Showing papers on "Schottky diode published in 1984"

High voltage semiconductor device

Abstract: A field effect transistor, a bipolar transistor, a PIN diode, a Schottky rectifier or other high voltage semiconductor device comprise a semiconductor body having a depletion layer formed throughout a portion in at least a high voltage mode of operation of the device, such as, by reverse biasing a rectifying junction. The known use of a single high-resistivity body portion of one conductivity type to carry both the high voltage and to conduct current results in a series resistivity increasing approximately in proportion with the square of the breakdown voltage. This square-law relationship is avoided by the present invention in which a depleted body portion comprising an interleaved structure of first and second regions of alternating conductivity types carries the high voltage which occurs across the depleted body portion. The thickness and doping concentration of each of these first and second regions are such that when depleted the space charge per unit area formed in each of these regions is balanced at least to the extent that an electric field resulting from any imbalance is less than the critical field strength at which avalanche breakdown would occur in the body portion. The first regions in at least one mode of operation of the device provide electrically parallel current paths extending through the body portion.

Schottky-Barrier Formation at Single-Crystal Metal-Semiconductor Interfaces

Abstract: Electrical behaviors at two single-crystal metal-semiconductor interfaces are studied. Schottky-barrier heights of NiSi2layers grown under ultrahigh-vacuum conditions on n- type Si(111) are found to be 0.65 and 0.79 eV for type-Aand type-Bepitaxial systems, respectively. These results are compared with the proposed theoretical models of Schottky barriers.

The pinch rectifier: A low-forward-drop high-speed power diode

Abstract: A new concept for reducing the forward voltage drop of Schottky rectifiers without incurring excessive reverse leakage currents is introduced. In this concept, a junction grid is incorporated beneath the Schottky barrier to pinch off current flow during reverse blocking. Experimental results that demonstrate the capability to reduce the forward drop from 0.6 to 0.4 V without incurring an increase in leakage current are presented.

An improved forward I-V method for nonideal Schottky diodes with high series resistance

Abstract: Two methods are described to obtain the value of the series resistance (R) of a Schottky diode from its forward I-V characteristic. The value of R is then used to plot the curve ln ( I ) versus V_{D} (= V - IR) which becomes a straight line even if ln (I) versus V does not. The ideality factor n and the Schottky-barrier height \Phi_{B0} of the diode then follow from the standard procedure. The main advantages of the methods are: 1) a linear regression can be used to calculate the value of R , 2) many data points are used over the whole data range which raises the accuracy of the results, and 3) the validity of constant R assumption can be checked by the linearity of the ln (I) versus V D curve. The methods are illustrated on the experimental data of a real diode.

Metal‐semiconductor field‐effect transistors fabricated in GaAs layers grown directly on Si substrates by molecular beam epitaxy

Abstract: Device‐quality GaAs layers have been grown directly on Si(100) substrates by molecular beam epitaxy. Metal‐semiconductor field‐effect transistors have been fabricated in these layers with transconductance as high as 85 mS/mm and leakage current as low as 1 μA at Vgs =−3 V for gate dimensions of 2.0 μm×200 μm.

Visible/infrared imaging device with stacked cell structure

Abstract: A solid-state image sensing device such as an IT-CCD has first and second photosensing sections which are stacked so that they separately sense visible and infrared image light components contained in input light. The visible image light component contained in image light irradiated through a transparent layer is absorbed by a silicon amorphous layer, thereby sensing a visible image. The remaining light component is transmitted through an insulative layer, and is irradiated into an n+ diffusion layer which consists of a Schottky diode and serves as the second photosensing section. The infrared image light component is absorbed in the Schottky diode, thereby sensing the infrared light image.

