Schottky Barrier (schottky + barrier)

Distribution by Scientific Domains

Terms modified by Schottky Barrier

  • schottky barrier diode

  • Selected Abstracts

    An Individual Carbon Nanotube Transistor Tuned by High Pressure

    Christophe Caillier
    Abstract A transistor based on an individual multiwalled carbon nanotube is studied under high-pressure up to 1 GPa. Dramatic effects are observed, such as the lowering of the Schottky barrier at the gold,nanotube contacts, the enhancement of the intertube conductance, including a discontinuity related to a structural transition, and the decrease of the gate hysteresis of the device. [source]

    Interface Atomic-Scale Structure and its Impact on Quantum Electron Transport

    ADVANCED MATERIALS, Issue 48 2009
    Zhongchang Wang
    Local structure, chemistry, and bonding at interfaces often radically affect the properties of materials. A combination of scanning transmission electron microscopy and density functional theory calculations reveals an atomic layer of carbon at a SiC/Ti3SiC2 interface in Ohmic contact to p-type SiC (see image), which results in stronger adhesion, a lowered Schottky barrier, and enhanced transport. This is a key factor to understanding the origin of the Ohmic nature. [source]

    Optimization of the ohmic contact processing in InAlN//GaN high electron mobility transistors for lower temperature of annealing

    Abstract In this article, we optimized the ohmic contact processing in InAlN/GaN high electron mobility transistors for the lower temperature of annealing by recessing of metalliza-tion to approach the 2DEG at the InAlN/GaN interface. The ohmic contacts which were recessed down to 5 nm depth and annealed at 700 C 2 min. exhibited the contact resistance of 0,39 ,mm while the channel sheet resistance was 210 ,/square. These values are comparative to values of contacts processed at more conventional an-nealing conditions (800 C, 2 min). Moreover we applied the recessed ohmic contact technology to fabricate Schottky barrier (SB) HEMTs and MOSHEMTs with Al2O3 dielectric film. For MOSHEMTs, we measured the maximal reduction of the gate leakage current by about 6 orders of magnitude if compared with SB HEMTs. The maximal drain current of MOSHEMTs was about 750 mA/mm at VGS = 0 V and the maximal extrinsic transconductance (gme) reached 101 mS/mm. ( 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Impact of native oxides beneath the gate contact of AlGaN/GaN HFET devices

    D. Mistele
    Abstract We report on the decisive role of oxides at the surface of AlGaN/GaN Heterostructure Field Effect Transistors (HFETs). The effect of oxides at the surface is twofold, on one hand the 2DEG in the channel is directly influenced by surface charges and surface potential correlated to surface oxides (D. Mistele et al., phys. stat. sol. (a) 194 (2), 452 (2002). [1]), on the other hand, a surface oxide below a subsequently deposited gate contact increases the barrier height and therefore reduces leakage currents by several orders of magnitude. This study includes various surface treatments on AlGaN/GaN heterostructures such as etching by HCl, oxidation by O2 -plasma, and subsequent passivation by Si3N4. Next, we report on the correlation between gate leakage current and the drain current and dedicate this behavior to the Schottky barrier and to surface related charging effects. A model with the surface related charging effects on the 2DEG and the barrier height is discussed. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Effect of 1,1,-dibenzyl-4,4,-bipyridyl dichloride (DBD) on charge-conduction process and photovoltaic response of a polypyrrole (PPy) thin-film device

    S Roy
    Abstract The present communication deals with analysing the effect of 1,1,-dibenzyl-4,4,-bipyridyl dichloride (DBD) substitution at the N -position of 2,5-polypyrrole (PPy), on electrical, impedance and photovoltaic properties. The thin-film device was fabricated by sandwiching DBD-substituted PPy between indium tin oxide (ITO) and aluminium (Al) electrodes. The formation of a Schottky barrier with Al and ohmic contact with ITO are explained in terms of p-type semiconducting behaviour of DBD-substituted PPy. In the low-voltage region, Ohm's law is followed, while in the high-voltage region, a space-charge-limited conduction (SCLC) controlled by the exponential-trap distribution was observed. DBD substitution causes shifting of the Fermi level towards the valence-band edge and an increase in charge-carrier mobility. A remarkable change in dark electrical conductivity of the order of five has been observed in DBD-substituted PPy. The electrical and impedance measurements of an ITO/PPy:DBD/Al device confirms the formation of a Schottky barrier at the DBD-substituted PPy/Al interface. Additionally, it can be modelled by a simple equivalent circuit of two resistance,capacitance (RC) elements in series representing the bulk and a junction-region. At low frequency, the device capacitance follows a pronounced voltage dependence. From a detailed analysis of the J,V and C,V characteristics, the ionized acceptor concentration (Na), width of depletion layer (W) and potential barrier height (,b) have been evaluated. We observed a significant enhancement in photocurrent on DBD substitution. The increase in photocurrent is explained by the efficient charge separation induced by the intermolecular transfer of photo-excited electrons from PPy to DBD. The substitution also causes a reduction in the trapping centres in the material. 2002 Society of Chemical Industry [source]

    Spatially Resolved Potential Distribution in Carbon Nanotube Cross-Junction Devices

    ADVANCED MATERIALS, Issue 25-26 2009
    Eduardo J. H. Lee
    Crossed-nanotube junctions, the basic constituents of carbon nanotube networks, are investigated by scanning photocurrent microscopy. The location of the predominant electrostatic potential drop, at the electrical contacts or at the junction, is found to be highly dependent on the transport regime. Also, whereas Schottky barriers are formed at M-S (metal,semiconductor) nanotube crossings, isotype heterojunctions are formed at S-S ones (figure). [source]

    Fluctuation model for a rough metal/semiconductor interface

    N. L. Dmitruk
    Abstract The fluctuation model with Gaussian-type of barrier heights distribution that was recently applied successfully to explain the dark current,voltage characteristics of Au/GaAs barrier structure with microrelief interface, in this paper is extended to photoelectric characteristics. In addition to the change of the Richardson constant and the apparent temperature coefficient of barrier height we predict the decrease of the open-circuit voltage of photodetectors or solar cells. The theoretical predictions have been verified experimentally on the Au/GaAs Schottky barriers with dendrite-like or quasigrating interface prepared by wet anisotropic etching. [source]