Showing papers on "Schottky diode published in 1971"

Studies of tunnel MOS diodes, I. Interface effects in silicon Schottky diodes

Abstract: A theoretical and experimental study has been made of silicon Schottky diodes in which the metal and semiconductor are separated by a thin interfacial film. A generalized approach is taken towards the interface states which considers their communication with both the metal and the semiconductor. Diodes were fabricated with interfacial films ranging from 8 to 26 A in thickness, and their characteristics are related to this model. The effects of reduced transmission coefficients together with fixed charge in the film are investigated. The interpretation of the current-voltage characteristics and the validity of the C−2-V method in the determination of diffusion potentials are discussed.

Electrical Properties of Semiconductor Photodiodes with Semitransparent Films

Abstract: High speed photodiodes with semitransparent film-semiconductor junctions, which behave as Schottky barriers, are designed and prepared. The optimized width of the depletion layer of the photodiode is calculated for the selected cut-off frequency. The relations between transmittance and sheet resistivity are studied with some films of semiconducting compounds, which affect the gain and response time of photodiodes. The photodiodes, fabricated by the deposition of the semitransparent films of CdS or CU2Se on Si, have high frequency response and the cut-off frequency of Cu2Se-n.Si photodiodes is higher than 4 GHz.

Recombination velocity effects on current diffusion and imref in schottky barriers

Abstract: A detailed theoretical treatment is given of the effects of a thermionic velocity boundary condition on diffusion transport of majority carriers and the spatial variation of the majority carrier quasi-Fermi potential (imref) in metal-semiconductor (Schottky) diodes. Diode parameters such as n(={kT/q[dlnJ/dV]}−1) and Js, the reverse saturation current are calculated for the case of parabolic band bending. These results are expressed in terms of the Dawson function, the solution to the differential equation d D(y) d y = 1 − 2yD(y) . In contrast to recent estimates of ≅ 1·06 for typical conditions, the parameter n is shown to be slightly bias dependent, to have a value of less than 1·01 for typical operating conditions and a maximum value of 1·28 for forward bias ≅ 2kT/q from flat band. A calculation of spatial variation of imref in the same case shows that under moderate forward bias the electron imref is very nearly constant through the depletion region. For reverse bias the imref rapidly deviates from constancy for applied bias in excess of kT/q. Diffusion effects on T-F emission are shown to be very small.

Schottky barriers on p-type silicon

Abstract: Measurements have been made of the electrical characteristics of Schottky barriers made by evaporating films of various metals (Al, Pb, Ni, Au, Ag, Cu) onto p-type silicon. The barriers were generally lower than on n-type silicon, and in the case of Au the barrier was so low as to provide an effectively ohmic contact at room temperature. The truly exponential portion of the forward I–V characteristic was restricted to a comparatively small voltage range. Within this range ‘n’ values of about 1.10 were obtained. The reverse characteristics could be explained in terms of generation in the depletion region. The variation of barrier height with metal work-function indicates that the surface-state parameters (density of states and position of neutral level) are essentially the same for p-type as for n-type silicon. This is confirmed by the fact that, for a given metal, the sum of the barrier heights on n-type and p-type silicon is approximately equal to the band-gap.

Flicker noise in metal semiconductor Schottky barrier diodes due to multistep tunneling processes

Abstract: In a practical metal semiconductor Schottky barrier diode there is a certain amount of current flow by indirect tunneling through the barrier. Although this component of current is negligibly small compared to the thermionic emission or thermionic field emission current, a large low-frequency 1/f noise is associated with this multistep tunneling process. The multistep tunneling current introduces a random fluctuation of charge density at the trap states, which trap current carriers during the indirect tunneling process, in the space-charge region of the diode. The field intensity at the metal semiconductor interface is therefore modulated, which in turn modulates the Schottky effect and produces a random fluctuation of the diode current. The spectral intensity of noise due to this mechanism is calculated. Large flicker noise is expected at low frequencies.

Epitaxy of Silicon Doped Gallium Arsenide by Molecular Beam Method

Abstract: The molecular beam method is a versatile experimental technique which may be used to grow high quality single crystal thin films in the range from 100A to several microns with precise control of uniformity and thickness. Films may be doped by an additional molecular beam containing the doping material simultaneously impinging on the substrate surface with the film molecular beams. Epitaxial GaAs thin films doped with silicon were grown by the molecular beam method in an ultrahigh vacuum system in which high energy electron diffraction and mass spectrometric measurements could be made during growth or by stopping growth momentarily. The crystallinity and beam intensity parameters of these films were thus studied during growth. The doping profiles and the amount of compensation were evaluated by the Schottky barrier diode method and the photo luminescence spectra.