Current‐voltage characteristic of Ti‐pSi metal‐oxide‐semiconductor diodes

Abstract: The electrical characteristics of Ti‐pSi metal‐oxide‐semiconductor diodes have been studied as a function of temperature and of applied voltage, using conventional Schottky barrier capacitance‐voltage (C‐V) and current‐voltage (I‐V) measurements. The results show a strong deviation from those expected from thermionic emission and from the minority carrier injection theory for the current mechanism. Unlike other authors who proposed a multistep recombination‐tunneling mechanism, we have stressed that a model based on the inhomogeneity of the barrier height over the diode area predicts a temperature and voltage behavior of the I‐V characteristic similar to the recombination‐tunneling mechanism. The concept of inhomogeneity proposed by former authors is supported by Auger depth concentration profiles which show an intermixed region of Ti and Si. It is observed that the equilibrium semiconductor band bending exhibits a stronger temperature dependence than expected from the variation of the semiconductor Fermi level.

Topics in the optimization of millimeter-wave mixers

Abstract: A user oriented computer program for the analysis of single-ended Schottky diode mixers is described. The program is used to compute the performance of a 140 to 220 GHz mixer and excellent agreement with measurements at 150 and 180 GHz is obtained. A sensitivity analysis indicates the importance of various diode and mount characteristics on the mixer performance. A computer program for the analysis of varactor diode multipliers is described. The diode operates in either the reverse biased varactor mode or with substantial forward current flow where the conversion mechanism is predominantly resistive. A description and analysis of a new H-plane rectangular waveguide transformer is reported. The transformer is made quickly and easily in split-block waveguide using a standard slitting saw. It is particularly suited for use in the millimeter-wave band, replacing conventional electroformed stepped transformers. A theoretical analysis of the transformer is given and good agreement is obtained with measurements made at X-band.

Effect of antimony ion implantation on Al‐silicon Schottky diode characteristics

Abstract: Shallow (≲100 A) antimony ion implantation on n‐type silicon is shown to reduce the effective barrier height on Al Schottky diodes formed on the implanted surface irrespective of postimplant annealing. The mechanisms of barrier reduction are quite different in the two cases. In the postimplant annealed case, the antimony is activated resulting in barrier height reduction due to the surface N+ dopant charge, while in the unannealed case, lattice damage causes barrier height reduction as observed earlier for ion etched silicon surfaces.

Process for producing CMOS structures with Schottky bipolar transistors

Abstract: A process is disclosed for making CMOS transistors in combination with self-aligned fully oxide isolated Schottky clamped bipolar transistors.

Monolithic integration of a metal—semiconductor—metal photodiode and a GaAs preamplifier

Abstract: A metal-semiconductor-metal (MSM) photodiode and a preamplifier have been monolithically integrated on a GaAs substrate by a very simple fabrication process. Measurements have shown that the constituent MSM photodiode has a sensitivity of 2.2 A/W and a -3-dB cutoff frequency of as high as 1 GHz. The present photodiode has been found to realize an extremely high photosensitivity of the monolithically integrated circuit, 26 mV/µW.

Schottky barrier heights of single crystal silicides on Si(111)

Abstract: Capacitance–voltage and current–voltage characteristics at single crystal silicide–silicon interfaces are studied. Schottky barrier heights are determined for epitaxial NiSi2 and CoSi2 layers grown under ultrahigh vacuum conditions on Si(111). These results demonstrate that there is an influence of interface structure on Schottky barrier height. This dependence suggests a reassessment of many previous interpretations or models of Schottky barriers. It also shows that experimentally measured barrier heights of metal–semiconductor systems with inhomogeneous interface structure are likely to be the averages from those associated with different regions of the interface. Homogeneous metal–semiconductor interfaces are therefore the simplest and most desirable systems for the study of Schottky barrier mechanisms. In particular, the present epitaxial silicide–silicon interfaces represent ideal candidates for detailed theoretical investigations based on experimentally obtained atomic structures.

