Showing papers on "Schottky barrier published in 1968"
01 Aug 1968
TL;DR: In this article, the Schottky barrier contacts for the source and drain have been used for insulated gate field effect transistors (IGFETs) with similar electrode geometry.
Abstract: Insulated-gate field-effect transistors using Schottky barrier contacts for the source and drain have been studied. At room temperature, the device characteristics are Comparable to conventional IGFET's with similar electrode geometry. At lower temperatures, the current transport is by tunneling of carriers from the metal across the Schottky barrier to the semiconductor inversion layer.
166 citations
TL;DR: In this paper, the forward and reverse I-V characteristics of Schottky barrier diodes with PtSi contacts and diffused guard rings were investigated and the forward current was shown to follow the expression I f = I s exp (qV/nkT) over eight orders of magnitude in current with I s = 10−12 A and n = 1.02.
Abstract: Metal-semiconductor diodes with near-ideal forward and reverse I-V characteristics have been fabricated using PtSi contacts and diffused guard rings. Typically, for a device with an area of 2.5 × 10−6 cm2 made on an n-type (111) oriented, 0.35 ohm-cm silicon epitaxial substrate, the forward current follows the expression I f = I s exp (qV/nkT) over eight orders of magnitude in current with I s = 10−12 A and n = 1.02. The reverse breakdown is sharp and occurs at the theoretical breakdown voltage of p+ n silicon junctions of the same n-type doping. The premature breakdown observed in nearly all previous Schottky barrier diodes has been shown to be caused by electrode sharp-edge effects. Besides giving sharp breakdown voltage, the guard ring also eliminates anomalously high leakage currents, yet still retains the fast recovery time characteristic common to other Schottky barriers. Typically, the recovery time measured at 10 ma is less than 0.1 ns, the resolution of the measurement.
162 citations
TL;DR: In this article, a review of the present situation and difficulties encountered in analyzing the experimental data lead to a new method of evaluation of these data. And the reverse characteristic is compared with the photoresponse, showing that thermionic emission is the dominant electron transport mechanism.
Abstract: Results of the study of AuGaAs Schottky barriers at room temperature and above are presented. A review of the present situation and difficulties encountered in analyzing the experimental data lead to a new method of evaluation of these data. In this method, the reverse characteristic is compared with the photoresponse. As a result, thermionic emission is shown to be the dominant electron transport mechanism. A value of the effective mass is obtained which can be used to characterize the electron population at the top of the barrier. This value indicates that contrary to previous estimates, electron scattering is relatively unimportant over the distance between the metallurgical junction and the top of the barrier. Finally several possible sources of discrepancy between theory and experiment are reviewed indicating that the influence of traps cannot be neglected.
51 citations
TL;DR: In this article, the bias dependence of the photoelectric barrier energy of n-GaAs-Al diodes has been measured by extrapolation of the photoresponse vs. photon energy plots.
Abstract: The bias dependence of the photoelectric barrier energy of n-GaAs-Al diodes has been measured. The devices were fabricated by cleavage of the GaAs in an evaporating stream of metal in a vacuum of 10^(−8) torr. The barrier energies at various bias levels were determined by extrapolation of the photoresponse vs. photon energy plots. The electric field dependence of the photoresponse was also measured at constant photon energy. The calculated change in barrier energy from the latter method was then compared with the changes in extrapolated values of barrier energy. A small systematic disagreement was observed and attributed to the effects of collection efficiency in the GaAs. The field dependence of Schottky barriers on 5×10^(16) GaAs was found to be in good agreement with that expected from the exponential charge distribution associated with the surface states which determine the barrier energy.
49 citations
TL;DR: In this paper, the voltage and time dependence of the capacitance was analyzed using a modified version of Goodman's model for traps in depletion layers and the results yield a concentration of the dominant active trap of 1 −4×1016 cm−3 in all the crystals examined.
