Showing papers on "Schottky diode published in 2006"
TL;DR: The metal source/drain (S/D) Schottky-barrier (SB) MOSFET technology as mentioned in this paper offers several benefits that enable scaling to sub-30-nm gate lengths.
Abstract: In this paper, the metal source/drain (S/D) Schottky-barrier (SB) MOSFET technology is reviewed. The technology offers several benefits that enable scaling to sub-30-nm gate lengths including extremely low parasitic S/D resistance (1% of the total device resistance), atomically abrupt junctions that enable the physical scaling of the device to sub-10-nm gate lengths, superior control of OFF-state leakage current due to the intrinsic Schottky potential barrier, and elimination of parasitic bipolar action. These and other benefits accrue using a low-thermal-budget CMOS manufacturing process requiring two fewer masks than conventional bulk CMOS. The SB-CMOS manufacturing process enables integration of critical new materials such as high-k gate insulators and strained silicon substrates. SB MOSFET technology state of the art is also reviewed, and shown to be focused on barrier-height-lowering techniques that use interfacial layers between the metal S/Ds and the channel region. SB-PMOS devices tend to have superior performance compared to NMOS, but NMOS performance has recently improved by using ytterbium silicide or by using hybrid structures that incorporate interfacial layers to lower the SB height.
486 citations
TL;DR: Rectifying diodes of single nanobelt/nanowire-based devices have been fabricated by aligning single ZnO nanobelts/ nanowires across paired Au electrodes using dielectrophoresis to form the Schottky diode.
Abstract: Rectifying diodes of single nanobelt/nanowire-based devices have been fabricated by aligning single ZnO nanobelts/nanowires across paired Au electrodes using dielectrophoresis. A current of 0.5 μA at 1.5 V forward bias has been received, and the diode can bear an applied voltage of up to 10 V. The ideality factor of the diode is ∼3, and the on-to-off current ratio is as high as 2000. The detailed IV characteristics of the Schottky diodes have been investigated at low temperatures. The formation of the Schottky diodes is suggested due to the asymmetric contacts formed in the dielectrophoresis aligning process.
355 citations
TL;DR: In this article, the authors proposed that the key carrier transport process is emission of electrons from a trap state near the metal-semiconductor interface into a continuum of states associated with each conductive dislocation.
Abstract: Temperature-dependent current-voltage measurements combined with conductive atomic force microscopy and analytical modeling have been used to assess possible mechanisms of reverse-bias leakage current flow in Schottky diodes fabricated from GaN and Al0.25Ga0.75N∕GaN structures grown by molecular-beam epitaxy. Below 150K, leakage current is nearly independent of temperature, indicating that conduction is dominated by tunneling transport. At higher temperatures, leakage current in both GaN and Al0.25Ga0.75N∕GaN diode structures is well described by a Frenkel-Poole emission model. Based on the inferred emission barrier heights and the observation that room-temperature leakage current is dominated by the presence of highly conductive dislocations, it is suggested that the key carrier transport process is emission of electrons from a trap state near the metal-semiconductor interface into a continuum of states associated with each conductive dislocation. In this model for leakage current flow, the emission barr...
312 citations
TL;DR: In this article, the authors modeled the transport in the nanowire as in a metal-semiconductor-metal structure involving two Schottky barriers and a resistor in between these barriers.
Abstract: Electrical transport measurements were conducted on semiconducting nanowires and three distinct current-voltage (I-V) characteristics were observed, i.e., almost symmetric, almost rectifying, and almost linear. These I-V characteristics were modeled by treating the transport in the nanowire as in a metal-semiconductor-metal structure involving two Schottky barriers and a resistor in between these barriers, and the transport is shown to be dominated by the reverse-biased Schottky barrier under low bias and by the semiconducting nanowire at large bias. In contrast to the conventional Schottky diode, the reverse current in the nano-Schottky barrier structure is not negligible and the current is largely tunneling rather than thermionic. Experimental I-V curves are reproduced very well using our model, and a method for extracting nanowire resistance, electron density, and mobility is proposed and applied to ZnO, CdS, and Bi2S3 nanowires.
