Showing papers on "Schottky barrier published in 1969"

Isolation of junction devices in GaAs using proton bombardment

Abstract: Proton bombardment has been used to convert both p- and n-type GaAs into high resistivity material. It will be shown that this technique is useful for isolating junction devices and fabricating arrays. The average carrier concentration in the bombarded layer is less than 1011/cm3, and the layer thickness is about one micron for every 100 keV of proton energy. These layers are apparently unaffected by a 16 hr anneal at 300°, and only slightly affected at 400°. Using this technique, we have isolated islands of n-type GaAs on a semi-insulating substrate, separated p-n junctions on an n-type substrate, and suppressed edge breakdown in Au-GaAs Schottky barrier diodes.

Ohmic Contacts to Solution‐Grown Gallium Arsenide

Abstract: Carrier concentration profiles and surface resistance of Ohmic contacts to solution epitaxial n-type GaAs wafers measured by Schottky barrier capacitance

Richardson constant and tunneling effective mass for thermionic and thermionic-field emission in Schottky barrier diodes

Abstract: An appreciable difference is shown to be expected to exist between the experimentally measured Richardson constant and the ‘ideal’ Richardson constant associated with the flux of a Maxwellian distribution of carriers in a semiconductor. The equality which must exist between the Richardson constant for the forward and reverse characteristics is discussed. The semiconductor charge carrier energy—wave vector relationship rather than that of the metal is shown to be dominant because it controls the cone of acceptance for carriers incident on the barrier from the metal side. The effective mass in the ideal Richardson constant for T-F emission is shown to be the same as that for thermionic emission. This mass, which is associated with the E - k relationship transverse to the direction of current flow, can be considerably different from the tunneling effective mass which is the effective mass component in the direction of the current flow.

Surface State and Interface Effects on the Capacitance‐Voltage Relationship in Schottky Barriers

Abstract: In the presence of an interfacial layer and semiconductor surface states, a Schottky barrier height φb decreases with increasing electric field E at the surface of the semiconductor. If the semiconductor doping concentration Nd is uniform throughout the depletion region and if [ (qNd/e) (dφb/dE)−E] [ (d2φb/dE2) (dE/dV) ]≪1, where V is the applied voltage and e is the semiconductor permittivity, the slope of the (capacitance)−2 vs voltage relationship is constant and can be interpreted to give Nd. The voltage intercept of the relationship yields an apparent barrier height φa related to the true barrier φb by φa=φb−E (dφb/dE) + (qNd/2e) (dφb/dE)2, where q is the electron charge. From the measured variation of φa with Nd and one absolute measure of φb at one value of Nd, φb(E), and dφb(E)/dE may be deduced. From dφb(E)/dE the surface state density as a function of energy in the bandgap and the minimum value of interface thickness divided by relative interface permittivity can be obtained. Using the data of Archer and Atalla for vacuum cleaved Au‐Si diodes to illustrate our method, the surface state density is found to peak at a value of ∼2×1014 cm−2·eV−1 at about 0.83 below the conduction band and the minimum value of interface thickness divided by relative dielectric constant is found to be of the order of 5 A. Criteria are given which show how Schottky diode capacitance‐voltage data may be further used, in conjunction with photoelectric barrier measurements, to detect the presence of deep lying impurities or the penetration of surface state charge into the body of the semiconductor.

Tunneling in CdTe Schottky Barriers

Abstract: The tunneling characteristics of metal contacts on n−CdTe have been measured. Both the forward- and reverse-bias characteristics are in good agreement with the two-band model for the energy-complex-momentum relationship. The presence of trapping states increased the magnitude of the tunneling current at low levels by providing a two-step transition. The slope of the forward-bias log_e J−versus−V curves for tunneling through the intermediate states was reduced by a factor of 2.

p-n junction—Schottky barrier hybrid diode

Abstract: A new fabrication technique for passivated silicon Schottky barrier diodes is described. It is shown that the p-n junction guard ring or "hybrid" approach produces Schottky barriers whose forward and reverse electrical characteristics are in excellent agreement with simple theory, and that the excess noise normally found in passivated Schottky barrier diodes has been significantly reduced. The influence of metal barrier height and diffusion profile on the charge storage characteristics of these devices is discussed and examined experimentally.

Transport Properties of Metal-Silicon Schottky Barriers

Abstract: Schottky barrier diodes were fabricated by vacuum depositions of Au, Ag, and Cu onto chemically cleaned silicon surfaces and their current-voltage and capacitance-voltage characteristics were investigated in details over a temperature range between 100°K and 350°K. The current-voltage characteristics obtained are of nearly ideal Schottky barrier type and the current transport in the barriers is dominated by the thermionic emission and the image force effect. The temperature coefficient of the barrier height, the forward "n", and the image force dielectric constant were found to be (2.67±0.60)×10-4 eV/°K, 1.01~1.02, and 11.5e0 respectively. The departure from the ideal characteristics was explained by the generation-recombination current in the barrier region.

