Search results for "Transistor"
showing 10 items of 234 documents
Experimental investigation of the kink effect and the low frequency noise properties in pseudomorphic HEMT’s
2005
The kink effect in low-noise pseudomorphic (AlGaAs/InGaAs) HEMT's has been examined in detail by investigating the steady-state and pulsed I-V characteristics, the behavior of the output conductance dispersion and the performance of the gate leakage current to understand its origin. No clear evidence of impact ionization occurrence in the InGaAs channel at kink bias conditions (V-DS.kink = 1.5 V) has been found, thus suggesting that the predominant mechanism should be attributed to trap-related phenomena. A significant rise of the gate current has been found at very high drain voltages (far from V-DS.kink) associated with low drain current values which is probably due to impact ionization o…
Current injection from metal to MoS2 probed at nanoscale by conductive atomic force microscopy
2016
Contacts with MoS2 are currently the object of many investigations, since current injection through metal/MoS2 interfaces represents one of the limiting factors to the performance of MoS2 thin film transistors. In this paper, we employed conductive atomic force microscopy (CAFM) to investigate the current injection mechanisms from a nanometric contact (a Pt coated tip) to the surface of MoS2 thin films exfoliated on SiO2. The analysis of local current-voltage (I-V) characteristics on a large array of tip positions provided high spatial resolution information on the lateral homogeneity of the tip/MoS2 Schottky barrier Phi(B) and of the ideality factor n. From the histograms of the measured P…
High-Frequency Experimental Characterization and Modeling of Six Pack IGBTs Power Modules
2016
In this paper, a method to characterize the high-frequency (HF) behavior of six pack insulated gate bipolar transistors (IGBTs) power module (PM) is presented. The method is based on experimental measurements at the external pins of the device and it allows one to extract internal inductive and capacitive parasitic coupling without the knowledge of structural and physical parameters of the PM. The HF model of a six pack IGBTs PM has been developed, in the frequency range of 150 kHz-30 MHz, and it has been implemented in MATLAB environment. The method has been experimentally validated by comparing the frequency behavior of the PM with the simulated response. Moreover, the HF conducted distur…
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…
Layered Thiadiazoloquinoxaline-Containing Long Pyrene-Fused N-Heteroacenes
2018
Three thiadiazoloquinoxaline-containing long pyrene-fused N-heteroacenes with 8, 13, and 18 rings were designed and synthesized. They show high electron affinities (EAs) of approximately 4.1 eV, which were derived from the onset of the reduction peaks in cyclic voltammetry. Crystal structure analysis revealed in-plane extension through close contacts between thiadiazole units as well as layered packing, enabling in-plane and interlayer electron transport. Organic field-effect transistor devices provided electron mobilities, which suggest a potential way to enhance the charge transport in long N-heteroacenes.
Effect of temperature–bias annealing on the hysteresis and subthreshold behavior of multilayer MoS2 transistors
2016
The transfer characteristics (ID-VG) of multilayers MoS2 transistors with a SiO2/Si backgate and Ni source/drain contacts have been measured on as-prepared devices and after annealing at different temperatures (T-ann from 150 degrees C to 200 degrees C) under a positive bias ramp (V-G from 0 V to + 20 V). Larger T-ann resulted in a reduced hysteresis of the ID-VG curves (from similar to 11 V in the as-prepared sample to similar to 2.5 V after Tann at 200 degrees C). The field effect mobility (similar to 30 cm(2) V-1 s(-1)) remained almost unchanged after the annealing. On the contrary, the subthreshold characteristics changed from the common n-type behaviour in the as-prepared device to the…
Charge transport mechanism in networks of armchair graphene nanoribbons
2020
In graphene nanoribbons (GNRs), the lateral confinement of charge carriers opens a band gap, the key feature to enable novel graphene-based electronics. Successful synthesis of GNRs has triggered efforts to realize field-effect transistors (FETs) based on single ribbons. Despite great progress, reliable and reproducible fabrication of single-ribbon FETs is still a challenge that impedes applications and the understanding of the charge transport. Here, we present reproducible fabrication of armchair GNR-FETs based on a network of nanoribbons and analyze the charge transport mechanism using nine-atom wide and, in particular, five-atom-wide GNRs with unprecedented conductivity. We show formati…
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.