276 citations
TL;DR: Schottky barrier field effect transistors based on individual catalytically-grown and undoped Si-nanowires (NW) have been fabricated and characterized with respect to their gate lengths, and the transistors displayed p-type behaviour, sustained current densities, and on/off current ratios.
Abstract: Schottky barrier field effect transistors based on individual catalytically-grown and undoped Si-nanowires (NW) have been fabricated and characterized with respect to their gate lengths. The gate length was shortened by the axial, self-aligned formation of nickel-silicide source and drain segments along the NW. The transistors with 10−30 nm NW diameters displayed p-type behaviour, sustained current densities of up to 0.5 MA/cm2, and exhibited on/off current ratios of up to 107. The on-currents were limited and kept constant by the Schottky contacts for gate lengths below 1 μm, and decreased exponentially for gate lengths exceeding 1 μm.
244 citations
TL;DR: The performance and reliability issues unique to SiC discussed here include: (a) MOS channel conductance/gate dielectric reliability trade-off due to lower channel mobility as well as SiC–SiO2 barrier lowering due to interface traps; (b) reduction in breakdown field and increased leakageCurrent due to material defects; and (c) increased leakage current in SiC Schottky devices at high temperatures.
230 citations
TL;DR: It is shown that the accumulation of spin-polarized electrons at a forward-biased Schottky tunnel barrier between Fe and -GaAs can be detected electrically and the dependence of the electrical accumulation signal on magnetic field, bias current, and temperature is in good agreement with the predictions of a drift-diffusion model for spin- polarized transport.
Abstract: We show that the accumulation of spin-polarized electrons at a forward-biased Schottky tunnel barrier between Fe and -GaAs can be detected electrically. The spin accumulation leads to an additional voltage drop across the barrier that is suppressed by a small transverse magnetic field, which depolarizes the spins in the semiconductor. The dependence of the electrical accumulation signal on magnetic field, bias current, and temperature is in good agreement with the predictions of a drift-diffusion model for spin-polarized transport.
192 citations
TL;DR: In this paper, the temperature dependence of barrier height of high quality Pd Schottky contacts on (0001)-oriented ZnO thin films by temperature-dependent current-voltage and capacitance voltage measurements was investigated.
Abstract: We have investigated the temperature dependence of the barrier height of high-quality Pd Schottky contacts on (0001)-oriented ZnO thin films by temperature-dependent current-voltage and capacitance-voltage (CV) measurements. The films have been grown by pulsed-laser deposition. The effective Schottky barrier height ΦB,eff deduced from the current-voltage measurements was evaluated by considering a Gaussian barrier height distribution with a standard deviation σ around a mean barrier height ΦB,m. We determined ΦB,m=(1.16±0.04)eV which agrees well with the value of 1.14eV determined by CV measurements. The standard deviation is determined to be (134±10)meV.
164 citations
TL;DR: In this article, Pd, Pt, Au, and Ag Schottky diodes with low ideality factors were fabricated on the Zn-polar (0001) and Opolar faces of bulk, single crystal ZnO wafers.
Abstract: Planar Pd, Pt, Au, and Ag Schottky diodes with low ideality factors were fabricated on the Zn-polar (0001) and O-polar (0001¯) faces of bulk, single crystal ZnO wafers. The diodes were characterized by current-voltage and capacitance-voltage measurements. A polarity effect was observed for Pt and Pd diodes with higher quality barriers achieved on the O-polar face. No significant polarity effect was observed for Au or Ag diodes. The highest barriers were achieved with Ag as the Schottky metal with barrier heights varying between 0.77 and 1.02eV. This is possibly due to varying degrees of oxidation of the Ag contacts.
152 citations
TL;DR: By imposing an ultrathin insulator between low-work function metals and silicon, the Schottky barrier of the junction can be substantially reduced, decreasing junction resistance as discussed by the authors, and this approach, low-Schottky-barrier metal source/drain transistors with Mg and Yb as S/D metals are demonstrated.