Abstract: Dark capacitance measurements have been made on Au–GaAs Schottky barriers using boat‐grown, oxygen‐doped n‐type GaAs with room‐temperature carrier concentrations from 2×1013 to 4×1016 cm−3. The voltage and time dependence of the capacitance was analyzed using a modified version of Goodman's model for traps in depletion layers. The results yield a concentration of the dominant active trap of 1–4×1016 cm−3 in all the crystals examined. From the variation in the time dependence of the capacitance in the range 275°–365°K, the energy for the emission of an electron from this trap is 0.90±0.02 eV. Other aspects of the capacitance data locate this trap at around 0.7 eV below the conduction band, which is the energy previously assigned. Another, faster time‐dependence observed in the higher‐resistivity material was investigated in the range 225°–255°K. The activation energy associated with the latter time dependence is found to be 0.7 eV. The behavior of the capacitance at high reverse bias is explained in terms of electron capture by the dominant trap as the current increases due to impact ionization.
48 citations
TL;DR: In this article, the authors performed noise measurements on forward and reverse-biased silicon Schottky barrier diodes in the frequency range of 100 Hz to 50 kHz and found that the noise was in agreement with shot-noise theory.
Abstract: Noise measurements have been performed on forward and reverse-biased silicon Schottky barrier diodes. Measurements were performed in the frequency range of 100 Hz to 50 kHz. Apart from excess noise observed for some diodes in a portion of this frequency range, the noise for the diodes was found to be in excellent agreement with shot-noise theory. Some refinements of the shot-noise theory have been considered, but the difference between the refined and the simple theories was not resolvable in our measurements. A useful noise-measurement technique is described.
43 citations
TL;DR: In this article, a simple method is described to allow the use of thermally stimulated conductivity (TSC) measurements for low-resistivity semiconductors, where a p−n junction or Schottky barrier is formed to provide the required high resistivity region.
Abstract: A simple method is described to allow the use of thermally stimulated conductivity (TSC) measurements for low‐resistivity semiconductors. A p‐n junction or Schottky barrier is formed to provide the required high‐resistivity region. Trap populations can be inverted either by light or by changes in diode bias, but different traps may be seen in each case. The accuracy of trap concentration determinations is improved over ordinary TSC measurements since the gain is close to unity, and the active volume can be accurately found from capacitance measurements. The use of the method is demonstrated by the measurement of trap energies and densities in a sample of GaAs0.5P0.5 alloy with an electron concentration of about 1015 cm−3. Two main traps were seen, one at 0.20 eV from the conduction band and the other at 0.41 eV from the valence band, with concentrations of, respectively, 1×1014 cm−3 and 5×1014 cm−3. The method has also been successfully applied to silicon.
41 citations
TL;DR: In this paper, capacitance and photoresponse measurements on n-type and p-type SiC were performed and it was shown that the barrier height at the interface is fixed by surface states at the middle of the energy gap.
Abstract: Metal—semiconductor Schottky barrier contacts on SiC have been made both by cleaving single crystals of SiC (6H and 15R polytype) in ultrahigh vacuum in a stream of evaporating metal, and by evaporating metal onto etched surfaces Results of capacitance and photoresponse measurements on n‐type and p‐type samples are presented The barrier height on n‐type samples is 145(±010) eV, independent of the work function of the metals (Au, Ag, Al) Nearly the same value is found for Al contacts on p‐type SiC When Au contacts are used, the barriers on heavily doped p‐type crystals spread from 090–125 eV The results for the purer n‐type samples show that the Fermi level at the interface is fixed by surface states at the middle of the energy gap
35 citations
Patent•
IBM1
TL;DR: A Schottky-barrier field effect transistor is characterized by a zone or region of higher conductivity which extends from the vicinity of the source electrode to near the gate electrode as discussed by the authors.
Abstract: A Schottky-barrier field-effect transistor is disclosed with a semiconductor channel of relatively low conductivity between the source and drain electrodes which may be electrically influenced by a Schottky-barrier gate electrode located on the semiconductor channel. The transistor is characterized by a zone or region of higher conductivity which extends from the vicinity of the source electrode to near the gate electrode. Further, source and drain regions are conveniently provided for the transistor of semiconductor of the same conductivity type as the channel semiconductor at the Schottky-barrier electrode. Advantageously, the drain region may be made of semiconductor of high conductivity and the same conductivity type as the source region. The high conductivity region may be achieved through either diffusion or epitaxial growth technique.
27 citations
TL;DR: In this article, a Schottky barrier was proposed to eliminate the injection of minority-carriers from the collector into the base region, as well as minority charge storage in the collector region.