Gap states density in a-Si:H deduced from subgap optical absorption measurement on Schottky solar cells

Abstract: The density of states in amorphous hydrogenated silicon is obtained by deconvolution of the optical absorption coefficient a in the full sub band-gap region. The spectral dependence of the optical absorption coefficient is measured by a constant photocurrent method (CPM) on forward-biased Schottky diodes. The spectral dependence of reflection on the semitransparent Pt electrode is determined. All assumptions used in the deconvolution of a are discussed. The difference in measured value of a (by CPM) in the region below approximately 0.9 eV compared to the measurement of α by photothermal deflection spectroscopy (PDS) is explained by an absorption process seen in PDS and not seen in CPM. This absorption is supposed to be a transition from a deep localized state to a deep localized gap state (two different charge states of the same defect). [Russian Text Ignored]

Complete electrical characterization of recombination properties of titanium in silicon

Abstract: Using only purely electrical measurements based on the capacitance transient techniques, for the first time all the four majority and minority carrier capture rates in zero field as well as the two emission rates of the two Ti deep levels have been directly obtained on a single n+/p diode. The data are in good agreement with our results from other n+/p and n‐Si and p‐Si Schottky barriers and give a reliable picture of the recombination properties of Ti impurity in silicon. The capture rate and level concentration data support the double donor model. The first donor level is found located at EC−271 meV and has electron capture cross section of (2.57±0.17)×10−14 exp[(3.9±0.6) meV/kT] cm2 and hole capture cross section of 1.35×10−15 cm2. The second donor level is located at EV+255 meV and has electron capture cross section of (1.30±0.05)×10−14 (300/T) cm2 and hole capture cross section of (1.09±0.14)×10−16 exp[−(27.0±1.2) meV/kT] cm2.

Interface effects in titanium and hafnium Schottky barriers on silicon

Abstract: The effect of Si surface contaminants present prior to metal deposition, and that of post‐metalization anneals has been investigated for Ti and Hf Schottky barriers on Si. These diodes have been prepared in ultrahigh vacuum, characterized with Auger spectroscopy and measured in situ using internal photoemission, and ex situ using current‐voltage measurements. Although barriers to p‐type Si as high as 0.9 eV have been reported in the literature for these metals, barriers of 0.72 eV were the highest observed in this investigation, for surfaces contaminated with significant amounts of oxygen.

Physics of Schottky Barrier Junctions

Abstract: A rectifying metal-semiconductor contact is known as a Schottky barrier after W. Schottky, who first proposed a model for barrier formation. Our knowledge of metal-semiconductor diodes is more than a century old. F. Braun,(1) in 1874, reported the rectifying nature of metallic contacts on copper, iron, and lead sulfide crystals. Although numerous experimental and theoretical studies have been carried out since then, our understanding of the metalsemiconductor junctions is still far from complete. This is perhaps due to the fact that their performance is highly process dependent.

A diffusion problem in semiconductor technology

Abstract: This paper deals with a mathematical model of a SEM-EBIC experiment devised to measure the diffusion length of semiconductor materials. In the model the semiconductor material occupies a half-space, of which the plane bounding surface is partly covered by a semi-infinite current-collecting junction, the Schottky diode. A scanning electron microscope (SEM) is used to inject minority carriers into the material. It is assumed that injection occurs at a single point only. The injected minority carriers diffuse through the material and recombine in the bulk at a rate proportional to their local concentration. Recombination also occurs at the free surface of the material, not covered by the junction, where its rate is determined by the surface recombination velocity v. The mathematical model gives rise to a mixed-boundary-value problem for the diffusion equation, which is solved by means of the Wiener-Hopf technique. An analytical expression is derived for the measurable electron-beam-induced current (EBIC) caused by the minority carriers reaching the junction. The solution obtained is valid for all values of v, and special attention is given to the limiting cases v=∞ and v=0. Asymptotic expansions of the induced current, which are usable when the injection point is more than a few diffusion lengths away from the edge of the junction, are derived as well.

Characteristics of WN/GaAs Schottky Contacts Formed by Reactive RF Sputtering

Abstract: WN film formation by a reactive rf sputtering and WN/GaAs Schottky contact characteristics were investigated with the intent of forming a gate for self-aligned MESFETs. WN/GaAs contacts show good Schottky diode characteristics even after high temperature annealing. Both the ideality factor n and flat band barrier height B0C of contacts showed nearly constant values of about 1.1 and 1.15 eV, respectively, for annealing at about 800°C and for annealing longer than 20 min.

