Showing papers on "Schottky diode published in 1975"

Admittance spectroscopy of impurity levels in Schottky barriers

Abstract: Measurements of the complex admittance of Schottky‐barrier diodes as a function of temperature provide a spectroscopy of deep trapping levels. The measurement conditions are usually close to thermal equilibrium, thus assuring the validity of equilibrium occupation probabilities. An exact (i.e., to arbitrary accuracy) solution for the junction admittance is given. The problem is reduced to solution of a simple initial‐value problem, the final integration being carried out by computer. It is shown that the dispersion in capacitance due to slow trapping levels can lead to serious errors in estimates of junction doping concentrations and barrier height determinations. Examples are given for p‐type ZnTe where Shockley‐Read‐Hall (SRH) centers are dominant and for n‐type CdTe and Cd1−xZnTe where double‐acceptor centers are dominant. For junctions formed on CdTe : Ga it is shown that one of the steps in capacitance observed in a thermally stimulated capacitance survey is actually a high‐frequency response step an...

Conductance and capacitance studies in GaP Schottky barriers

Abstract: A study of the conductance and capacitance associated with traps in Schottky barriers is described. A sample calculation of these two quantities is developed and compared with experimental data obtained in GaP VPE saples. It is shown that traps introduce peaks on the conductance‐vs‐temperatures curves; from them the concentration of each trap can be calculated. A study at different frequencies permits the determination of the characteristics of the traps. In GaP we have observed trapping effects in donor levels at Ec−Et?100 and 86 meV, the emission rates were found, respectively, to equal 2×1011 and 2×109 s−1 for these two levels. It is also shown that photoconductance effects occur at the oxygen deep levels.

Low-Noise Room-Temperature and Cryogenic Mixers for 80-120 GHz

Abstract: A description is given of two new mixers designed to operate in the 80-120-GHz range on the 36-ft radio telescope at Kitt Peak, Ariz. It is shown that for a hard-driven diode the parasitic resistance and capacitance are the primary factors influencing the design of the diode mount. A room-temperature mixer is described which achieves a single-sideband (SSB) conversion loss (L) of 5.5 dB, and a SSB noise temperature (T/sub m/) of 500 K (excluding the IF contribution) with a 1.4-GHz IF. A cryogenically cooled version, using a quartz structure to support the diode chip and contact whisker, achieves values of L = 5.8 dB and T/sub m/ = 300 K with a 4.75-GHz IF. The mixers use high-quality Schottky-barrier diodes in a one-quarter-height waveguide mount.

InP Schottky-gate field-effect transistors

Abstract: MESFET's with gates 1 µm long were fabricated in LPE layers of InP on Cr-doped InP substrates. The quality of the LPE material is characterized by an electron concentration of 4 × 1015cm-3with a mobility of 2.6 × 104cm2V-1s-1at 77 K for growths from undoped melts. The devices have current gain cutoff frequencies of 20 GHZ or somewhat larger. This value is greater than that of the best analogous GaAs MESFET bya factor of 1.5. A factor of 1.3 is predicted on the basis of a simple theory. The highest power gain cutoff frequency, f max , for the InP device is 33 GHz which is somewhat smaller than that of the best analogous GaAs device. The lowest minimum noise figure at 10 GHz for these first InP devices is 3.9 dB with an associated gain of 4.8 dB. The best result for the GaAs counterpart is 3.2 dB with an associated gain of 7.8 dB. The power gain of the InP device suffers compared to the GaAs device because of degenerative feedback resulting from a large gate-to-drain capacitance and because of a small output resistance. If the magnitudes of these two equivalent circuit elements were the same for MESFET's in the two materials, f max for the InP device would be more than double its present value.

Design and performance of X-band oscillators with GaAs Schottky-gate field-effect transistors

Abstract: The circuit construction and design of an X-band oscillator with a GaAs Schottky-gate FET have been studied. The oscillation characteristics including stability and noise performance have been examined in order to clarify the position of a GaAs FET as a microwave solid-state oscillator device. The experiments have revealed that 1) the GaAs FET simultaneously possesses the most desirable features of both Gunn and IMPATT oscillators, i.e., low bias voltage operation and fairly high efficiency, and 2) it is situated between Gunn and GaAs IMPATT oscillators with respect to noise properties. The results indicate that the GaAs FET oscillator will soon be joining the family of microwave solid-state oscillators as a promising new member.

