Showing papers on "Schottky diode published in 1970"

Reverse current-voltage characteristics of metal-silicide Schottky diodes

Abstract: The soft behavior of reverse biased Schottky barrier diodes has often been difficult to interpret quantitatively. The development of metal-silicide devices with diffused guard rings has made it possible to verify experimentally an advanced theoretical model. Reverse characteristics can now be accurately predicted over wide ranges of current, voltage, barrier height and temperature. The theoretical description accounts for anisotropy of effective masses, scattering by optical phonons, and quantum mechanical reflection and tunneling at the metal-semiconductor interface. These considerations yield practical Richardson constants equal to 112 for electrons and 32 for holes in silicon. Absence of true saturation in the reverse characteristic is caused by an electric field dependence of the effective barrier height. In addition to the usual image-force correction, the barrier height is lowered by a newly recognized effect attributed to an electrostatic dipole layer at the metal-semiconductor interface. Experimental devices have been fabricated using RhSi, ZrSi2, and PtSi contacts, forming barriers in both n- and p-type silicon. The resulting structures have been found to be extremely stable and uniform; furthermore, the metal-semiconductor interface, produced by solid-solid chemical reaction, is believed to be free from intervening layers of oxide and other contaminants. When necessary to eliminate field-enhancement at the electrode periphery, diffused guard rings have been incorporated into the structures. Agreement between experimental data and theory is obtained over nearly five orders of magnitude in reverse bias and eleven orders of magnitude in reverse current density, usually with an rms deviation of less than 10 per cent.

Alternating Current Electrical Properties of Highly Doped Insulating Films

Abstract: Metal‐insulator‐metal systems are discussed in which the insulator is highly doped and in which Schottky barriers exist at the metal‐insulator interface. An equivalent circuit for the system is proposed and the ac electrical characteristics derived. It is shown that the capacitance is extremely temperature and frequency dependent. At high frequencies or low temperatures the capacitance is thickness dependent and equal to the geometric capacitance. At low frequencies and high temperatures it is thickness independent and equal to the Schottky barrier capacitance, which is determined by the doping density. Several methods of determining the activation energy of the donor centers from experimental capacitance versus frequency and temperature curves are suggested. The parallel equivalent conductance is also shown to be extremely frequency and temperature sensitive. It is found to have a pronounced maximum in both cases, which increases in magnitude and occurs at higher temperatures the thicker the insulator.

Capacitance Energy Level Spectroscopy of Deep-Lying Semiconductor Impurities Using Schottky Barriers

Abstract: The capacitance‐voltage (C‐V) relationship of a Schottky barrier diode is predicted for an energy distribution of impurity levels having spatially uniform concentration in an n‐type semiconductor. The model applies for forward and reverse bias voltages at modulation frequencies near dc and at modulation frequencies at which one or more of the deep doping levels cannot respond. Effects of partial ionization of impurity species and the effect of electrons in the depletion region are considered. It is predicted that the diode [d(1/C)/dV] versus V relationship exhibits sharp minima when the barrier height minus the applied bias is equal to the energy level relative to the conduction band edge of any of the predominant deep‐lying impurities in the semiconductor. The way in which deep lying impurities consequently affect a C‐V impurity profile analysis is discussed.

The physics of Schottky barriers

Abstract: A review is given of the physical processes which determine the height of the barrier and the current-voltage relationship in a metal-semiconductor Schottky barrier.

Characteristics of aluminum-silicon schottky barrier diode

Abstract: Aluminum n -type silicon Schottky barrier diodes with near-ideal characteristics have recently been developed. In this paper the characteristics of such a Schottky barrier are discussed. The I–V characteristics agree well with the theoretical thermionic emission model. The barrier height is determined from the saturation current, temperature dependence of forward current, and photoemission to be0.69±0.01eV. The switching measurements show no minority carrier storage, as expected. The low-frequency noise is very low and is comparable to the best p-n junction and guard-ring Schottky barrier. These desirable features, coupled with the simple process of the Al- n Si Schottky barrier, make them attractive in a variety of applications.