A Broad-Band, Ultra-Low-Noise Schottky Diode Receiver from 80 to 115 GHz Diode

Abstract: A cryogenic 3-mm receiver has been developed which fully utilizes the low-noise potential of Schottky diodes by approaching the shot-noise limit within 10 percent. With a broad-band mixer design which properly terminates the input sidebands and reactively terminates the second harmonic of the local oscillator and its sidebands, the double sideband (DSB) mixer noise temperature is 35 K in the best case. This design has given an average DSB receiver noise temperature of 75 K over the 80 to 115-GHz band with a best noise temperature of 62 K.

Effect of argon ion implantation dose on silicon Schottky barrier characteristics

Abstract: The electrical characteristics of Schottky diodes fabricated on silicon surfaces subject to low‐energy (10 keV) argon ion implantation have been studied as a function of Ar+ ion dose. Significant changes in electrical characteristics are seen for ion doses as low as 5×1011 cm−2, well below the amorphization threshold dose for Si. In conjunction with the ion energy threshold established earlier for Si surface damage effects (∼25 eV), these results outline fundamental limits on the effect of ion‐assisted dry etching processes on Si surface barriers.

Fabrication and characterization of GaAs Schottky barrier photodetectors for microwave fiber optic links

Abstract: High‐Speed GaAs Schottky barrier photodiodes have been fabricated and characterized. These detectors have 3‐dB bandwidths of 20 GHz and quantum efficiencies as high as 70%. The response of the detectors to light modulated at 1–18 GHz has been directly measured. Microwave modulated optical signals were obtained by using a LiNbO3 traveling wave modulator and by heterodyning two laser diodes.

Temperature compensated ttl to ecl translator

Abstract: A temperature compensated differential level shift circuit (Fig. 2). An ECL type buffered differential circuit employs a source of threshold voltage, VT (Fig. 3), which matches the temperature-dependent characteristic of the input section of the level shift circuit. In a preferred embodiment, s Schottky diode (52) is provided in the output section of a bandgap reference voltage generator (Fig. 3) which matches the temperature dependence of a Schottky diode (30) in the input section of the level shift circuit (Fig. 2). As temperature shifts, the threshold voltage will shift in a manner that tracks the temperature-produced shift in the input voltage as it passes through the Schottky diode in the input section of the level shift circuit. Matched PNP or NPN transistors (70, 72 and 71, 73 ) may also be used in the input section of the level shift circuit (Figs. 6A, 7A) and in the output section of the bandgap reference voltage generator (Figs. 6B, 7B).

Leakage Currents in Multilayer Ceramic Capacitors

Abstract: Leakage currents in new and degraded (typically at twice rated voltage, 125°C) ZSU and X7R types Of multilayer ceramic (MLC) capacitors show both ohmic and space charge limited current behavior. The near 3/2 power voltage characteristic (la V3/2) of new devices can be attributed to electron emission from electrode points. The quadratic behavior (I \alpha V2) seen for moderately degraded devices represents space charge limited emission from near planar electrodes. This emission may evolve from the point emission due to resistivity decreases that occur in the emission region as a result of ion movement. For these currents, electrons are believed to be the dominant charge carriers. Neither Schottky or Poole-Frenkel currents were identified. Thermal activation energies decrease from ~1.3 eV for new X7R devices, to zero for degraded ones, corresponding to resistivity decreases from ~ 1013 \Omega -cm to 105 \Omega -cm or less (at 125°C). Carrier concentrations and mobilities have been estimated from thermoelectric measurements on new and reduced nonelectroded X7R chips, which exhibit n-type conduction. These parameters both increase substantially with reduction, with mobility dominating the thermal activation energy. These measurements are consistent with a small polaron hopping mode for electron transport in the ceramic.