Determination of the density and the relaxation time of silicon-metal interfacial states

Abstract: In this article a method is described for the determination of the density and the relaxation time of the Si-metal interfacial states from measurements of the admittance of a forward biased Schottky diode.

The Conductivity of Crystalline NaI

Abstract: The d.c. conductivity of NaI has been measured in the intrinsic and extrinsic temperature regions. The formation energy Es for the Schottky defects and the energy Em+ for the cation vacancy migrati...

A Schottky‐diode acoustic memory and correlator

Abstract: Experiments demonstrate that images of acoustic signals can be stored for tens of msec in a matrix of Schottky diodes on a silicon surface adjacent to a lithium niobate surface‐wave delay line. The experiments show charging times of the order of 10 nsec.

Temperature effects in Schottky-barrier silicon solar cells

Abstract: Experimental results are reported concerning temperature effects from 25 to 125 °C on Schottky‐barrier solar cells which were fabricated using a semitransparent Cu/Cr barrier metal layer on p‐type silicon. The open‐circuit voltage decreased by 2.3 mV/°C and the fill factor by 0.11%/°C, while the short‐circuit current increased slightly with increased temperature. These results are consistent with previous work on p‐n–junction silicon solar cells. The diode quality factor n was shown to decrease with increased temperature, as predicted by field emission theory. The room‐temperature photovoltaic output of cell 96 remained at 0.54 V, 25.4 mA/cm2, and 8.5–10.6% efficiency using 80–100‐mW/cm2 sunlight illumination after repeated temperature cycling.

Deep-level controlled lifetime and luminescence efficiency in GaP

Abstract: The influence of deep levels on the minority‐carrier lifetime and relative cathodoluminescent efficiency of undoped GaP has been investigated. Evidence that both these parameters are deep‐level controlled is presented. The dominant center was detected by thermal capture and emission of minority carriers optically injected into the depletion layer of Schottky barriers. This center was found to have a depth of ET−EV=0.75 eV and a hole capture cross section of approximately 4×10−14 cm2.

GaAs dual-gate Schottky-barrier FET's for microwave frequencies

Abstract: The benefits inherent in the tetrode structure and the potential of GaAs are combined to realized a dual-gate FET with low noise and a wide dynamic range at microwave frequencies. A design theory of the dual-gate FET is constructed on the basis of the Lehovec-Zuleeg model for single-gate FET's. The theory has led to a new device structure having a second gate with a deeper pinchoff voltage than the first which shows improved gain and noise performance. Also derived is the importance of minimizing parasitic feedthrough due, for example, to packages. Samples were fabricated using n-type epitaxial GaAs. The first and second gates were Schottky barriers, 1.2 and 2.5 µm long. The improved channel structure was accomplished by reducing the thickness of the epitaxial layer under the first gate. Samples were mounted and characterized in specially designed small-size ceramic packages with a feedthrough capacitance of only 0.004 pF. The possibility of gain control by means of second gate bias over a wide bandwidth is demonstrated.

Investigation of defects and striations in as‐grown Si crystals by SEM using Schottky diodes

Abstract: As‐grown silicon crystals are investigated in the scanning electron microscope using Schottky barrier diodes in the electron‐beam‐induced current mode. Dislocations, A‐ and B‐type swirl defects, as well as dopant striations are detected. In high‐resistivity crystals (∼1000 Ω cm) variations in dopant concentration of 1012 cm−3 are readily revealed. Hydrogen doping is found to eliminate preferential recombination at microdefects. It is established that bulk stresses due to carbon striations have no detectable electrical effect.

Modeling and Computer Simulation of a Microwave-to-DC Energy Conversion Element

Abstract: A microwave-to-dc energv conversion element consisting of a dipole antenna, a low-pass filter, a Schottky-barrier diode, and a dc filter has been modeled using a distributed transmission-line modeling technique that includes skin-effect losses. Computer simulation has shown 80-percent conversion efficiency and has indicated that the diode generates significant power at higher harmonics due to a resonance effect.

Schottky I/sup 2/L

Abstract: Schottky I/SUP 2/L uses the principles of integrated injection logic (I/SUP 2/L/MTL) and the properties of ion implantation to obtain improved performance at the same densities as conventional I/SUP 2/L. Schottky diodes are formed in the multicollectors of the switching transistor and reduce the signal swing, thus improving the power delay efficiency. An increase in the intrinsic speed limit is also feasible. The Schottky I/SUP 2/L structure and characteristics are described and contrasted with conventional I/SUP 2/L. A model which is useful for its design is discussed. Integrated test structures which provide direct comparison between conventional and Schottky I/SUP 2/L performance have been fabricated. The experimental results demonstrate a factor of 2 improvement in power-delay efficiency of Schottky I/SUP 2/L over conventional I/SUP 2/L.