Microwave mixer and detector diodes

Abstract: Recent advances in microwave mixer and detector diodes are reviewed. Devices considered are germanium back diodes, silicon and gallium arsenide point-contact diodes, and Schottky-barrier diodes. Current work on low-barrier (n-type) Schottky diodes and high-burnout point-contact diodes is also described. Experimental results of CW and RF pulse burnout of these devices are summarized. Different approaches to improve the power-handling capability of Schottky diodes at S-, X-, and K u -band frequencies are considered.

Thermal Effects in Amorphous‐Semiconductor Switching

Abstract: It is shown that a pure thermal model, in the absence of significant heating of the electrodes, gives no negative differential resistance and no high‐current filaments. When some electronic effects, such as space charge, narrow Schottky barriers, or field‐enhanced conductivity, are explicitly introduced, negative‐resistance regions and filamentary conduction exists.

The Volumes of Formation of Schottky Defects in Ionic Crystals

Abstract: Abstract In this paper we calculate the volumes and energies of formation of Schottky defects in the alkali halides NaCl, NaBr, KCl and KBr. Both the polarisable point-dipole and a simple shell model are evaluated. The calculation uses a generalised and extended Mott-Littleton approach in conjunction with results derived previously by the lattice statics method of Kanzaki. The polarisable point-dipole model, as might be expected, is bad, but the shell model leads to good values for the Schottky formation energies, which not only compare well with experiment but are insensitive to the size of the region (‘region I’) around the defect for which the lattice displacements are computed explicitly (i. e. as distinct from the outer Mott-Littleton region, ‘region II’) . The predicted volumes of formation of Schottky defects are less than the molecular volume, νm, i. e. the volumes of relaxation are negative (NaCl, - 0.69 vm; NaBr, - 0.73 vm; KCl, - 0.52 vm; KBr, -0,51 vm in the static lattice approximation). This is in conflict with the results of experiments on the effect of pressure upon the ionic conductivity of these crystals although some other experimental data are consistent with negative relaxation volumes. The disagreement is briefly discussed and the possibility that temperature effects are greater than is implied by the quasi-harmonic model is noted as a possible explanation

Infrared Detection by Schottky Barriers in Epitaxial PbTe

Abstract: High‐quality infrared detectors have been made from Pb Schottky barriers on epitaxial PbTe layers. At 77 °K these devices are limited by the 300 °K background at f/1.7 and attain Johnson noise‐limited peak detectivities [Dλ*(5.5 μ m, 600, 1)] of 6×1011 cm Hz1/2W−1 with further reduction of the background. The diode quantum efficiencies reach 50–60%.

Chapter 2 The Voltage–Current Characteristic of Metal–Semiconductor Contacts

Abstract: Publisher Summary This chapter reviews the progress made since 1962 in the understanding of the voltage–current (V–I) characteristic of Schottky barriers Theories pertaining to ideal Schottky barriers are given and suggested that the V–I characteristic of a metal semiconductor contact is given by the diode theory In practice, such a barrier is hard to attain and difficulties such as nonuniformity of the barrier height, or the charge density, or the existence of an interface layer between the metal and semiconductor will alter markedly the V–I characteristic It is reported that the situation of the state of understanding of the V–I characteristic of Schottky barriers depends on the semiconductor carrier concentration considered In this chapter emphasis is given to results obtained in the case of barriers made on III–V semiconductor compounds It is quite evident that most of the results described in this chapter are not particular to III–V compounds and can be applied to other semiconductors

Avalanche region width in various structures of IMPATT diodes

Abstract: The avalanche region of one-sided and two-sided abrupt junctions has been studied. These are the structures most commonly utilized for IMPATT diodes. Numerical results are presented which show that n+-p Si diodes have much narrower avalanche regions, due to the unequal ionization rates in Si, than the complementary p+-n type. The implications of these results with respect to IMPATT diode design are discussed.

Schottky contact devices and method of manufacture

Abstract: A method is described for making plural semiconductor devices containing a Schottky contact by providing on one side of a semiconductor wafer a metal layer to form the Schottky contact, and then subjecting the opposite side of the wafer to an etching treatment which attacks the semiconductor but not the Schottky metal until semiconductor portions are etched away leaving spaced semiconductor islands whose contact surface with the Schottky method is surrounded by free surface portions of the metal. Then the metal layer is severed along lines spaced from the islands to leave in the final device, an exposed metal surround to increase the breakdown voltage.

Green Injection Luminescence from Forward-Biased Au-GaP Schottky Barriers

Abstract: Improvements in the minority‐carrier injection efficiency of GaP Schottky diodes are achieved by the incorporation, into the device, of a thin insulating layer separating the metal and the semiconductor. This enables visible green luminescence to be obtained from the diodes in forward bias. Measurements of the optical and electrical characteristics of this device are reported.

