Showing papers on "Schottky barrier published in 1973"

Schottky barrier height of n‐InxGa1−xAs diodes

Abstract: The barrier heights φB of Au/n‐InxGa1−xAs diodes are measured by the capacitance‐voltage and saturation current methods. The composition dependence of the barrier height is φB (eV) = 0.95 − 1.90x + 0.90x2. A low barrier height with a relatively wide band gap is obtained in this system.

Use of a Schottky barrier to measure impact ionization coefficients in semiconductors

Abstract: The use of a Schottky barrier to determine the impact ionization coefficients of electrons and holes in semiconductors has been studied analytically and also evaluated experimentally by comparing the results for silicon with those already available in the literature. The Schottky barrier offers several advantages over a diffused p-n junction in such measurements. Pure electron initiation and pure hole initiation can be separately achieved. The abrupt barrier provides an accurately known electric field, and the linearity of the field distribution simplifies the problem of extracting the ionization coefficients from the multiplication data. We present a general solution of the charge multiplication equation and derive expressions for the ionization coefficients for the particularly simple conditions that can be achieved in a Schottky-barrier junction. Our results for silicon in the range 2 × 105 α = α ∞ exp ( −b n E ) for electrons and β = β ∞ exp ( −b p E ) for holes, with α∞ = 9·2 × 105 cm−1, β∞ = 2·4 × 105 cm−1, bn = 1·45 × 106 V/cm and bb = 1·64 × 106 V/cm.

The C-V characteristics of Schottky barriers on laboratory grown semiconducting diamonds

Abstract: Measurements of the differential capacitance of evaporated gold Schottky barriers on laboratory-grown, boron-doped semiconducting diamonds have been obtained for the first time as functions of reverse-bias voltage, frequency, and temperature The data are analyzed on the basis of a model which includes the effects of long time constants for hole capture from the deep (boron) level, as well as previously unobserved effects due to the series resistance of the bulk The barrier height at 300°K is found to be 1·73 ± 1·10 eV , in good agreement with the ‘one-third band gap’ value of Mead and Spitzer Excellent correlation is found between optical transmission measurements and the C-V analysis for the uncompensated boron concentration, indicating that all of the optically observable dopant is electrically active By fitting the model with two adjustable parameters at room temperature, good agreement is obtained between measured and calculated capacitance over two and a half decades as a function of temperature The analysis indicates that the activation energy of the acceptor level is 0·26–0·37 eV for the samples studied, while the associated capture cross-sections are 0·9–2·0 × 10 −17 cm 2

Minority carrier effects upon the small signal and steady-state properties of Schottky diodes

Abstract: Schottky diode theory is re-evaluated by applying the combined thermionic emission-diffusion theory to both the majority and minority carrier flows across the metal-semiconductor contact. Under both steady-state d.c. and small signal a.c. conditions, numerical solutions to the semiconductor transport equations subject to boundary conditions determined from the combined theory are used to investigate the effects of minority carriers upon the properties of uniformly doped Schottky diodes. High injection effects and contact limitations are shown to influence the minority carrier injection ratio and the total stored minority carrier charge. It is further shown that the small signal impedance of a large class of Schottky diodes becomes inductive under moderate forward bias.

Schottky-barrier capacitance measurements for deep level impurity determination

Abstract: The time dependence of a Schottky-barrier capacitance due to thermal excitation of trapping centres has been studied. An expression for the junction capacitance is derived which is not restricted to any special range of reverse bias nor to a special relation between shallow and deep impurity concentration. The concentration ratio of shallow to deep centres is calculated from the values of the capacitance at zero and infinite time. From a capacitance vs. time plot the trap emission rate for electrons e n is obtained. Their energetic level within the forbidden band-gap is determined from the temperature dependence of e n as well as from the capacitance-time variation. Experimental studies which do confirm the calculations were carried out on gold contacts on oxygen-doped n -type GaAs. Representative results of the investigated samples were: shallow donor density 3 × 10 15 cm −3 , trap density 9·8 × 10 15 cm −3 , electron emission rate 6 × 10 −2 sec −1 , energetic level 0·68 eV and capture cross section 7 × 10 −16 cm 2 .