Low-frequency excess noise in metal—Silicon Schottky barrier diodes

Abstract: Theoretical models for the generation-recombination noise and trapping noise in metal-semiconductor Schottky barrier diodes are developed. Low-frequency excess noise in Schottky barrier diodes is found to be dominated by the modulation of the barrier height φB caused by fluctuation in the charge state of traps or generation-recombination centers. This noise mechanism does not occur in p-n junctions. The bias and the temperature dependence of the generation-recombination noise is critically compared with the experimental data for forward diode current ranges from 3 to 300 µA and operating temperatures from -25° to 100°C. Trapping noise in Schottky barrier diodes is observed at low temperatures in diodes not intentionally doped with deep level impurities. The experimental results on trapping noise can be described by assuming that the trap states have a constant capture cross section and are uniformly distributed in space, as well as in energy. The surface potential at the diode periphery also has an important effect on the Schottky barrier diode noise. The best low-frequency noise behavior is found when the surface is at the flat-band condition. An accumulated surface is always associated with a large amount of low-frequency excess noise.

Titanium-silicon Schottky barrier diodes

Abstract: Schottky barriers have been formed by vacuum evaporation of titanium onto chemically cleaned n- and p-type silicon. The barrier heights of the contacts were found to 0.50 and 0.61 eV for n- and p-type barriers, respectively. The barrier heights were determined from measurements of the 1 C 2 vs . V characteristics, the reverse saturation current density, and the activation energy of the reverse current. The effects of fabrication technique on diode properties are discussed. It is found that p-type diodes can be fabricated using standard oxide passivation techniques, without severe degradation of most diode properties; n-type diodes are severely degraded by the presence of silicon dioxide at the periphery of the diode, but this problem can be completely eliminated by the use of a diffused p-type ‘guard-ring’. Noise measurements are also presented for the p-type oxide-passivated diodes and for the n-type ‘guard-ring’ diodes; these diodes are found to have essentially ideal noise behavior above a few kHz.

Field effect semiconductor device having a protective diode

Abstract: A semiconductor device comprising a semiconductor element having an insulated gate electrode and a protective diode region provided in the neighborhood of the semiconductor element to protect the gate electrode from a dielectric breakdown; the diode is formed by a low resistivity semiconductor material to reduce its internal resistance, thereby accelerating the action of the protective diode so that the clamp action of the diode occurs earlier than the dielectric breakdown of the gate electrode.

The metal-semiconductor contact: an old device with a new future

Abstract: Advances in process technology are making possible the fabrication of Schottky barriers with reliable, ideal electrical characteristics. With these advances, one can anticipate a rapid increase in the utilization of Schottky barriers, not only as discrete devices but also as a new component in integrated circuits. This article presents a unified picture that quantitatively characterizes both the Schottky barrier and ohmic contacts on silicon. Fabrication techniques and various applications are also discussed.

Current-voltage characteristics at high fields in amorphous selenium thin layers

Abstract: The I–V characteristics of amorphous Se thin layers at high applied fields have been found to be I = I 0 exp (− βV 1 2 /kT) . The possible limiting mechanism (Schottky or Poole-Frenkel), corresponding to such a dependence, is analyzed and an explanation based on a particular band model (Simmons) is proposed.

Use of a double diffused guard ring to obtain near ideal I V characteristics in Schottky barrier diodes

Abstract: This paper reports the use of a unique double-diffused guard ring Schottky barrier diode. The electrical characteristics of the conventional Schottky barrier diode are compared with the single and double guard ring devices. It is shown that both guard ring devices give near ideal I–V characteristics by eliminating the edge effects inherent with metal-semiconductor contacts. It is also shown that the double guard ring structure maintains the fast recovery time of the Schottky diode to higher current levels than the single ring structure by suppression of minority carrier injection.

Nuclear Detectors from Cadmium Telluride Grown from a Tellurium Solvent

Abstract: Highly perfect and pure single crystalline CdTe, grown by the traveling heater method, has been used to fabricate gamma ray detectors. Using tellurium as the solvent, carrier concentrations as low as 5 × 109 have been obtained in as-grown material. The detectors were formed by using back-to-back Schottky barriers on opposite sides of the CdTe slice. Operation over the temperature range from + 125 to -150 °C has been observed. Excellent agreement of the experimental spectra with a theoretical model which considers the mean free drift length of both electrons and holes has been obtained. Although the energy resolution is not yet of spectroscopic quality, the detector performance is more than adequate for application to some practical devices.

Contact Properties of Metal-Silicon Schottky Barriers

Abstract: Barrier heights of Schottky diodes prepared by vacuum depositions of metals onto chemically etched silicon surfaces were investigated by measuring the current-voltage and capacitance-voltage characteristics. The barrier height varied remarkably with the work function of metal and the sum of the barrier heights measured on n-type and p-type silicon was nearly equal to the energy gap of silicon. The results were well explained by applying the theory of Cowley and Sze, leading to the conclusion that the Fermi level is not always pinned at the semiconductor surface.