Local-oscillator noise in a silicon Pt--n--p + microwave diode source

Abstract: Measurements of the noise of an experimental silicon Pt–n–p+ transit-time diode used as a local oscillator at a frequency of 11.8 GHz are described. The results show that the relatively noisefree performance of the diode should make it useful, particularly for high-frequency applications where low-noise sources are not readily available.

Semiconductor device embodying field effect transistors and schottky barrier diodes

Abstract: A semiconductor device having at least one FET and at least one Schottky barrier diode. The device has an FET with source and drain regions in a semiconductor body and a gate electrode. The Schottky barrier diode consists of a thin layer of polycrystalline material separated from the semiconductor body by an insulating amorphous layer, an ohmic contact, and a barrier contact. The combination is particularly useful in fabricating logic and memory devices where the Schottky barrier diode is utilized as a resistance element and/or as an input output device. In the method of producing the device, a polysilicon layer is used to fabricate both the gate electrode and the Schottky barrier diode.

Hafnium‐Silicon Schottky Barriers: Large Barrier Height on p‐Type Silicon and Ohmic Behavior on n‐Type Silicon

Abstract: Schottky‐barrier diodes of Hf on p‐type Si gave a height φMS = 0.90 eV, which is the largest value of φMS reported to date on Schottky barriers on either p‐ or n‐type Si. Excellent agreement was found between the φMS values determined from current‐voltage, activation energy, and capacitance‐voltage analyses. This large value of φMS of the Hf‐(p)‐Si Schottky barrier allows several new applications which were not possible before in the integrated circuit technology, such as clamping of p‐n‐p transistors and fabrication of enhancement‐mode p‐channel Schottky gate field‐effect transistors. Hafnium deposited on n‐type Si (ND≅5×1015 cm−3) gave Ohmic behavior suggesting the validity of the work‐function‐difference model for the Hf–Si system. Under this assumption, the Schottky‐barrier analysis gives the work function of Hf=4.23±0.02 eV.

Doping dependence of the barrier height of palladium-silicide Schottky-diodes

Abstract: Capacitance-voltage and current-voltage measurements have been used to determine the barrier height of palladium-silicon Schottky diodes. All diodes were heat-treated to form palladium silicide and the doping range of the silicon was varied in the range 5 × 1015 cm−3 to 2 × 1018 cm−3. The zero-electric-field (flat-band) barrier height was found to be independent of doping concentration in the above range, having a value 0·75 ± 0·01 eV. On the other hand the zero-bias barrier height is more electric-field dependent than the predictions of the usual image-force theory. However, the results are well described by an additional barrier lowering term of the approximate form Δφ = −χmϵm where ϵm is the maximum junction electric-field and χm a characteristic length in the region of 20–40 A.

Transistor logic circuit

Abstract: A transistor-transistor logic circuit employing a Schottky barrier diode connected across the output of the multi-emitter input transistor and the reference potential to suppress transient overshoot by controlling the voltage at the collector of the input transistor of the TTL circuit

Planar mesa Schottky barrier diode

Abstract: Planar silicon technology has been used to fabricate mesa Schottky barrier diodesh with high breakdown voltages. This method proves to be superior to alternate methods used to increase the breakdown voltage of Schottky diodes. The processing techniques and characteristics of mesa Schottky diodes are described in this paper.

Influence of carrier velocity saturation in the unswept layer on the efficiency of avalanche transit time diodes

Abstract: Due to velocity saturation of the carriers, the series resistance caused by the unswept layer in avalanche transit time diodes increases with increasing ac voltage on the diode. In GE npp+diodes this effect is found to influence the efficiency considerably and the same may be true for Si npp+diodes.

Current Transport, Effective Dielectric Constant, and Temperature of Ta2 O5 Thin Films

Abstract: The I‐V characteristics of Ta–Ta2O5–Au thin‐film devices indicate high temperatures and large dielectric constants for both Schottky and Poole‐Frenkel dominated conduction. The effects of space charge and electron effective mass are also indicated.

Electro-optical coupled-pair using a schottky barrier diode detector

Abstract: There is disclosed an electro-optical coupled pair utilizing a Schottky barrier diode detector in combination with a light source in which in the preferred embodiment the bottom portion of the Schottky barrier diode is hollowed out by anisotropically etching the wafer used for the diode to provide the hollowed-out portion with smooth inclined sidewalls over the light source for coupling light generated laterally into the wafer. Because of the anisotropic etching, the sidewalls serve to couple a much greater percentage of the generated light into the diode to produce more electron-hole pairs, and therefore more external signal. This configuration thus captures non-vertically generated light which would otherwise be lost, thus increasing the efficiency of Schottky diode detectors and the coupled pair.