Unified theory of high‐frequency noise in Schottky barriers

Abstract: A unified noise‐temperature equation is presented which describes the high‐frequency noise (>1/f noise) characteristic of Schottky barrier diodes from above room temperature to cryogenic temperatures. The unified noise equation takes into consideration the dominant transport mechanism of the barrier and is applicable to any metal‐semiconductor system. Noise‐temperature measurements on fabricated Schottky barrier diodes at 18, 77, and 300 °K confirm the validity of the noise theory presented.

Metal-germanium Schottky barriers

Abstract: A systematic study has been made of the electrical characteristics of Schottky barriers fabricated by evaporating various metal films on n -type chemically cleaned germanium substrates. The diodes, with the exception of AlGe contacts, exhibit near-ideal electrical characteristics and age only slightly towards lower barrier height values. AlGe contacts exhibit very pronounced ageing towards higher barrier height values, due to formation of an extra aluminium oxide interfacial layer. Because of this, the barrier height values of aged AlGe contacts derived from I - V and C - V characteristics differ significantly. The dependence of the barrier height, ( φ b ) on the metal work function, φ m , for different metal-germanium contacts shows that surface states play an important role in the formation of the barrier. The density of germanium surface states is estimated to be D s = 2 × 10 13 eV −1 cm −2 .

Photoconductive gain greater than unity in CdSe films with Schottky barriers at the contacts

Abstract: Photoconductive gains greater than unity can be obtained by illuminating a homogeneous photoconductor having blocking contacts with band gap radiation. A model is presented, which conceives such a possibility. Au contacts to CdSe form a Schottky barrier at the interface. Upon illumination the photogenerated holes are trapped in the Schottky barrier, shrinking the barrier and allowing injection of electrons in the CdSe. This gives rise to the possibility of gain greater than unity. Experimental evidence supporting the model is presented. Photoconductive gains as large as 300 have been measured when these films were illuminated with a photon flux of 2×1015 photons/cm2/sec.

Capacitive effects of Au and Cu impurity levels in Pt-N type Si Schottky barriers

Abstract: Au and Cu impurity effects on the capacitance-voltage ( C – V ) relationship of Pt- n type Si Schottky barrier diodes have been investigated over the frequency range of 100 Hz to 500 kHz at 200°K and 300°K. The barrier height of the Pt-Si system measured by C – V , I – V , and photothreshold techniques was 0.83±0.01 eV. Deep level C – V effects previously predicted by Roberts and Crowell were observed. Diodes on phosphorus-doped Si nearly compensated with Au clearly exhibited a non-monotonic low frequency C – V relationship. An inflection point in the C −2 - V curve attributable to the Au donor level 0.77 eV from the conduction band edge was observed. The experimental data show that the presence of deep levels makes barrier height measurements appreciably ambiguous and that impurity profiles determined from a C – V relationship using a model which neglects their presence can be shifted appreciably both in apparent magnitude and apparent position.

The superconductor‐semiconductor Schottky barrier diode detector

Abstract: The superconductor‐semiconductor contact diode, or super‐Schottky‐barrier‐diode, has been examined theoretically and experimentally as a video detector of high‐frequency radiation. The measured noise‐equivalent power (NEP) of the device is believed to be the smallest value ever reported in the literature for video detection. Moreover, the high reliability established for the ordinary Schottky barrier diode is in evidence for the proposed diode. The doping of the semiconductor is chosen large enough so that electron tunneling dominates the volt‐ampere behavior of the diode. As such, for T < Tc and V < Δ, the diode exhibits a high degree of nonlinearity in its volt‐ampere characteristic. It is this nonlinearity that the super‐Schottky‐diode exploits. Initial results with p‐type GaAs at 1 °K have yielded an NEP of 2 × 10−15 W/Hz1/2 at 10 GHz.