GaAs SCHOTTKY BARRIER AVALANCHE PHOTODIODES

Abstract: Uniform avalanche Schottky barrier photodiodes have been fabricated by plating a thin layer of platinum on GaAs and forming a guard ring by proton radiation. Operating at a gain of 100 these photodiodes exhibit gain‐bandwidth products greater than 50 GHz and enhanced signal to noise ratio in excess of 30 dB. The observed variation on the spectral response with bias can be accounted for by a change in the absorption of the Schottky barrier diode.

Properties of GaP Schottky barrier diodes at elevated temperatures.

Abstract: Gallium phosphide Schottky barrier diodes, discussing construction and metals used, barrier height relationships to impurity concentration and temperature, rectifying characteristics and internal quantum efficiency

Schottky Barriers on GaAs

Abstract: The forward current of Schottky barriers on n-type GaAs is investigated as a function of electron concentration in the range of 8×10^17 to 8×10^18 cm^−3 at temperatures 297-4.2°K. Both vacuum-cleaved and chemically polished surfaces are used. The majority of the junctions studied are gold Schottky barriers, but tin and lead contacts are also examined. The predominant current mechanism is field emission at liquid-nitrogen temperature and below for the range of electron concentrations used. These data are in excellent quantitative agreement at 77°K with the field-emission analysis of Padovani and Stratton if one uses a two-band model for the imaginary wave number kn. At 297°K, thermionic field emission predominates, but for an electron density above 3×1018 cm−3 the field-emission mechanism with a two-band model still gives reasonable agreement.

An Ag–GaAs Schottky‐Barrier Ultraviolet Detector

Abstract: Ag–GaAs Schottky‐barrier photodiodes have been fabricated and evaluated as detectors of uv radiation. The quantum efficiency of these detectors is a maximum near 3225 A, and is much less in the visible and ir regions of the spectrum. The peak quantum efficiency and selectivity of the detector is determined by the thickness of the silver layer, which possesses a narrow transmission ``window'' for radiation near 3225 A wavelength. The transmittance of silver films evaporated on 7059 glass and quartz substrates was measured and compared with calculations based on previously published optical constants. At the transmittance peak, the extinction coefficient for these silver films was measured to be 0.38. From these transmittance measurements, the fraction of the radiation, incident on the silver, which enters the GaAs of the photodetectors was calculated as a function of wavelength and silver‐film thickness. This quantity was compared with the measured quantum efficiency of the diodes. At the peak, the compari...

Homogeneous solution grown epitaxial GaAs by tin doping

Abstract: Tin doped epitaxial GaAs single crystals were grown from a Ga solution. The C-V characteristics of Schottky barrier diodes were used to determine the electron concentration profiles of the GaAs crystals. These profiles were flat within ± 5 per cent to a depth of 165 μ. The electron concentration was controlled at specified values between 3 × 1014 and 5 × 1016 cm−3. The distribution coefficient of tin in GaAs is 1 × 10−4 between 800 and 850°C.

Effects of contacts on the emission from indium antimonide

Abstract: The low‐field microwave emission from InSb subjected to parallel electric and magnetic fields is strongly dependent on the type of electrical contact attached to the sample. It is suggested that the radiation is a localized phenomenon due to high‐field regions or due to a Schottky barrier.

Thermionic‐field resistance maxima in metal‐semiconductor (schottky) barriers

Abstract: A maximum in the differential resistance versus applied bias relationship of metal‐semiconductor contacts is predicted to occur when current flow is predominantly by thermionic‐field (thermally excited tunnel) emission. The predicted resistance peaks are generally asymmetrical with respect to voltage and may occur on either side of zero bias. The peak location has only an indirect correlation with the Fermi kinetic energy in the semiconductor. The theoretical approach is generally applicable to any metal‐semiconductor system when the dominant carrier flux is associated with the tail of a Fermi‐Dirac distribution. The theory is in reasonable agreement with recent experimental resistance measurements on Cr–Si Schottky barrier diodes at 77°K.

Radiation Effects on Silicon Schottky Barriers

Abstract: Because of a variety of important new applications, it is desirable to determine the effects of radiation on silicon Schottky barrier diodes. In the present study, both neutron and low-energy electron irradiation were employed and a variety of Schottky diode structures were investigated. These included the p-n junction guard ring structure and a gate-controlled structure which was used to separate surface from bulk effects. The two main effects of low-energy electron irradiation are: increase of surface recombination velocity and buildup of a positive space charge in the oxide. These results are consistent with previous studies of p-n junction diodes. For Schottky diodes without gate electrodes, the breakdown voltage is decreased and some excess current is present at low forward bias after irradiation. The effects of nuclear irradiation are (in addition to the surface effects mentioned above): decrease of bulk lifetime and carrier removal, again consistent with previous studies on p-n junction devices. Recombination-generation current increases manyfold due to the decrease in lifetime after irradiation. This component of current is important for Pt Schottky diodes which have a high barrier (0.85 eV). However, for Al diodes, since the barrier is relatively low (0.69 eV) and the thermionic emission current relatively high, recombination-generation current is not important until very high neutron dosage.