Method for Doping Thin Insulating Films and the Comparison between the Electrical Characteristics of Undoped and Doped Films

Abstract: A technique has been developed for doping thin dielectric films with either positive or negative ions from aqueous solution. The experimental investigations were made on 60–400‐A thick aluminum oxide films. The influence of doping on Schottky or Poole‐Frenkel emission was shown by comparison of the electrical characteristics of the doped and undoped films. The predominating mechanisms are, for thin (<100 A) films, Shottky emission; for thick (400 A) films, Poole‐Frenkel emission; and for films of intermediate thickness (∼200 A) Poole‐Frenkel and Schottky for doped and undoped, respectively.

Control circuitry and voltage source for use with charge storage diode

Abstract: A control circuit consists of essentially a first charge storage diode and means for creating a reservoir of minority carriers within the first diode which, when desired can be utilized to almost instantaneously cause minority carriers to be created in a second charge storage diode. The second diode is useful as a switch which, for a preselected period of time, becomes a short circuit that allows current flow in the reverse direction through the diode, but then automatically becomes an open circuit. A voltage source, especially adapted for use with the control circuit is also described.

pn‐Schottky Hybrid Cold‐Cathode Diode

Abstract: The device is a forward‐biased GaAs0.6P0.4 pn‐junction diode whose thin p layer is coated with a cesiated film of either Ag or Au 100–300 A thick. In some cases the diodes are heat treated at 250 °C before cesiation. A cathodic emission efficiency of 1.4% is obtained at 10 A cm−2 for a heat‐treated diode with a 100‐A‐thick Au film. The emission is uniform over the coated surface and is proportional to exp(qV/kT). Preliminary data indicate long life for the device when operated in an ambient of Cs vapor.

Method of producing schottky diodes

Abstract: 1. A METHOD FOR PRODUCING HIGH AND LOW THRESHOLD SCHOTTKY DIODES IN AN INTEGRATED CIRCUIT, COMPRISING DIFFUSING A PLURALITY OF N-CONDUCTING ZONES HIGHLY DOPED WITH ONE OF THE GROUP INCLUDING ARSENIC OR ANTIMONY INTO A P-CONDUCTIVE SEMICONDUCTOR SUBSTRATE, DIFFUSING A PHOSPHOROUS DOPED REGION INTO ONE OF THE ZONES, EPITAXIALLY PRECIPITATING A N-CONDUCTING SEMICONDUCTOR LAYER OVER THE SURFACE OF THE SUBSTRATE INTO WHICH THE N-CONDUCTING ZONES HAVE BEEN DIFFUSED, DIFFUSING THE PHOSPHOROUS DOPED REGION INTO THE LAYER UP TO THE SURFACE OF THE LAYER AND ARRANGING A METAL CONTACT ON THE SURFACE OF THE LAYER IN CONTACT WITH THE PHOSPHOROUS DOPANT IN THE LAYER DIFFUSING THROUGH THE LAYER A SECOND PHOSPHOROUS DOPED REGION DOWN TO SAID ONE ZONE AND A THIRD PHOSPHOROUS DOPED REGION DOWN TO A SECOND OF THE ZONES, DIFFUSING RESPECTIVE HIGHLY DOPED N-CONDUCTIVE REGIONS INTO EACH OF THE SECOND AND THIRD PHOSPHOROUS DOPED REGIONS, ARRANGING RESPECTIVE METAL CONTACTS ON THE LAYER IN CONTACT WITH EACH OF THE N-CONDUCTIVE REGIONS AND ARRANGING A METAL CONTACT ON THE LAYER ABOVE THE SECOND ZONE, THE LAYER AND THE METAL CONTACTS ARRANGED THEREABOVE FORMING HIGH AND LOW THRESHOLD SCHOTTKY DIODES AND THE METAL CONTACTS IN CONTACT WITH THE N-CONDUCTIVE REGIONS FORMING THE OTHER ELECTRICAL CONNECTIONS OF THE RESPECTIVE SCHOTTKY DIODES.

Programmable fixed data memory utilizing schottky diodes

Abstract: A memory element comprises two series-connected and series-opposed Schottky diodes. A middle electrode is provided between the Schottky diodes. To effect programming, the Schottky diode which is operated at reverse voltage is short-circuited to the middle electrode through the formation of a breakthrough channel.

Theoretical study of microwave oscillation efficiency in improved read diodes

Abstract: An oscillation efficiency up to 28 per cent was obtained at 10 GHz in the computer simulation of large-signal operation of an improved Si Read Diode. The diode has a Schottky barrier instead of a p-n junction in order to avoid the harmful minority-carrier-storage effect. Temperature was found to have a drastic effect on efficiency. When an operating temperature of 600°K was considered efficiency was reduced to 3.8 per cent. The structures analyzed have a narrow avalanche region as in Read's original proposal in contrast to the “extended-cathode” Read diode studied by Scharfetter and Gummel. The diode is operated preferably at such a high bias current that the small-signal negative resistance is disappearing. In this way the diode requires less reactive current and the parasitic series resistance has less detrimental effect.