Abstract: By imposing an ultrathin insulator between low-work function metals and silicon, the Schottky barrier of the junction can be substantially reduced, decreasing junction resistance. With this approach, low-Schottky-barrier metal source/drain (S/D) transistors with Mg and Yb as S/D metals are demonstrated.
146 citations
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TL;DR: In this article, a review of Ohmic and Schottky contacts to n-and p-type ZnO is given, with Ohmic contacts having resistivity in the range 10 −6 ǫ cm 2 even for unnannealed contacts on strongly n-type layers.
TL;DR: In this article, fine control of p-, n-, and ambipolar-type field effect transistor (FET) operations is successfully demonstrated in prototypical single-crystal organic FETs with use of chemically tunable nature of Fermi energy in tetrathiafulvalene-tetracyanoguinodimethane-based organic metal electrodes.
Abstract: Fine control of p-, n-, and ambipolar-type field-effect transistor (FET) operations is successfully demonstrated in prototypical single-crystal organic FETs with use of chemically tunable nature of Fermi energy in tetrathiafulvalene-tetracyanoguinodimethane-based organic metal electrodes. Carrier-type preference and rectifying nature in the organic-organic contacts are revealed in terms of the FET operations as well as of the all-organic Schottky diode characteristics.
TL;DR: In this article, the p-type behavior of Sb-doped ZnO was studied by carrying out I-V and capacitance-voltage (C-V) measurements.
Abstract: Antimony (Sb) doping was used to realize p-type ZnO films on n-Si (100) substrates by molecular beam epitaxy. These samples were fabricated into p-n heterojunction diodes. p-type behavior of Sb-doped ZnO was studied by carrying out I-V and capacitance-voltage (C-V) measurements. I-V curves showed rectifying behavior similar to a p-type Schottky diode with a turn-on voltage around 2.4V, which is consistent with the Schottky barrier of about 2.2V obtained from C-V characterization. Good photoresponse in the UV region was obtained, which further proved that Sb doping could be used to fabricate p-type ZnO for photodetector and other optoelectronic applications.
TL;DR: In this article, single-walled carbon nanotube (CNT) gas sensors were fabricated by dielectrophoresis onto microelectrodes made of Cr, Pd or Al.
Abstract: Single-walled carbon nanotube (CNT) gas sensors were fabricated by dielectrophoresis onto microelectrodes made of Cr, Pd or Al. The Al/CNT sensor response to NO2 (nitrogen dioxide) gas was characterized by fast and large resistance increase at the moment of NO2 exposure, whereas the resistance of the other metal/CNT sensors monotonously decreased. It was suggested that the adsorbed NO2 molecules might alter the Schottky barrier at the Al/CNT interface as well as the positive hole density in the p-type semiconducting CNT. The Al/CNT sensor response could be interpreted as a superposition of the Schottky contact resistance and the CNT resistance, which were differently influenced by the NO2 adsorption and contributed to the overall sensor response. The Schottky response of the Al/CNT sensor was approximately one order of magnitude faster than the CNT response obtained using the other metal electrodes. © 2005 Elsevier B.V. All rights reserved.
TL;DR: In this paper, the authors reviewed recent progress in SiC technology for power electronic devices beyond Si and described historical aspects of SiC development, such as bulk crystal growth, epitaxial growth, and device processes for new generation SiC power devices are briefly explained.
TL;DR: In this article, the I-V characteristics of metal-insulator-semiconductor Al/SiO"2/p-Si (MIS) Schottky diodes were measured at room temperature (300K) and capacitance-voltage-frequency (C-V-f) characteristics were investigated by considering the interface states at frequency range 100kHz to 1MHz.
TL;DR: In this article, the impact of threading dislocation density on Ni∕n-GaN Schottky barrier diode characteristics was investigated using forward biased current-voltage-temperature (I-V-T) and internal photoemission (IPE) measurements.