SB-IGFET, II: An ion implanted IGFET using Schottky barriers

Abstract: Insulated-gate field-effect transistors have been made, which combine the advantages inherent to Schottky barrier source and drain electrodes with ion implantation. This device has a self-aligned gate structure achieved by using the thick gate electrode as a mask during the ion implantation process.

Negative resistance avalanche diode structures

Abstract: Undesired electron trapping in a Read diode is prevented in one embodiment by using a p+pnin+ structural configuration. In another embodiment, a metal-nin+ configuration is used, with the metal-semiconductor interface forming Schottky barrier.

Schottky barrier photodiode with a degenerate semiconductor active region

Abstract: A Schottky barrier photodiode possessing a high quantum efficiency and adapted to operate at long wavelengths. The photodiode is fabricated by providing a nondegenerate semiconductor substrate of one extrinsic conductivity type with a thin layer of a degenerate semiconductor material of the same extrinsic conductivity type as said substrate to form a barrier junction therebetween. The improved quantum efficiency exhibited by the photodiode of this invention is attributed to the use of a degenerate material as the active region.

Tunneling in Schottky Barrier Rectifiers

Abstract: When a metal is brought into intimate contact with a semiconductor there sometimes arises a potential barrier within the semiconductor which impedes the flow of electrons between it and the metal. The formation of such Schottky barriers will be described by Professor Mead and this chapter will be mainly concerned with the tunneling of electrons through them. Clearly, if a bias is applied between a metal and a semiconductor, current will flow. If the barriers are sufficiently thin and the temperature is sufficiently low, then the current flow will be primarily by electron tunneling. Conversely, for thicker barriers and higher temperatures the current flow will be due to thermionic emission over the barrier. We will also consider intermediate ranges of thickness and temperature, where the current is primarily due to tunneling of thermally excited carriers. This is the socalled TF emission first introduced by Dolan and Dyke (1) in connection with field emission from a metal tip.

Precision logarithmic converter

Abstract: Precision logarithmic conversion is achieved by utilizing a serial connection of Schottky barrier diodes in conjunction with an operational amplifier. Deviation from the desired logarithmic characteristic because of diode limitations, namely, reverse-bias saturation current, forward-bias resistance, temperature dependence and the like, is minimized by selectively supplying compensating signals into the input and output circuitry of the amplifier.

Schottky barrier semiconductor device having a substantially non-conductive barrier for preventing undesirable reverse-leakage currents and method for making the same

Abstract: A semi-conductor device, such as diode transistor, field effect transistor with a Schottky barrier, has a separation space formed underneath the insulating film covering a major surface portion of the semiconductor substrate. This separation space is disposed adjacent to a metal layer accommodated in a recess in the substrate and extending through an opening in the insulating film, so as to eliminate unreasonable reverse leakage current, by effectively insulating the Schottky barrier from the electric charge accumulation layer beneath the insulating film.

Schottky barrier semiconductor device

Abstract: A semiconductor device having a Schottky barrier is prepared by forming a hollow or recess in a major surface of a semiconductor substrate, such as silicon, germanium or gallium arsenide, and then forming a layer of metal, such as nickel, tungsten, molybdenum, vanadium, gold or palladium, in the recess. The metal contacting the semiconductor material forms a Schottky barrier in the recess. It is preferred that the recess exceed 200A. in thickness and that the thickness of the metal layer exceed the depth of the recess. In another embodiment, a layer of insulation is provided on the major surface of the semiconductor surface. Then, a hole is opened through the insulating layer and a recess is formed in the substrate. Thereafter, a metal layer is formed in the recess as described above.

Possible sources of error in the deduction of semiconductor impurity concentrations from Schottky-barrier (C, V) characteristics

Abstract: Experimental results are presented which show that surface contamination due to the method of preparation and bulk trapping centres can have a first-order effect on semiconductor impurity concentration measurements using Schottky barriers. A criterion is established which allows the reliability of the measurements to be assessed, and a method is given for measuring the impurity concentration in the presence of traps.

Avalanche photodiode utilizing schottky-barrier configurations

Abstract: An avalanche Schottky-barrier photodiode includes a symmetrical metallic grid network deposited over a semiconductor substrate and surrounded by one or more metallic guard rings. When a sufficiently high voltage bias is supplied to the metallic grid network, carriers generated by light impinging upon the semiconductor substrate through the grid network are multiplied by the avalanche gain operation of the photodiode.

Silicon and gallium arsenide field-effect transistors with Schottky-barrier gate

Abstract: Field-effect transistors with Schottky-barrier gates have been produced using epitaxial layers of n-type silicon on p-type substrates, and n-type gallium arsenide on semi-insulating substrates. Some simple design considerations are presented and the fabrication processes are discussed in detail. Comparisons are made between two different device geometries and between silicon and gallium arsenide devices.