Voltage‐Current Characteristics for Electrical Conduction Through Thin MgO Films

Abstract: The voltage‐current characteristics of Au–MgO–Au thin‐film emission diodes formed by electron beam evaporation of Au and MgO are consistent with an expression derived for Schottky field emission into the conduction band of the oxide. These results however indicate a potential barrier height of about 0.72 eV when determined from the zero‐field intercept of the straight line logI vs V1/2 plot and about 0.33 eV when obtained from an Arrhenius plot. These apparent barrier heights were different for devices fabricated by depositing the MgO film in an oxygen atmosphere. The apparent barrier height determined from the zero‐field intercept went up for increasing oxygen pressure and the barrier height determined from the Arrhenius plot went down. Emission of electrons into vacuum was observed from each device at very low sample biases indicating that preferential emission through pinholes in the Au overlayer was occurring.

A 1 to 2 µm silicon avalanche photodiode

Abstract: Avalanche photodetection at wavelengths beyond the silicon band edge has been observed in palladium-silicon Schottky diodes. The devices are analogous to vacuum photomultipliers in that photo-excitation and gain take place in separata regions of the diode. Quantum efficiencias of 0.75 percent and avalanche multiplications > 200 have been observed at 1.3 µm.

A hot carrier pn-diode

Abstract: Disclosed is a Schottky barrier or hot carrier diode and process for making same wherein a diffused PN junction and a Schottky barrier junction are both formed in a body of semiconductor material. The diffused PN junction is formed by first diffusing an impurity through an opening in a diffusion mask and into one surface of the semiconductor body to form PN junction. Next, a large central portion of the region formed by the above diffusion is removed by etching or cutting, leaving unaffected by the etchant only that portion of the diffused region underlying and adjacent to the diffusion mask on the surface of the semiconductor body. The latter portion of the diffused region forms a relatively small area diffused PN junction. Finally, a Schottky barrier junction is formed in the etched out area of the semiconductor body, and the diode including the diffused and Schottky barrier junctions has a near-ideal current-voltage characteristic and still maintains its fast recovery time.

The measurement of doping profiles in thick epitaxial layers of GaP using Schottky barrier C-V data

Abstract: Using a Schottky diode technique investigations have been made of the variation in carrier concentration through epitaxial layers of GaP grown by liquid epitaxy and vapour transport methods using tellurium, sulphur and zinc as principal dopants. In all cases it is found that the carrier concentration alters significantly over the thickness of the grown layer and in some cases by as much as two orders of magnitude. The measured values of Hall concentration in the layers are weighted towards the higher levels of doping and are often not indicative of surface carrier concentration. This creates difficulties in trying to predict the electrical properties of epitaxial p - n junction diodes from Hall measurements alone.

Schottky barrier diode

Abstract: Anisotropic etching is employed in the fabrication of a Schottky barrier diode to provide a recessed geometry having a guard ring of reduced area, thereby avoiding the objectionable degree of parasitic capacitance found in related planar devices. A low series resistance is also provided since the anisotropic etching step inherently permits a precise control of the distance between the surface barrier and a buried substrate layer of low resistivity.

One-electron and phonon-assisted tunneling in n-Ge Schottky barriers

Abstract: Metal-Ge n-type semiconductor tunnel junctions, discussing Sb and As doped units and conductance and barrier heights air cleavage effects

Deep Energy Levels in the High Resistance Region at GaAs Vapor Epitaxial Film-Substrate Interface

Abstract: In order to find the energy levels of the deep centers that cause a high resistance region at the interface between GaAs vapor epitaxial film and the substrate, three kinds of measurements were performed: i) time dependence of the capacitance of Schottky barriers, ii) temperature dependence of the reverse current of Schottky barriers, iii) photoconductivity of the high resistance region. From the variation in the time dependence of the capacitance measured at various temperatures, an activation energy for electrons at deep traps was found to be about 0.89 eV. When the depletion layer contained a high resistance region, the reverse current of the Schottky barrier was larger than the normal reverse current by about three orders of magnitude. The measured results on the temperature dependence of reverse current and on the photoconductivity spectrum of the high resistance region suggest the presence of three deep energy levels that range from about 0.3 eV to 0.6 eV above the valence band. Extrinsic negative photoconductivity was observed in the high resistance region.