Method of making improved lateral polysilicon diode by treating plasma etched sidewalls to remove defects

Abstract: An improved lateral polysilicon diode in an integrated circuit structure is disclosed. The diode is characterized by low reverse current leakage, a breakdown voltage of at least 5 volts, and low series resistance permitting high current flow before being limited by saturation. The polysilicon diode comprises a polysilicon substrate having a first zone sufficiently doped to provide a first semiconductor type and a second zone sufficiently doped to provide a second semiconductor type whereby the junction between the two zones forms a diode. The lateral edges of the diode are treated to remove defects to thereby inhibit current leakage around the edges of the lateral diode to lower the reverse current leakage of the diode.

Schottky barrier diode with guard ring

Abstract: A guard-ring-equipped Schottky barrier diode, which can have shortened reverse recovery time and increased withstand voltage, has a Schottky barrier layer (27) formed on a semiconductor substrate (20) of a first conductivity type and a guard ring (25), which has a second conductivity type, formed on surface of the substrate (20) isolated from but surrounding the periphery of the barrier layer (27). An insulative film (23) with an opening over part of the guard ring (25) is formed over the region between the edge of the Schottky barrier layer (27) and the guard ring (25). A high-resistance layer (26) is formed on this opening and is connected with the Schottky barrier layer (27) by a metal electrode (28). The size of the area between the guard ring (25) and the end ofthe barrier layer (27) is less than the sum of the widths of the depletion layers of the guard ring (25) and the barrier layer (27) at the time when the lower voltage of either the barrier layer (27) breakdown voltage or the guard ring (25) breakdown voltage is applied.

Fluctuations in Schottky barrier heights

Abstract: A double Schottky barrier is often formed at the grain boundary in polycrystalline semiconductors. The barrier height is shown to fluctuate in value due to the random nature of the impurity positions. The magnitude of the fluctuations is 0.1 eV, and the fluctuations cause the barrier height measured by capacitance to differ from the one measured by electrical conductivity.

A Dual Six-Port Network Analyzer Using Diode Detectors

Abstract: The performance of a dual six-port network analyzer using diode detectors is described. The network analyzer operates over the 2-18-GHz band using commercially available low-barrier Schottky diodes. The paper describes the process for calibrating the diodes for deviation from square law. Measurement results are presented showing the accuracy and precision of tbe six-port network analyzer when measuring 1-port and 2-port devices. Key work attenuation measurements, automated network analyzer, impedance measurements, microwave network analyzer, network analyzer, and six-port.

Manufacture of semiconductor device

Abstract: PURPOSE:To enable arbitrary selection of the forward voltage of a Schottky barrier diode within a certain range by a method wherein a metal silicide film formed on an Si substrate is etched into a required film thickness by sputter etching. CONSTITUTION:On etching treatment of the Si substrate 7 where a Pt silicide film 4 has been formed, the film and an oxide film 2 are both removed in surface layers. The speed of etching removal of the film 2 is smaller than that of the film 4. Therefore, the effect of sputter etching can be thought only as the reduction in the thickness of the film 4. Since the amount of this removal increases in proportion to time if the high frequency power is kept constant, the thickness of the film 4 can be controlled with the sputter etching time. An electrode metal 6 and a barrier metal 5 inhibiting the reaction of the film 4 with the metal 6 are formed on the substrate, and then the Schottky barrier diode having an arbitrary forward voltage is formed.

Single and double carrier injection in A-Si:H

Abstract: The far forward current in α-Si:H Schottky diodes has been compared with the current in nin devices with identical i-layers. The former is about one order of magnitude larger and has to be described by double injection, while the latter is governed by single-carrier space-charge-limited conduction. The transient behaviour of the diodes is also different from that in nin devices and confirms the occurrence of double injection. Metastable changes in α-Si:H (the Staebler-Wronski effect) are obtained after current-soaking in pip samples, but not after current-soaking in nin samples. To explain this, a model is suggested which is based on SiSi bond weakening by hole trapping in valence band tail states.