Abstract: The impact of threading dislocation density on Ni∕n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature (I-V-T) and internal photoemission (IPE) measurements. Nominally, identical metal-organic chemical vapor deposition grown GaN layers were grown on two types of GaN templates on sapphire substrates to controllably vary threading dislocation density (TDD) from 3×107to7×108cm−2. I-V-T measurements revealed thermionic emission to be the dominant transport mechanism with ideality factors near 1.01 at room temperature for both sample types. The Schottky barrier heights showed a similar invariance with TDD, with measured values of 1.12–1.13eV obtained from fitting the I-V-T results to a thermionic emission-diffusion model. The I-V-T results were verified by IPE measurements made on the same diodes, confirming that the Ni∕n-GaN barrier heights do not show a measurable TDD dependence for the TDD range measured here. In apparent contrast to this result is th...
TL;DR: In this article, the authors compared the performance of two different organic diode structures, a vertical diode and an organic field effect transistor (OTFT) with shorted drain-gate contact, regarding their application in a rectifying circuit.
Abstract: In this article, we compare the direct current (dc) and high-frequency performance of two different organic diode structures, a vertical diode and an organic field effect transistor (OTFT) with shorted drain-gate contact, regarding their application in a rectifying circuit. For this purpose, we fabricated both diode structures using the organic semiconductor pentacene. dc measurements were performed showing a space-charge-limited current mobility of more than 0.1cm2∕Vs for the vertical diode and a field effect mobility of 0.8cm2∕Vs for the OTFT with shorted source-drain. High-frequency measurements of those diode structures in a rectifier configuration show that both types of diodes are able to follow the base-carrier frequency of 13.56MHz which is essential for viable radio-frequency-identification (rf-ID) tags. Based on those results we evaluate the performance limits and advantages of each diode configuration regarding their application in an organic rf-ID tag.
01 Dec 2006
TL;DR: In this article, a DS-Schottky S/D CMOS-FinFET with dopant-segregated Schottky source/drain was demonstrated.
Abstract: High-performance CMOS-FinFET with dopant-segregated Schottky source/drain (DS-Schottky S/D) technology has been demonstrated. Thanks to the low parasitic resistance in DS-Schottky S/D, high drive current of 960 muA/mum was achieved for nFET with Lg = 15 nm and Wfin =15 nm at Vd= 1.0 V and Ioff= 100 nA/mum. Furthermore, the propagation delay time has been successfully improved down to less than 5 ps in the ring oscillator with DS-Schottky S/D CMOS-FinFET with 15 nm gate length
TL;DR: In this paper, a nonpolymeric organic compound rhodamine-101 (Rh101) film has been formed by means of the evaporation process and the Sn/rhodamine101/Si contacts have been fabricated.
Abstract: The nonpolymeric organic compound rhodamine-101 (Rh101) film on a n-type Si or p-type Si substrate has been formed by means of the evaporation process and the Sn/rhodamine-101/Si contacts have been fabricated. The Sn∕Rh101∕n-Si and Sn∕Rh101∕p-Si contacts have rectifying contact behavior with the barrier height (BH) values of 0.714 and 0.827eV, and with ideality factor values of 2.720 and 2.783 obtained from their forward bias current-voltage (I-V) characteristics at room temperature, respectively. It has been seen that the BH value of 0.827eV obtained for the Sn∕Rh101∕p-Si contact is significantly larger than BH values of the conventional Sn∕p-Si Schottky diodes and metal/interfacial layer/Si contacts. Thus, modification of the interfacial potential barrier for metal/Si diodes has been achieved using a thin interlayer of the Rh101 organic semiconductor; this has been ascribed to the fact that the Rh101 interlayer increases the effective barrier height by influencing the space charge region of Si.
TL;DR: The proposed converter topology has a favorable voltage-clamped effect and superior conversion efficiency and the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage-drift problem of power source under the variation of loads.