A diode-coupled bipolar transistor memory cell

Abstract: A 30 mil2memory cell employing Schottky diodes and epitaxial sheet resistors will be described. In large arrays, expected cycle time is 60 ns and standby power is 75 μW. Projected store cost is one cent per bit.

Schottky barrier transit time negative resistance diode circuits

Abstract: In a preferred form, a negative resistance diode comprises a semiconductor wafer contained between two Schottky barrier contacts. The diode is biased below avalanche breakdown, but above a critical "reach-through" voltage, which, with appropriate diode parameters and an appropriate external circuit, causes minority carriers to be injected by the forward-biased contact to give a transit time negative resistance. When used as an oscillator, the device gives a significantly lower noise figure than analogous Impatt diodes. Amplifier and voltage limiter embodiments are also described.

Neutron Displacenent Effects in Epitaxial Gunn Diodes

Abstract: To correlate the performance of Gunn diodes in a radiation environment with the radiation-induced defects in the active epitaxial layer of the device, radiation effects on Gunn diodes and Hall bars grown simultaneously were investigated. This paper will assess the results that indicate that neutron-induced degradation in device efficiency is due to carrier removal, reduction of the peak-to valley-current ratio by low-field mobility degradation, and slow trapping of high-field conduction electrons.

Two-watt CW GaAs Schottky-barrier IMPATT diodes

Abstract: New high power (CW) at X-band from GaAs Schottky-barrier diodes was achieved as a result of improved heat sink and Schottky-barrier contact formation techniques. An output power of 2.1 watts (CW) at 9.2 GHz with an efficiency of 9 percent was obtained from a diode mounted on a diamond heat sink with the Schottky-barrier contact adjacent to it. The measured thermal resistance was about 7°C/W. The diodes were fabricated using platinum and molybdenum on n-type epitaxial GaAs substrate.

Surface properties of cadmium selenide

Abstract: The properties of CdSe real surfaces were determined by measuring the C-V characteristics of MIS capacitors formed by vacuum deposition of SiO on different faces of CdSe crystals The total charge in the surface states at flat band was obtained from measurements of the flat band voltage for various insulator thicknesses on the basal and cleavage planes The separation of the fast and slow states and the energy distribution of the fast states on the two crystal faces was determined from the displacement of the experimental from the theoretical curves as the Fermi level was swept through the forbidden gap The density of fast surface states (acceptor type) is not large enough to cause pinning of the Fermi level observed in Schottky barrier diode experiments Apparently the oxide reduces the surface state density on CdSe below that obtained on an uncoated surface

Schottky barrier diode

Abstract: A Schottky barrier diode includes a body of a semiconductor material of one conductivity type having a guard ring region of the opposite conductivity type therein at a surface of the body. The guard ring extends along the surface of the body in a closed path. A layer of an insulating material is on the surface of the semiconductor body and has an opening therethrough extending to the area of the semiconductor body surface within the guard ring. A metal layer is on the surface of the semiconductor body within the opening in the insulating layer and forms a surface barrier rectifying junction with the semiconductor body. The metal film is also coated on the insulating layer and extends over the guard ring.

An Automatic Test Set for Measuring the Doping Profile of Semiconductor Epitaxial Layers

Abstract: The characteristics and the electronic circuit of an automatic test set which can perform the measurement of doping profile of a semiconductor epitaxial layer are reported The doping profile presentation is on an X‐Y plotter The technique used is that of realizing a Schottky barrier on the epitaxial film and of measuring the capacitance and its derivative vs the reverse voltage applied to the junction An analog elaboration of this information, according to the Schottky barrier diode equations, finally gives the desired doping profile Experimental results on different epitaxial layers are reported If the geometrical dimensions of the Schottky barrier diode are known, an absolute calibration of the carrier concentration is possible

REVERSE I‐V CHARACTERISTICS OF THE Na–Si SCHOTTKY BARRIER

Abstract: The Schottky barrier height at the interface between metallic sodium and vacuum‐cleaved n‐type Si has been found to be 0.43±0.02 eV. Ther barrier height was determined from measurements of the reverse current‐voltage characteristic of Schottky diodes in a vacuum of 10−8 Torr and at 288°K. The measured value is close to the results of other workers on the alkaline‐earth metals and shows that the barrier height is strongly controlled by the surface‐state density at the metal‐semiconductor interface.