Abstract: In saturated switching conventional n-p-n or p-n-p junction bipolar transistors the turn-off speed is limited by storage-time. The conventional way to reduce storage time is to control minority-lifetime by gold-doping. But gold-doping also decreases β, which is proportional to the minority lifetime, hence cannot eliminate the problem. The storage-time can be practically eliminated by replacing the conventional p-n collector junction by a Schottky-barrier, with the metallic side forming the collector region. This eliminates the injection of minority-carriers from the collector into the base region, as well as minority charge storage in the collector region. Theoretically the storage-time is thereby approximately β times less than that of the best possible gold-doped transistor with similar geometry and β.
24 citations
TL;DR: In this paper, the positive charge buildup produced in silicon dioxide by low energy electrons (0 to 30 keV) has been investigated as a function of beam energy and oxide thickness, as evidenced by displacement of capacitance versus voltage plots, and the induced charge, as well as the beam energy dissipated within the oxide in the vicinity of the oxide-silicon interface.
Abstract: The positive charge buildup produced in silicon dioxide by low energy electrons (0 to 30 keV) has been investigated as a function of beam energy and oxide thickness. The induced charge, as evidenced by displacement of capacitance versus voltage plots, was found to be a function of the beam energy dissipated within the oxide in the vicinity of the oxide-silicon interface. The charge induced at a particular fluence level in an oxide of given thickness increases with energy up to some level E max beyond which the charge buildup rate falls off as the energy is increased further. Continued falloff in the buildup rate was observed in several samples irradiated at energies of 200 keV and 1 MeV. E max has been found to correspond to the beam energy which, according to predicted range-energy data, produces maximum energy dissipation per unit path length in the oxide near the silicon interface. Constant temperature annealing of irradiated MOS samples has indicated that the annealed charge is linearly dependent on the logarithm of elapsed time over a finite time interval. This is particularly evident at room temperature where a linear dependence on In ( t ) has been observed out to 105seconds. Such a time dependence of released charge can result either from thermal activation of trapped carriers from a uniform trap distribution or from thermal emission of recombination electrons over a Schottky barrier from the silicon into the oxide; however, both of these models predict the released charge to be a linear function of absolute temperature. A much stronger temperature dependence has been observed during these experiments.
TL;DR: In this article, a planar Gunn oscillators and Schottky barrier diodes are fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end.
Abstract: GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits. The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (>10/sup 6/ ohm /spl dot/ cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated circuits thus allows for improved microwave performance from the devices since parasitic are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end. The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 10/sup 18/ - 10/sup/15/ - 10/sup 18/ cm/sup -3/. The Schottky diodes consist of two deposits with concentrations of 10/sup 18/ and 10/sup 17/ cm /sup -3/. The Schottky contact is formed by evaporating Mo-Au onto the 10/sup 17/cm/sup -3/ deposits; all ohmic contacts are on the surface and are alloyed to the N/sup +/ regions.
01 Jan 1968
TL;DR: A new high-speed low-power logic circuit using Schottky barrier diodes to avoid saturation of bipolar transistors is described and the possibility of subnanosecond logic using a saturated-type transistor logic circuit is shown.
Abstract: A new high-speed low-power logic circuit using Schottky barrier diodes to avoid saturation of bipolar transistors is described. An experiment using discrete devices and a theoretical calculation show the possibility of subnanosecond logic using a saturated-type transistor logic circuit. A theoretical comparison with CML shows a 2:1 advantage in the speed-power product. The compatibility of Schottky barrier diode with monolithic silicon integrated circuit processing is shown. A prototype TTL circuit is described. Experimental results are given.
TL;DR: In this paper, a planar gallium arsenide Schottky-barrier junction was constructed by the interface between a low-temperature, solid-solid, palladium-silicon reaction product and a very thin (∼ 0.5 μm) low-resistivity epitaxial silicon layer.
