Potassium Ion-Selective Field-Effect Transistor (ISFET) Sensors: Studies on Gate Dimensions and Ion-Implantation Levels

Abstract

Silicon nitride membrane ISFET sensor chips have been produced with varying gate dimensions. A series of width/length (W/L) aspect ratios have been examined, combined with three levels of boron ion-implant. The level of ion-implantation affects the threshold voltage; this is important as a low threshold voltage allows the use of low noise operating conditions. Gate dimensions are also important factors for they determine the level of drain current for a given gate and drain voltages. A novel design feature, aimed at achieving wide gates, is the use of folded gates as well as having a straight structure. The evaluation of devices with gates covered with poly(vinyl chloride) (PVC)-valinomycin-dioctyl adipate was based on their response to potassium chloride standards when it was shown that there may be a maximum width of gate above which there is no improvement of response. Also, the effect of folding the gate structure is discussed and shown to be tenable, thus permitting greater miniaturisation.     

Corannulene derivatives for organic electronics: From molecular engineering to applications

This paper intends to provide an overview for using corannulene derivatives in organic electronics such as organic field-effect transistors (OFETs), organic solar cells (OSCs), and organic light-emitting diodes (OLEDs). We highlight the rational design strategies, tuning molecular orbital energy levels and arrangement in single crystals of corannulenes. The topological structure and properties of corannulene make it a unique candidate for organic electronics.     

Flexible conducting polymer transistors with supercapacitor function

Planar organic electrochemical transistors (OECTs) using PEDOT:PSS as the channel material and nanostructured carbon (nsC) as the gate electrode material and poly(sodium 4‐styrenesulfonate (PSSNa) gel as the electrolyte were fabricated on flexible polyethylene terephthalate (Mylar^®) substrates. The nsC was deposited at room‐temperature by supersonic cluster beam deposition (SCBD). Interestingly, the OECT acts as a hybrid supercapacitor (to give a device that we indicate as transcap). The energy storage ability of transcaps has been studied with two cell configurations: one featuring PEDOT:PSS as the positive electrode and nsC as the negative electrode and another configuration with reversed electrode polarity. Potentiostatic charge/discharge studies show that both supercapacitors show good performance in terms of voltage retention, in particular, when PEDOT:PSS is used as the positive electrode. Galvanostatic charge–discharge characteristics show typical symmetric triangular shape, indicating a nearly ideal capacitive behavior with a high columbic efficiency (close to 100%). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 96–103     

High speeds complementary integrated circuits fabricated with all‐printed polymeric semiconductors

Inkjet‐printed high speed polymeric complementary circuits are fabricated using an n‐type ([poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐dithiophene)} [P(NDI2OD‐T2), Polyera ActivInk N2200] and two p‐type polymers [poly(3‐hexylthiophene) (P3HT) and a dithiophene‐based polymer (Polyera ActivInk P2100)]. The top‐gate/bottom‐contact (TG/BC) organic field‐effect transistors (OFETs) exhibit well‐balanced and very‐high hole and electron mobilities (μ_FET) of 0.2–0.5 cm²/Vs, which were enabled by optimization of the inkjet‐printed active features, small contact resistance both of electron and hole injections, and effective control over gate dielectrics and its orthogonal solvent effect (selection of poly(methyl methacrylate) and 2‐ethoxyethanol). Our first demonstrated inkjet‐printed polymeric complementary devices have been integrated to high‐performance complementary inverters (gain >30) and ring oscillators (oscillation frequency ～50 kHz). We believe that the operating frequency of printable organic circuits can be further improved more than 10 MHz by fine‐tuning of the device architecture and optimization of the p‐ and n‐channel semiconductor processing. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

High performance polymer field‐effect transistors based on polythiophene derivative with conjugated side chain

Poly(3‐[2‐(5‐hexyl‐2‐thienyl) ethenyl]‐2,2′‐bithiophene) ( P2 , see Scheme 1 ) with conjugated thienylvinyl side chain was synthesized by copolymerization of the thiophene units with and without conjugated side chain with Pd‐catalyzed Stille coupling method. For comparison, P1 with the hexyl side chain instead of conjugated side chain was also synthesized. P2 film shows broad absorption in the visible region with absorption edge at about 700 nm. The solution‐processed polymer field‐effect transistors were fabricated and characterized with bottom gate/top contact geometry. The organic field‐effect transistors (OFET) based on P2 showed an average hole mobility of about 0.034 cm²/Vs (the highest value reached 0.061 cm²/Vs) upon annealing at about 180 °C for 30 min, with a threshold voltage of ?1.15 V and an on/off ratio of 10⁴ with n‐octadecyltrichlorosilane (OTS) modified SiO₂ substrate. In comparison, the OFET based on P1 displayed a hole mobility of 8.9 × 10^–4 cm²/Vs and an on/off ratio of 10⁴ with OTS modified SiO₂ substrate. The results indicate that the polythiophene derivative with conjugated thienylvinyl side chain is a promising polymer for the application in polymer field‐effect transistors. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5304–5312, 2009     

Nonideal double-slope effect in organic field-effect transistors

With the development of device engineering and molecular design,organic field effect transistors(OFETs)with high mobility over 10 cm2 V-1-s-1 have been reported.However,the nonideal doubleslope effect has been frequently observed in some of these OFETs,which makes it difficult to extract the intrinsic mobility OFETs accurately,impeding the further application of them.In this review,the origin of the nonideal double-slope effect has been discussed thoroughly,with affecting factors such as contact resistance,charge trapping,disorder effects and coulombic interactions considered.According to these discussions and the understanding of the mechanism behind double-slope effect,several strategies have been proposed to realize ideal OFETs,such as doping,molecular engineering,charge trapping reduction,and contact engineering.After that,some novel devices based on the nonideal double-slope behaviors have been also introduced.     

Improved charge transport and trap-state distribution in donor–acceptor-type semiconducting copolymer with a fluoropolymer dielectric film

This study presents a p-type doping method for donor–acceptor-type conjugated semiconducting copolymer-based field-effect transistors (FETs) with a fluoropolymer dielectric film. The polymeric FET, which initially comprises a non-polar polymer dielectric layer (poly (methyl methacrylate), PMMA), shows ambipolar behavior owing to the well-balanced electron-accepting and -donating properties of the cyclopentadithiophene (CDT) and pyridyl-2,1,3-thiadiazole (PTz)-based conjugated polymer backbone system. However, when combined with an amorphous fluoropolymer (CYTOP) dielectric layer, the FET device exhibits that their ambipolar behavior remarkably changes to a high-performance p-type FET; the hole mobility enhanced by a factor of ~3 and the threshold voltage significantly shifted from −29 V to −12 V. The density of trap states in the CDT-PTz-based polymeric FETs with a CYTOP dielectric layer, which was estimated from the temperature-dependent transfer characteristics, was narrower and shallower than that of polymeric FETs with a PMMA dielectric layer. As such, it can be inferred that the deep-trap states are filled with additional doped charges from the surface polarization induced by the fluorinated dielectrics at the semiconductor-dielectric interface.