Si and GaAs 0.5 μm-gate Schottky-barrier field-effect transistors

Abstract: Si and GaAs Schottky-barrier field-effect transistors with gate lengths of 0.5 μm have been experimentally realised. Noise and gain properties were measured in the microwave range up to 20 GHz. When compared with 1 μm-gate f.e.t.s, the devices show considerable improvements in gain and in noise figure. At 10 GHz, the following values were measured: Si m.e.s.f.e.t.: maximum available gain = 5.9 dB, noise figure = 5.8 dB; GaAs m.e.s.f.e.t.: maximum available gain = 12.8 dB, noise figure = 3.7 dB.

Determination of deep‐level energy and density profiles in inhomogeneous semiconductors

Abstract: A method is proposed for the determination of deep impurity levels and density profiles from C–V measurements and is demonstrated on GaAs Schottky barrier diodes. The technique involves measurements of the time dependence of the bias voltage instead of the barrier capacitance. The spatial distribution of a deep level is observed to exhibit a peak at the boundary between an epitaxial layer and the semi‐insulating substrate. This deep center is located 0.8 eV below the conduction band.

Tantalum-gallium arsenide schottky barrier semiconductor device

Abstract: A schottky barrier semiconductor device wherein the semiconductor is gallium arsenide and the metal electrode is tantalum, passivated by formation of native oxides after the metal-semiconductor junction is made Tantalum acts as a diffusion shield, enabling use of gold as a direct contact on the electrode

Proton-implanted optical waveguide detectors in GaAs

Abstract: Defect levels introduced by implanting GaAs with high-energy protons give rise to optical absorption at wavelengths greater than that of the normal absorption edge at 0.9 µ. Optical waveguide detectors may be fabricated by taking advantage of this absorption mechanism in the presence of a Schottky barrier depletion layer. Detector response times less than 200 ns and external quantum efficiencies of 16% have been observed.

Gallium arsenide schottky barrier avalance diode array

Abstract: Gallium arsenide power dissipating devices are described, which comprise an array of mesas formed on a plated heat sink in order to reduce thermal effects. The array is connected in parallel with beam leads to permit thermocompression bonding to only one of the mesas and thus reduce the number of bonding operations. Bonding stresses to the device may be eliminated by rendering one of the mesas inactive.

Bias-dependent phase delay of Schottky contact microstrip line

Abstract: Schottky contact lines are a form of microstrip on a semiconducting substrate, the strip of which forms a rectifying metal–semiconductor contact. Such a line has an extremely low phase velocity that is determined by the ratio of the depletion-region width to the substrate thickness, i.e. by the bias. Measurements agree well with theoretical expressions that are deduced from a parallel-plate-waveguide model.

Schottky barrier diode semiconductor structure and method

Abstract: Schottky barrier diode semiconductor structure having a semiconductor body formed essentially of silicon and having a surface with an active device formed in the semiconductor body having collector, base and emitter regions and with at least two metals on said surface combining with the silicon to form an alloy of at least two metals and silicon which is in contact with the collector, base and emitter regions and also extends beyond the base region to form a Schottky barrier diode having a barrier height which is determined by the composition of the alloy. In the method, the alloy of at least the two metals in combination with the silicon is adjusted to modify the barrier height of the Schottky barrier diode so that a barrier height can be chosen ranging from between 0.64 and 0.835.