Abstract: Silicon Schottky-barrier junctions useful as down-converter diodes in the 5–6 mm-wavelength region have been fabricated by planar techniques. The rectifying junctions were formed by the interface between a low-temperature, solid-solid, palladium-silicon reaction product and a very thin (∼ 0.5 μm) low-resistivity epitaxial silicon layer. The junctions were 4 μm in dia. and were about 0.25 μm below the surface of the epitaxial layer. Zero-bias cutoff frequencies were in the range of 500–800 GHz. When mounted in suitable millimeter-waveguide down-converter circuits, the minimum measured conversion loss (51.7-1.3 GHz) was about 6.5 dB, and the minimum value of the product (conversion loss) times (noise temperature ratio) was about 7.5 dB. These values are at least 1 dB worse than values of the same quantities obtained by the use of millimeter-wave planar gallium arsenide Schottky-barrier diodes in the same circuits.
IBM1
TL;DR: Schottky-barrier field effect transistors have been realized in silicon epitaxial films on high-resistivity silicon substrates as mentioned in this paper, and the 1 μm wide gates are produced by projection masking techniques.
Abstract: Schottky-barrier field-effect transistors have been realised in silicon epitaxial films on high-resistivity silicon substrates. The 1 μm wide gates are produced by projection-masking techniques. The maximum transconductances observed are 42 mA/V per mm gate length; the maximum frequency of oscillation fmax was 8 GHz.
TL;DR: In this article, a planar Gunn oscillators and Schottky barrier diodes are fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end.
Abstract: GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits. The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (>106ohm.cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated-circuits thus allows for improved microwave pedormance from the devices since parasitics are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end. The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 1018-1015-1018cm-3. The Schottky diodes consist of two deposits with concentrations of 1018and 1017cm-3. The Schottky contact is formed by evaporating Mo-Au onto the 1017cm-3deposits; all ohmic contacts are on the surface and are alloyed to the N+regions.
TL;DR: In this paper, thin films of gold-silver alloy on n-type silicon were prepared by vacuum deposition of the alloy and the characteristics of the contacts were investigated by means of V-I and C-V measurements.
Abstract: Thin films of gold-silver alloy on n-type silicon were prepared by vacuum deposition of the alloy. The characteristics of the contacts were investigated by means of V-I and C-V measurements. The results showed that the barrier height of Au–Ag alloy–Si contacts varies linearly, from 0.67±0.02 eV to 0.80±0.02 eV, with composition of the alloy film. This is interpreted in terms of the change in work function which is linearly dependent upon the composition.
TL;DR: In this article, a forward-biased Schottky barrier with a thin layer of platinum on n-type conducting ZnS with the outer surface of the platinum cesiated to reduce its work function was demonstrated experimentally.
Abstract: Emission of electrons into vacuum from a forward‐biased Schottky barrier has been demonstrated experimentally. The emitting contact is a thin layer of platinum on n‐type conducting ZnS with the outer surface of the platinum cesiated to reduce its work function. Capacitance and photoemission measurements indicate that the ZnS:Pt barrier height is 2.3 eV. Under forward‐bias emission is observed.
Patent•
05 Jul 1968TL;DR: In this paper, a solid-state atomic particle and X-ray detector comprising an N-type semiconductor crystal of high atomic number, coated with a metallic film of low atomic number is presented.
Abstract: A solid-state atomic particle and X-ray detector comprising an N-type semiconductor crystal of high atomic number, coated with a metallic film of low atomic number. By making the metal-tosemiconductor interface abrupt, a Schottky barrier-type junction is produced. Atomic particles or X-rays can easily penetrate the metallic film but are absorbed in the semiconductor near the interface, producing electron-hole pairs in the depletion region. Holes which diffuse beyond the depletion region give rise to a current indicative of detection of X-rays or atomic particles.
TL;DR: GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits, and this monolithic approach to integrated circuits thus allows for improved microwave performance from the devices since parasitics are reduced to a minimum.
Abstract: GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits.The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (> 10 /sup 6/ ohm cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated circuits thus allows for improved microwave performance from the devices since parasitics are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94GHz) receiving front end.The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 10 /sup 18/ -10 /sup 15/ -10 /sup 18/ cm /sup -3/.The Schottky diodes consist of two deposits with concentrations of 10 /sup 18/ and 10 /sup 17/ cm /sup -3/.The Schottky contact is formed by evaporating Mo-Au onto the 10 /sup 17/ cm /sup -3/ deposits; all ohmic contacts are on the surface and are alloyed to the N+ regions.
