Hybrid bilayer membrane (HBM) was prepared on solid substrates by coupling self-assembly with ves... more Hybrid bilayer membrane (HBM) was prepared on solid substrates by coupling self-assembly with vesicle fusion methods. The prepared HBM films were examined by cyclic voltammetry and scanning tunneling microscope (STM) measurements. The HBM films composed of octadecanthiol (C18H37SH) and phosphatidylcholine (C44H88NO8P) showed resistance to chemical-reduced reactions. STM observations revealed a change in the surface morphology of the HBM by an
ABSTRACT A silver nanoparticles self-assembled monolayer was incorporated in pentacene field-effe... more ABSTRACT A silver nanoparticles self-assembled monolayer was incorporated in pentacene field-effect transistors and their memory effects were investigated using the current–voltage measurement. The results showed that there was a significant shift in threshold voltage under different writing and erasing voltages applied on the gate electrode and the memory window changed accordingly with mentioned applied voltage bias. Charge retention time was estimated up to 2000 s even under different biased voltages. On the other hand, the reference OFETs without a nanoparticle layer exhibited no memory effects. Further, accelerated aging study of the organic transistors with nanoparticles revealed the conservation of memory window.
We investigated the injection and transport properties of pentacene organic field-effect transist... more We investigated the injection and transport properties of pentacene organic field-effect transistors (OFETs) with inclined and lamellar pentacene grains at various mutual ratios. Although the threshold voltage was conserved and no additional trapping on grain boundaries was suggested from the current–voltage measurements, the contact resistance and mobility increased linearly with the lamellar phase content. We showed that a model based on the coupling between both transport and injection properties via a space charge field caused by injected and trapped carriers accounts for these results.
ABSTRACT Here we report a dielectric approach to verify the channel dependence of the threshold v... more ABSTRACT Here we report a dielectric approach to verify the channel dependence of the threshold voltage in organic field-effect transistors (OFETs). This approach is based on dielectrics physics, and it shows that the potential drop on the injection electrode reduces the capability of applied voltage to accumulate charges that contribute to carrier transport along the channel, which is interpreted as a shift of the threshold voltage. That is, contact resistance is an origin of the channel-length-dependent threshold voltage.
ABSTRACT A silver nanoparticles self-assembled monolayer (SAM) was incorporated in pentacene fiel... more ABSTRACT A silver nanoparticles self-assembled monolayer (SAM) was incorporated in pentacene field-effect transistor and its effects on the carrier injection and transport were investigated using the current-voltage (I − V) and impedance spectroscopy (IS) measurements. The I − V results showed that there was a significant negative shift of the threshold voltage, indicating the hole trapping inside the devices with about two orders higher in the contact resistance and an order lower in the effective mobility when a SAM was introduced. The IS measurements with the simulation using a Maxwell-Wagner equivalent circuit model revealed the existence of multiple trapping states for the devices with NPs, while the devices without NPs exhibited only a single trap state.
The effect of silver nanoparticles self-assembled monolayer (Ag NPs SAM) on charge transport in p... more The effect of silver nanoparticles self-assembled monolayer (Ag NPs SAM) on charge transport in pentacene organic field-effect transistors (OFET) was investigated by both steady-state and transient-state methods, which are current-voltage measurements in steady-state and time-resolved microscopic (TRM) second harmonic generation (SHG) in transient-state, respectively. The analysis of electronic properties revealed that OFET with SAM exhibited significant charge trapping effect due to the space-charge field formed by immobile charges. Lower transient-state mobility was verified by the direct probing of carrier motion by TRM-SHG technique. It was shown that the trapping effect rises together with increase of SAM layers suggesting the presence of traps in the bulk of NP films. The model based on the electrostatic charge barrier is suggested to explain the phenomenon.
Hybrid bilayer membrane (HBM) was prepared on solid substrates by coupling self-assembly with ves... more Hybrid bilayer membrane (HBM) was prepared on solid substrates by coupling self-assembly with vesicle fusion methods. The prepared HBM films were examined by cyclic voltammetry and scanning tunneling microscope (STM) measurements. The HBM films composed of octadecanthiol (C18H37SH) and phosphatidylcholine (C44H88NO8P) showed resistance to chemical-reduced reactions. STM observations revealed a change in the surface morphology of the HBM by an
ABSTRACT A silver nanoparticles self-assembled monolayer was incorporated in pentacene field-effe... more ABSTRACT A silver nanoparticles self-assembled monolayer was incorporated in pentacene field-effect transistors and their memory effects were investigated using the current–voltage measurement. The results showed that there was a significant shift in threshold voltage under different writing and erasing voltages applied on the gate electrode and the memory window changed accordingly with mentioned applied voltage bias. Charge retention time was estimated up to 2000 s even under different biased voltages. On the other hand, the reference OFETs without a nanoparticle layer exhibited no memory effects. Further, accelerated aging study of the organic transistors with nanoparticles revealed the conservation of memory window.
We investigated the injection and transport properties of pentacene organic field-effect transist... more We investigated the injection and transport properties of pentacene organic field-effect transistors (OFETs) with inclined and lamellar pentacene grains at various mutual ratios. Although the threshold voltage was conserved and no additional trapping on grain boundaries was suggested from the current–voltage measurements, the contact resistance and mobility increased linearly with the lamellar phase content. We showed that a model based on the coupling between both transport and injection properties via a space charge field caused by injected and trapped carriers accounts for these results.
ABSTRACT Here we report a dielectric approach to verify the channel dependence of the threshold v... more ABSTRACT Here we report a dielectric approach to verify the channel dependence of the threshold voltage in organic field-effect transistors (OFETs). This approach is based on dielectrics physics, and it shows that the potential drop on the injection electrode reduces the capability of applied voltage to accumulate charges that contribute to carrier transport along the channel, which is interpreted as a shift of the threshold voltage. That is, contact resistance is an origin of the channel-length-dependent threshold voltage.
ABSTRACT A silver nanoparticles self-assembled monolayer (SAM) was incorporated in pentacene fiel... more ABSTRACT A silver nanoparticles self-assembled monolayer (SAM) was incorporated in pentacene field-effect transistor and its effects on the carrier injection and transport were investigated using the current-voltage (I − V) and impedance spectroscopy (IS) measurements. The I − V results showed that there was a significant negative shift of the threshold voltage, indicating the hole trapping inside the devices with about two orders higher in the contact resistance and an order lower in the effective mobility when a SAM was introduced. The IS measurements with the simulation using a Maxwell-Wagner equivalent circuit model revealed the existence of multiple trapping states for the devices with NPs, while the devices without NPs exhibited only a single trap state.
The effect of silver nanoparticles self-assembled monolayer (Ag NPs SAM) on charge transport in p... more The effect of silver nanoparticles self-assembled monolayer (Ag NPs SAM) on charge transport in pentacene organic field-effect transistors (OFET) was investigated by both steady-state and transient-state methods, which are current-voltage measurements in steady-state and time-resolved microscopic (TRM) second harmonic generation (SHG) in transient-state, respectively. The analysis of electronic properties revealed that OFET with SAM exhibited significant charge trapping effect due to the space-charge field formed by immobile charges. Lower transient-state mobility was verified by the direct probing of carrier motion by TRM-SHG technique. It was shown that the trapping effect rises together with increase of SAM layers suggesting the presence of traps in the bulk of NP films. The model based on the electrostatic charge barrier is suggested to explain the phenomenon.
Uploads
Papers by Takaaki Manaka