Search results for " transistors"
showing 10 items of 54 documents
Microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions
2016
Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and this feature, together with the high carrier mobility observed, makes graphene an interesting solution for high frequency electronics. In our work, we performed a statistical analysis in order to evaluate the microwave parameters dependence on Graphene Field Effect Transistors (GFETs) dimensions. In more detail, for the first time, we studied the behavior of the cut-off frequency (ft) and of the output impedance (Zout) at varying both the gate-drain/gate-source distance (Δ) a…
Impact of GFETs geometries on RF performances
2016
Graphene is a relatively new material whose unique properties have attracted significant interest for its use in electronic and photonic applications. In particular, field effect has been proved in graphene samples and the observed high carrier mobility makes graphene an interesting solution for high frequency electronics. In this work, we focused on the analysis of microwave parameters dependence on geometries in Graphene Field Effect Transistors (GFETs). In particular, a statistical, experimental investigation of the cut-off frequency (fT) and of the output impedance (Zout) dependency on both the gate-drain/source distance (Δ) and the gate length (Lg) was carried out. 24 GFET families wer…
Infrared detection in multifunctional graphene-based transistors
2016
In the last years great attention has been paid to graphene-based devices for optoelectronic applications such as photodetection. In this work, we report on Graphene Field Effect Transistors (GFETs) photoelectrical response due to the photo-transistor effect. Photoelectrical measurements were performed using a 1.55 μm erbium fiber laser. Optical measurements as a function of both the incident laser power and the DC bias of the fabricated devices have been carried out and show that photocurrent increases with the power of the IR beam illuminating the sample.
Radiofrequency performances of different Graphene Field Effect Transistors geometries
2016
In this work, we investigated on microwave parameters geometry dependence in Graphene Field Effect Transistors (GFETs). A DC and RF characterization of the fabricated GFETs has been performed. The parametric analysis was carried out on 24 GFET families fabricated on the same chip and differing only for the channel length (Δ) and the gate length (Lg). In order to obtain a statistical average, each family included ten devices with the same geometry.Our study demonstrates that the output resistance and the cut-off frequency depend on both Δ and Lg. As expected, Rout increases with the graphene channel surface thus confirming the good quality of the fabrication procedures. An optimum region whi…
Photocurrent generation in Graphene Field Effect Transistors (GFETs)
2016
In this work, we focused on the study of Graphene Field Effect Transistors (GFETs) photoelectrical response due to the combination of photovoltaic and photo-thermoelectric effects. The technological steps for the transistors fabrication together with their electro-optic response will be presented. Measurements were performed by using a 405 nm laser diode with AM modulation at 1.33 KHz shined onto the sample under test. GFETs electrical output signals were measured by using a lock-in amplifier synchronized to the same reference frequency of the laser driver. This gave us the possibility to evaluate the optical characteristics as a function of both the incident laser power and the static pola…
Photoelectrical response of Graphene Field Effect Transistors (GFETs)
2016
In this work, we present Graphene Field Effect Transistors (GFETs) with photoelectrical response due to the photovoltaiceffect. Our final aim is to use a GFET to down convert an optical to a radiofrequency signal. The technological steps used for the devices fabrication as well as the photoelectrical characterization will be reported. Photoelectrical measurements were performed by using a 405 nm laser diode source, whose output beam was pulse amplitude-modulated at 1.33 kHz by means of a laser driver. The electrical signal out of the GFETs (in a common source amplifier configuration) was measured using a lock-in amplifier synchronized to the same reference frequency of the laser driver. Thi…
Poly(alkoxyphenylene-thienylene) Langmuir-Schäfer thin-films for advanced performance transistors
2005
Solution processed Langmuir-Scha ̈fer and cast thin films of regioregular poly(2,5-dioctyloxy-1,4- phenylene-alt-2,5-thienylene) are investigated as transistor active layers. The study of their field-effect properties evidences that no transistor behavior can be seen with a cast film channel material. This was not surprising considering the twisted conformation of the polymer backbone predicted by various theoretical studies. Strikingly, the Langmuir-Scha ̈fer (LS) thin films exhibit a field-effect mobility of 5 × 10-4 cm2/V‚s, the highest attained so far with an alkoxy-substituted conjugated polymer. Extensive optical, morphological, and structural thin-film characterization supports the a…
Bias and humidity effects on the ammonia sensing of perylene derivative/lutetium bisphthalocyanine MSDI heterojunctions
2016
International audience; In this paper, we prepared and studied sensors based on Molecular Semiconductor-Doped Insulator (MSDI) heterojunctions. These original devices are built with two stacked layers of molecular materials and exhibit very specific electrical and sensing properties. We studied the properties of a MSDI composed of the perylenetetracarboxylic dianhydride, PTCDA, or the fluorinated perylenebisimine derivative, C4F7-PTCDI, as n-type molecular material sublayers, and LuPc2 as a p-type semiconductor top layer. Their response to ammonia was compared to that of a resistor formed of only the top layer of the MSDI (LuPc2). Ammonia increases the current in the MSDIs whereas it causes…
A Very Low Band Gap Diketopyrrolopyrrole-Porphyrin Conjugated Polymer
2017
International audience; A porphyrin-diketopyrrolopyrrole-containing polymer (poly(porphyrin-diketopyrrolopyrrole) (PPDPP)) shows impressive molar absorption coefficients from lambda=300 to 1000 nm. The photophysical and structural properties of PPDPP have been studied. With PPDPP as the electron donor and [ 6,6]phenyl C-71 butyric acid methyl ester (PC71BM) as the electron acceptor, the bulk heterojunction polymer solar cell showed overall power conversion efficiencies of 4.18 and 6.44% for as-cast and two-step annealing processed PPDPP: PC71BM (1: 2) active layers, respectively. These results are quite impressive for porphyrin-containing polymers, especially when directly included in the p…
Random Structural Modification of a Low-Band-Gap BODIPY-Based Polymer
2017
International audience; A BODIPY thiophene polymer modified by extending conjugation of the BODIPY chromophore is reported. This modification induces tunability of energy levels and therefore absorption wavelengths in order to target lower energies.