TL;DR: The behavior of gallium arsenide Gunn oscillators, transistors, Schottky barrier diodes and optoelectronic pulse amplifier, were investigated in a flash X-ray environment as discussed by the authors.
Abstract: The behavior of gallium arsenide Gunn oscillators, transistors, Schottky barrier diodes and optoelectronic pulse amplifier, were investigated in a flash X-ray environment. The damaging effects of fast neutrons from a pulsed reactor were also observed. When possible, the resultant data were compared with available data for similar silicon devices.
TL;DR: The construction of Au-GaAs Schottky diodes with forward current/voltage characteristics linearly exponential over more than eight decades of current was described in this paper.
Abstract: The construction of Au-GaAs Schottky diodes with forward current/voltage characteristics linearly exponential over more than eight decades of current is described. The characteristics of these diodes are shown to depend in part on the temperature used for bonding the contacts.
TL;DR: In this paper, the application of ion implantation to the fabrication of Au-Si Schottky diodes with highly nonlinear capacitance/voltage characteristics is described.
Abstract: The application of ion implantation to the fabrication of Au-Si Schottky diodes with highly nonlinear capacitance/voltage characteristics is described. The capacitance/voltage characteristic and the derived impurity profile are given for a typical diode. The forward current/voltage characteristics are described, and an estimate of Au-Si barrier height is made.
TL;DR: The threshold current density of an electron-beam pumped GaAs laser is sensitively dependent upon the profile of the electron beam and the beam voltage as discussed by the authors, and the peak of the distribution of minority carriers is of the order of one diffusion length from the surface, suggesting that nonradiative surface recombination plays an important role.
Abstract: The threshold current density of an electron-beam pumped GaAs laser is sensitively dependent upon the profile of the electron beam. Minimum power threshold current density is obtained with the excitation far above threshold value at the center of the Fabry-Perot cavity and with vanishingly small values at the ends. Threshold current density is also dependent upon beam voltage. For voltages of the order of 30 kV, the peak of the distribution of minority carriers (including the effects of diffusion and surface recombination) is of the order of one diffusion length from the surface, suggesting that nonradiative surface recombination plays an important role. This has been confirmed by measurements on samples with a Schottky barrier. Threshold current density of n -type GaAs at 77°K (40-mil Fabry-Perot cavity, 30-kV beam voltage) decreases from 0.69 A/cm2at 4 \times 10^{17} /cm3to 0.44 A/cm2at 4 \times 10^{18} /cm3. Power output over the same doping range peaks at about 2 \times 10^{18} /cm3with 20 watts obtained at an overall efficiency of 2.5 percent. Peak differential external quantum efficiency of the order of 30 percent occurs at about the same doping density. Using Hunsperger and Ballantyne's values of α, we deduce that the internal quantum efficiency may be as high as 90 percent.
Patent•
26 Dec 1968TL;DR: In this article, a Schottky barrier or hot carrier diode is constructed by diffusing an impurity through an opening in a diffusion mask and into one surface of the semiconductor body to form PN junction.
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.
Patent•
03 Jul 1968TL;DR: In this article, the Schottky barrier was used to charge the rectifying junctions of a solid-state light-sensitive storage device, where an electron beam is scanned over a surface upon which the metal spots are formed to reverse bias and capacitively charge the capacitive junctions, and the current required to recharge each capacitor as the electron beam was scanned produces an output voltage across a load resistance.
Abstract: An electronic camera utilizing a solid-state light sensitive storage device comprised of a sheet of semiconductor material having a large number of very small electrically isolated metal spots on one surface of the sheet each forming a rectifying, capacitive junction of the type referred to as a Schottky barrier. An electron beam is scanned over a surface upon which the metal spots are formed to reverse bias and capacitively charge the rectifying junctions. A light image focused on the other side of the semiconductor slice discharges each discrete capacitor in proportion to the intensity of the light at the location of said discrete capacitor. The current required to recharge each capacitor as the electron beam is scanned produces an output voltage across a load resistance. The light sensitive storage device is fabricated by properly preparing the surface of the substrate and then evaporatively depositing a layer of the metal, e.g. platinum or gold, at a temperature such that the metal nucleates to form a very thin, discontinuous film having discrete electrically isolated microscopic globules.