Enhancement of Schottky solar cell efficiency above its semiempirical limit

Abstract: Geometries are described for increasing the efficiency of Schottky solar cells above the theoretical limits recently calculated. The ultimate conversion efficiencies for the new cells are the same as for p‐n junction devices. With present technology, improvements of over 50% above the old limits are possible.

Photoemission study of the formation of Schottky barriers

Abstract: For the first time, changes in electronic structure have been studied during Schottky barrier (Cs on GaAs or InP) formation. Strong changes occur near the valence band maximum; however, these do not overcome a dominant role of intrinsic surface states in Fermi‐level pinning.

Thin-phase epitaxy for good semiconductor metal ohmic contacts

Abstract: Ohmic contacts of superior quality are produced by treating the normal alloying process as an epitaxy process, where Ga and As are supplied separately by evaporation together with the normal contact metals and by overpressure, respectively. New device fabrication methods based on this new scheme are the production of shallow p-n junctions, shallow heterojunctions, thin ternary semiconductor layers with different bandgaps from that of the bulk, and multiple structures. By using photoresist, complete regrowth patterns as used for IC's should be possible. The types of devices where these developments should be of interest are solar cells, light-emitting IC patterns, even with different light colors on one chip, Gunn devices, BARITT's, MESFET's, Schottky CCD's, heterojunction bipolar transistors, etc.

Electroluminescence in zinc selenide

Abstract: The electroluminescent properties of Schottky diodes formed from single cyrstals of zinc selenide containing manganese, manganese and aluminium, aluminium or chlorine are discussed. All such diodes emitted a yellow band of variable width in reverse bias, the maximum of which lay between wavelengths of 5785 (2·14 eV) and 6050 A (2·05 eV). Optimum emission was obtained from ZnSe:Mn diodes where luminances of 500 ft L were achieved at a power efficiency of 1·9 × 10−3%. Maximum efficiency of 3 × 10−3% was obtained at a slightly lower luminance of 300 ft L. The ZnSe:Mn diodes exhibited the characteristic manganese emission in reverse bias in a narrow band centred at 5785 A (2·14 eV). The presence of foreign donors such as aluminium reduced the luminance and the efficiency. This, coupled with a slight shift of the emission to longer wavelengths and a broadening of the emission band, is associated with the onset of the excitation of the self-activated emission which increased with increasing donor content. The self-activated emission in electroluminescence was found at 6300 A (1·97 eV) in ZnSe:Al and at 5900 A, (2·1 eV) in ZnSe:Cl. Forward bias electroluminescence was only observed in diodes which contained a relatively thick (∼200 A) insulating layer under the Schottky contact. Forward electroluminescence was at least an order of magnitude less bright than reverse EL.

Gunn device gigabit rate digital microcircuits

Abstract: Monolithic integration of planar Gunn devices on GaAs is a very promising method to realize microcircuits for the Gbit/s range. Semiinsulating GaAs is readily available as substrate material. In this paper estimates of characteristic parameters of these circuits, such as maximum pulse rate, power consumption, and package density, are presented. Three different methods of domain control are available: a) by separate Schottky barrier diode; b) by MESFET; or c) by Schottky barrier gate on the channel of the Gunn device. Theoretical limits for these methods are given. Maximum pulse rates of 11, 5, and 7 Gbit/s, respectively, can be expected. Unidirectionality and trigger drive of the three methods are rated. Experimental integrated circuits were built to demonstrate the capability of the methods of domain control. Comparison with calculations yields good agreement. Coming close to the theoretical limits has not yet been accomplished in all practical cases since further miniaturization of the circuits and improvement of the material properties relevant to domain processes is needed. After progress in these two points it is expected that the theoretical limits will be reached.

Submillimeter detection using a Schottky diode with a long‐wire antenna

Abstract: A Schottky diode originally made for use as a detector and a mixer in the millimeter‐waveglength region has been used as a room‐temperature fast detector in the submillimeter‐wavelength region. A voltage responsivity of 2 V/W and an NEP of 1×10−7 W/Hz1/2 at 337 μm were obtained by using high‐gain long‐wire‐antenna coupling. The experimental and theoretical responses of the antenna structure are compared.

