 20 cm -3 , i.e. 4 charges per 14 unit cells.…”

Section: Acs Applied Materials and Interfacessupporting

confidence: 84%

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The Substrate is a pH-Controlled Second Gate of Electrolyte-Gated Organic Field-Effect Transistor

Lauro

Casalini

Berto

et al. 2016

ACS Appl. Mater. Interfaces

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Electrolyte3gated organic field3effect transistors (EGOFETs), based on ultra3thin pentacene films on quartz, were operated with electrolyte solutions whose pH was systematically changed. Transistor parameters exhibit non3monotonic variation vs pH, which cannot be accounted for by capacitive coupling through the Debye3Helmholtz layer. The data were fitted with an ana3 lytical model of the accumulated charge in the EGOFET where Langmuir adsorption was introduced to describe the (pH3 dependent) charge build3up at the quartz surface. The model provides an excellent fit to the threshold voltage and transfer charac3 teristics as a function of pH, which demonstrates that quartz acts as a second gate controlled by pH, and is mostly effective at neu3 tral or alkaline pH. The effective capacitance of the device is always greater than the capacitance of the electrolyte, thus highlight3 ing the role of the substrate as an important active element for amplification of the transistor response. INTRODUCTIONSince the pioneering work of Bergveld 1 several examples of field3effect transistors (FETs) have been demonstrated as sen3 sors working in aqueous solutions. 2 In the ion3sensing field3 effect transistor (ISFET), a reference electrode controls the potential of an electrolyte solution at the interface with a met3 al3oxide3semiconductor FET (MOSFET). The ISFET is a po3 tentiometric sensor that responds to the activity of ions, in par3 ticular hydronium ions, at the electro3 lyte/dielectric/semiconductor interface. Ion3sensitive organic field3effect transistors (ISOFETs) were also demonstrated, where the channel consists of an organic semiconductor (OSC) thin film. 3,4 In these architectures, an encapsulation layer sepa3 rating the organic semiconductor thin film from the aqueous environment has been used. Both inorganic (e.g. silicon ni3 tride 3 and tantalum pentoxide 4 ) and organic (e.g. poly(methyl methacrylate) 5 and poly(vinylidene fluoride)) 6 dielectrics were exploited to yield pH3sensitive devices. It is also possible to operate the IS(O)FET in a dual gate archi3 tecture, where the bottom gate consists of a metal electrode separated by a (bottom) dielectric, and the top gate electrode controls the bath potential. The two gates are operated inde3 pendently, giving rise to a dual channel in a thick film (if the signs of gate voltages are the same) or depleting one of the channels (if their signs are opposite). It was shown 7,8 that the device responds with a shift of threshold voltage to changes of the top3gate potential. The shift observed is proportional to (the negative of) the potential change at the top gate, through a capacitive coupling given by the ratio of the top and bottom

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Section: Acs Applied Materials and Interfacessupporting

confidence: 84%

“…In eq 9, following van Hal et al, 26 a linear dependence of Ψ B on pH (in our observed range) is assumed through the coeffi3 cient α. The total charge Q P5 , as well as the charge contributed by the quartz surface Q q and the capacitive charge Q 1 are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

The Substrate is a pH-Controlled Second Gate of Electrolyte-Gated Organic Field-Effect Transistor

Lauro

Casalini

Berto

et al. 2016

ACS Appl. Mater. Interfaces

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“…According to the site binding model of EDL, 45 Further increase in pH value leads to decrease in noise PSD. The maximum noise PSD level appears pH~5, which is close to the point of zero charge of SiN x .…”

Section: Origin Of the Nanopore Flicker Noisementioning

confidence: 99%

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

et al. 2017

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Nanopore technology has been extensively investigated for analysis of biomolecules, and a success story in this field concerns DNA sequencing using a nanopore chip featuring an array of hundreds of biological nanopores (BioNs). Solid-state nanopores (SSNs) have been explored to attain longer lifetime and higher integration density than what BioNs can offer, but SSNs are generally considered to generate higher noise whose origin remains to be confirmed. Here, we systematically study low-frequency (including thermal and flicker) noise characteristics of SSNs measuring 7 to 200 nm in diameter drilled through a 20-nm-thick SiN x membrane by focused ion milling. Both bulk and surface ionic currents in the nanopore are found to contribute to the flicker noise, with their respective contributions determined by salt concentration and pH in electrolytes as well as bias conditions. Increasing salt concentration at constant pH and voltage bias leads to increase in the bulk ionic current and noise therefrom. Changing pH at constant salt concentration and current bias results in variation of surface charge density, and hence alteration of surface ionic current and noise. In addition, the noise from Ag/AgCl electrodes can become predominant when the pore size is large and/or the salt concentration is high. Analysis of our comprehensive experimental results leads to the establishment of a generalized nanopore noise model. The model not only gives an excellent account of the experimental observations, but can also be used for evaluation of various noise components in much smaller nanopores currently not experimentally available.

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“…are those of a capacitance, describing the sensitivity of the surface charge to a change in the local potential, which is sometimes denoted as regulation capacitance [10] or a surface buffer capacitance [26]. In the following, we will denote the nondimensional form of this capacitance as…”

Section: Modelmentioning

confidence: 99%