Solid state radiation detector and process

Abstract: A radiation detector that combines the characteristics of high quantum efficiency in the UV spectrum with good IR transmission characteristics so that it may be used in association with an IR sensor to produce a coaxial transducer suitable for use in association with unfiltered, high-resolution optics. The detector is a solid state photovoltaic Schottky barrier semi-conductor junction comprising a thin platinum layer laid over single-crystal cadmium sulfide. Processing, including lapping, polishing, and chemical etch, produces a surface suitable for providing radiation sensitivity which drops off sharply outside of the ultraviolet spectrum beyond 550 nanometers. The platinum layer is approximately 35 angstroms in thickness and is therefore transparent both to ultraviolet and infrared radiation. The infrared radiation passes through the cadmium sulfide wafer and through a window in the indium ohmic contact surface on the second surface of the cadmium sulfide crystal. An infrared sensor positioned in association with this window will be exposed to up to 85% of the incident infrared radiation.

Application of facet-growth to self-aligned schottky barrier gate field effect transistors

Abstract: A semiconductor device and particularly a self-aligned Schottky barrier gate field-effect transistor is made by epitaxial growth of facets corresponding to the source and drain regions on a surface of a semiconductor body through spaced apart preferably elongated windows in a masking layer and overgrowing edge portions of the masking layer at the windows to form overgrown portions on the facets. The channel region of the transistor is previously formed in the semiconductor body, preferably by epitaxial growth of a layer on a surface of a semiconductor body having a semi-insulating layer adjoining the surface. After removal of the masking layer, the Schottky barrier gate is self-aligned by deposition of metal on the unshielded portions of the planar surface between the facets.

Manufacture of a high voltage Schottky barrier device

Abstract: Providing a substrate doped with a first type of impurity and having a silicon dioxide ring deposited thereon which is doped with a second type of impurity. Treating the substrate to diffuse the impurities from the ring into the substrate immediately therebelow to form a guardring aligned with the aperture through the silicon dioxide ring. Depositing barrier and contact metals within the aperture of the silicon dioxide ring to form a Schottky barrier aligned with said guardring.

Au - (n-type) InP Schottky barriers and their use in determining majority carrier concentrations in n-type InP

Abstract: The electrical characteristics of Au - (n-type) InP Schottky barriers fabricated on etched surfaces are reported. The barrier height of the junction is low (040 eV), and from this value of barrier height the surface state model of {110} etched InP is shown to be in line with the general picture for other III-V compounds. Measurements are also reported of n-type InP carrier concentration determination in the range 5×1015-4×1016 cm−3 using conventional Schottky barrier C-V analysis. For voltages greater than a few tenths of a volt reverse bias this procedure yields values of carrier concentration that are in good agreement with values determined by Hall measurements. Below this voltage the capacitance data are no longer representative of carrier concentration in the normal way due to the onset of incomplete depletion of mobile carriers in the barrier region.

Radiation sensing arrays

Abstract: A radiation sensing array includes two semiconductor layers of different conductivity types with a large area semiconductor junction therebetween. One of the layers is relatively thin and a substantially transparent metal layer located on the radiation receiving surface thereof forms a Schottky barrier therewith. Surface charge accumulation electrodes are coupled to the opposite surface of the body. The carriers generated at the Schottky barrier in response to a radiation image projected thereon travel through the junction and second layer and accumulate at the surface of the second layer as minoritycarrier, surface-charge signals.

Deep trap levels of ion‐implanted germanium in silicon measured by Schottky contact techniques

Abstract: Differential capacitance measurements on Schottky contacts can be used to determine energy level, charge, and concentration profile of ion‐implanted impurities which cause deep trap levels in the semiconducting material. For the example of germanium implanted into silicon, two deep donor levels at Ec − E 1 = 0.27 eV and E 2 − Ev = 0.51 eV are found which are due to an unstable incorporation of the implanted germanium in the silicon lattice. For the stable incorporation which is obtained at high annealing temperatures, no isoelectronic levels are found for germanium on lattice sites in silicon.

Advantages of Mott barrier mixer diodes

Abstract: It is shown that the high-frequency performance of miter diodes can be appreciably improved by employing a Mort barrier instead of a Schottky barrier. The larger junction diameters possible with Mott structures also allow a better burnout capability and improved mechanical stability.