I-V characteristics for Silicon Schottky solar cells

Abstract: A special-layered Schottky solar cell has been constructed which produces 95-percent sunlight efficiency over a 1-cm2area This solar cell has a fill factor of 060 compared to 058 for a commercial p-n silicon cell Series resistance of 5 Ω is shown to reduce the theoretical fill factor from 067 to 042 for a Schottky cell The diode quality factor n is shown to significantly increase open-circuit voltage and yet not appreciably influence the fill factor

Effects of thermal excitation and quantum-mechanical transmission on photothreshold determination of Schottky barrier height

Abstract: Quantum-mechanical electron transmission effects on photothreshold determination in Schottky barriers with high electric fields are shown to produce a strong effect on apparent photothresholds without a concomitant large change in shape of the photoresponse curve. Quantum-mechanical electron transmission probabilities are determined by numerical integration of the Schroedinger equation for a Schottky barrier model which includes Thomas-Fermi shielding in the metal, image force lowering in the semiconductor, and conservation of transverse momentum at the metal-semiconductor interface. Results are presented for n -type Si and n -type GaAs. In the case of Si, conservation of transverse momentum at the interface produces a discontinuity in the electron kinetic energy associated with motion normal to the interface but does not greatly affect the transmission probability. Using these results, the difference between the true barrier height, qΦ B , and the apparent barrier height, qΦ A , is calculated as a function of temperature, doping, and electric field at the metal-semiconductor interface. qΦ A is defined as the intercept on the hv axis of the slope of a plot of (photocurrent per absorbed photon) 1 2 versus quantum energy, hv . Effects of barrier curvature due to doping are negligible for impurity densities below about 10 18 cm −3 for Si and 10 17 cm −3 for GaAs. Values of q ( Φ B - Φ A ) in excess of 50 meV occur in many cases. The corrections derived are used to reinterpret previously reported measurements of the dependence of Schottky barrier height on temperature and impurity concentration.

Schottky diode - complementary transistor logic

Abstract: A logic circuit uses an input Schottky diode of a first threshold and a clamp Schottky diode of a second threshold in combination with a high speed NPN switching transistor to form a simple high speed logic element. The novel use of two Schottky diodes of different threshold voltages provides a logic gate with a lower logic swing amenable with higher speed operation. Further, the operation of the logic gate is independent of the temperature characteristics of the NPN switching transistor. A PNP current source provides the drive current and load current for the logic gate in a simple manner which uses minimum chip area.

Circuit model for the GaAs m.e.s.f.e.t. valid to 12 GHz

Abstract: A new equivalent circuit is given for the GaAs m.e.s.f.e.t., which includes resistive loss in the feed back elements. The circuit values are given for several 1 μm-gate GaAs m.e.s.f.e.t.s. A method for fitting s12 to the measured data is described. Finally, the gain and stability factor of several GaAs m.e.s.f.e.t.s. are extrapolated to 24 GHz from the present model.

InP microwave oscillations with 2-zone cathodes

Abstract: A 2-zone cathode comprising a thin n+ region under a high-resistance contact improves the efficiency on transferred-electron oscillators. InP devices have shown high efficiency over a temperature range of -50 to +150°C.

Metallization scheme for n−GaAs Schottky diodes incorporating sintered contacts and a W diffusion barrier

Abstract: Using Schottky barrier measurements on n−GaAs diodes metallized with Au/W and Pt/W films, we have shown that thin films of W (∼3000 A) offer an excellent barrier to diffusion of both Au and Pt atoms at temperatures up to 500 °C. These properties of W are utilized in a Schottky barrier metallization scheme consisting of Au/W/(PtGa/PtAs2)/n−GaAs, where (a) the thin sintered Pt layer provides a large φB (due to PtAs2 at the GaAs interface) and a metallurgically stable conductor−semiconductor interface, (b) the W layer acts as a diffusion barrier, and (c) the outer Au layer provides thermocompression bondability.

Photoemission measurements of filled and empty surface states on semiconductors and their relation to schottky barriers

Abstract: (1975). Photoemission measurements of filled and empty surface states on semiconductors and their relation to schottky barriers. C R C Critical Reviews in Solid State Sciences: Vol. 5, No. 3, pp. 245-258.