Abstract: This paper investigates a high-efficiency clamped-voltage dc-dc converter with reduced reverse-recovery current and switch-voltage stress. In the circuit topology, it is designed by way of the combination of inductor and transformer to increase the corresponding voltage gain. Moreover, one additional inductor provides the reverse-current path of the transformer to enhance the utility rate of magnetic core. In addition, the voltage-clamped technology is used to reduce the switch-voltage stress so that it can select the Schottky diode in the output terminal for alleviating the reverse-recovery current and decreasing the switching and conduction losses. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage-drift problem of power source under the variation of loads. Thus, the proposed converter topology has a favorable voltage-clamped effect and superior conversion efficiency. Some experimental results via an example of a proton-exchange-membrane fuel cell (PEMFC) power source with a 250-W nominal rating are given to demonstrate the effectiveness of the proposed power-conversion strategy.
Patent•
26 Jan 2006
TL;DR: In this paper, a MESFET-based boost converter includes an N-channel MES-FET connected to a node Vx and an inductor connected to Vx to a battery or other power source.
Abstract: A MESFET based boost converter includes an N-channel MESFET connected to a node Vx. An inductor connects the node Vx to a battery or other power source. The node Vx is also connected to an output node via a Schottky diode or a second MESFET or both. A control circuit drives the MESFET (and the second MESFET) so that the inductor is alternately connected to ground and to the output node. The maximum voltage impressed across the low side MESFET is optionally clamped by a Zener diode. In some implementations, the MESFET is connected in series with a MOSFET. The MOSFET is switched off during sleep or standby modes to minimize leakage current through the MESFET. The MOSFET is therefore switched at a low frequency compared to the MESFET and does not contribute significantly to switching losses in the converter. In other implementations, more than one MESFET is connected in series with a MOSFET, the MOSFETs being switched off during periods of inactivity to suppress leakage currents.
Patent•
04 Apr 2006TL;DR: In this paper, a monolithically integrated field effect transistor and Schottky diode includes gate trenches extending into a semiconductor region, where a conductor layer fills the contact opening to electrically contact.
Abstract: A monolithically integrated field effect transistor and Schottky diode includes gate trenches extending into a semiconductor region. Source regions having a substantially triangular shape clank each side of the gate trenches. A contact opening extends into the semiconductor regions between adjacent gate trenches. A conductor layer fills the contact opening to electrically contact: (a) the source regions along at leaset a portion of a slanted sidewall of each source region, and (b) the semiconductor region along a bottom portion of the contact opening, wherein the conductor layer forms a Schottky contact with the semiconductor region.
TL;DR: In this paper, two models of electron tunneling from metal to a semiconductor via traps are proposed, one called generalized thermionic trap-assisted tunneling (GTTT) and the other one called thermionic trapped-assisted tunnelling (TTT).
Abstract: We propose two models of electron tunneling from metal to a semiconductor via traps. In addition to the electrons below the metal Fermi level, the models also include the thermally activated electrons above the Fermi level. The first model is called generalized thermionic trap-assisted tunneling (GTTT), which considers tunneling through both triangular and trapezoidal barriers present in metal insulator semiconductor (MIS) structures. The second model is called thermionic trap-assisted tunneling (TTT), which considers tunneling through triangular barriers present in modern Schottky junctions. The GTTT model is shown to predict the low field leakage currents in MIS structures with nitrided oxide as insulator, and the TTT model is shown to predict the reverse gate leakage in AlGaN∕GaN high electron mobility transistors.
TL;DR: Carbon nanotube Schottky diodes were fabricated using asymmetric metal-nanotube contacts as discussed by the authors, which were prepared from semiconducting single-walled carbon nanotubes contacted by one Al or Ti electrode and one Au electrode.
Abstract: Carbon nanotube Schottky diodes were fabricated using asymmetric metal-nanotube contacts. These devices were prepared from semiconducting single-walled carbon nanotubes contacted by one Al or Ti electrode and one Au electrode. Nanotubes formed a low resistance contact with the Au electrode and a Schottky contact with the Al or Ti electrode. Electronic transport through the Schottky barriers was determined by the competition between tunneling and thermionic emission, which could be tuned by a back gate voltage.
TL;DR: In this paper, an ultraviolet photodiode employing a single ZnO tetrapod nanocrystal is reported, which is prepared by depositing W and Pt electrodes to form Ohmic and Schottky contacts, respectively.
Abstract: The fabrication of an ultraviolet photodiode employing a single ZnO tetrapod nanocrystal is reported. This diode structure is prepared by depositing W and Pt electrodes to form Ohmic and Schottky contacts, respectively. Dark current-voltage measurements show rectifying behavior. The properties of the metal-semiconductor interface are studied with above and below band gap illumination. It is found that with increasing UV excitation the device converts from a rectifying to an Ohmic behavior. This effect is attributed to a flattening of the energy bands due to the migration of photogenerated carriers within the space charge region at the metal-semiconductor interface.
TL;DR: In this article, the current and capacitance properties of Au/n-GaAs contacts have been measured in the temperature range of 80?300 K. An abnormal decrease in the experimental BH?b and an increase in the ideality factor n with a decrease in temperature have been observed.
Abstract: The current?voltage (I?V) and capacitance?voltage (C?V) characteristics of Au/n-GaAs contacts have been measured in the temperature range of 80?300 K. An abnormal decrease in the experimental BH ?b and an increase in the ideality factor n with a decrease in temperature have been observed. This behaviour has been attributed to the barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the metal?semiconductor interface. The temperature-dependent I?V characteristics of the Au/n-GaAs contact have shown a double Gaussian distribution giving mean barrier heights of 0.967 and 0.710 eV and standard deviations of 0.105 and 0.071 V, respectively. A modified ln(I0/T2) ? q2?2s/2k2T2 versus 1/T plot for the two temperature regions then gives and A* as 0.976 and 0.703 eV, and 13.376 and 8.110 A cm?2 K?2, respectively. Furthermore, a value of ?0.674 meV K?1 for the temperature coefficient has been obtained, and the value of ?0.674 meV K?1 for the Au/n-GaAs Schottky diode is in close agreement with those in the literature.
TL;DR: The role of Pr doping on double Schottky barrier formations at ZnO single grain boundaries was investigated by the combination of current-voltage measurements, atomic-resolution Z-contrast scanning transmission electron microscopy, and first-principles calculations.
Abstract: The role of Pr doping on double Schottky barrier formations at ZnO single grain boundaries was investigated by the combination of current-voltage measurements, atomic-resolution $Z$-contrast scanning transmission electron microscopy, and first-principles calculations. Although Pr segregated to the specific atomic site along the boundaries, it was found not to be the direct cause of nonlinear current-voltage properties. Instead, under appropriate annealing conditions, Pr enhances formations of acceptor-type native defects that are essential for the creation of double Schottky barriers in ZnO.
TL;DR: In this paper, the annealing characteristics of Ni/crystal-Ge stacked structures were examined and it was shown that NiGe∕n-Ge Schottky contacts (ϕBn=051eV, n=1) with flat interfaces and low reverse leakage current (2 −5)×10−2A∕cm2) could be obtained by choosing an appropriate anneeling temperature (200 −300°C)
Abstract: Poly-Ge thin-film transistors (TFTs) with Schottky source/drain (S/D) contacts were fabricated on glass by low-temperature (<500°C) processing First, the annealing characteristics of Ni/crystal-Ge stacked structures were examined The results indicated that NiGe∕n-Ge Schottky contacts (ϕBn=051eV, n=1) with flat interfaces and low reverse leakage current [(2–5)×10−2A∕cm2] could be obtained by choosing an appropriate annealing temperature (200–300°C) Based on this result, p-channel TFTs were fabricated with poly-Ge formed on glass by solid-phase crystallization at 500°C TFTs showed relatively high hole mobility (about 140cm2∕Vs) with very low S/D parasitic resistance and no kink effect The potential capability of the proposed devices for high-performance TFTs was demonstrated