Showing papers on "Schottky diode published in 1972"

Comments on the conduction mechanism in Schottky diodes

Abstract: The diffusion and thermionic emission theories of conduction in Schottky diodes are compared in terms of the behaviour of the quasi-Fermi levels for electrons. It is shown by an analysis of published experimental data that, for medium- and high-mobility semiconductors, the quasi-Fermi level is essentially flat throughout the depletion region under forward bias, in accordance with the thermionic emission theory. Under reverse bias the electron quasi-Fermi level is flat through most of the depletion region but rises as it approaches the metal, in agreement with the theoretical calculations of Crowell and Beguwala. The hole quasi-Fermi level remains horizontal through the depletion region at a value coincident with the Fermi level in the metal.

Admittance spectroscopy of deep impurity levels: ZnTe Schottky barriers

Abstract: A new method of deep‐level spectroscopy is demonstrated on ZnTe Schottky‐barrier diodes. Peaks in conductance measured as a function of temperature and frequency yield level depths and capture coefficients. A small‐signal theory is developed for numerical comparison to capacitance data, yielding level types and densities.

Many-body effects at metal-semiconductor junctions. I. Surface plasmons and the electron-electron screened interaction

Abstract: The electron-electron screened interaction near the metal-semiconductor junction is calculated analytically by the introduction of model bulk dielectric functions which contain all of the essential energy and wavelength dependent features of the real dielectric functions of the metal and semiconductor. The poles of the interaction give the dispersion relations for the surface plasmon excitations at the junction and these are studied for various parameters of the two bulk media. It is shown that there are two possible plasmon modes characteristic of bimetal and metal-classical dielectric interfaces. Also, the role of surface plasmons in Schottky barriers is discussed.

Linearized Third-Derivative Spectroscopy with Depletion-Barrier Modulation

Abstract: Low-field (third-derivative) electroreflectance spectra taken on fully depleted space-charge regions are shown to be linear in the modulation potential and free from experimentally induced line-shape distortions due to modulation wave-form, dc bias, or barrier-potential effects. Using a metal-semiconductor (Schottky diode) configuration, accurate threshold energies of the ${{E}_{0}}^{\ensuremath{'}}$ triplet of Ge are obtained. The observed spin-orbit-splitting energy of the valence band confirms that the highest transition also occurs at $\ensuremath{\Gamma}$.

Electroluminescence in reverse-biassed zinc selenide Schottky diodes

Abstract: Schottky diodes consisting of a metal layer in contact with an n-type ZnSe crystal are electroluminescent when biassed in the reverse direction. Electrons tunnel from the metal into the semiconductor, are accelerated in the depletion layer field and then impact-ionize luminescent centres. Experiments confirming each of these mechanisms are described. A simple theory is propounded to give a quantitative understanding of the processes and of the performance of the diodes as light sources.

Deep level impurity effects on the frequency dependence of Schottky barrier capacitance

Abstract: The frequency dependence of the capacitance of Schottky barriers is predicted for a single partially ionized deep level in combination with ionized shallow impurities. Shockley-Read recombination statistics, a gradient-free fermi level for free electrons and deep levels, a uniform impurity concentration, and an abrupt spatial transition in frequency response were assumed. The results apply at frequencies from d.c. to near that at which only the impurities in the bulk semiconductor respond and for any bias and temperature. A method is shown to determine the shallow and deep impurity concentrations, deep impurity energy level, and capture cross-section of the deep impurity level from the capacitance-frequency relationship at any temperature.

Background energy level spectroscopy in GaP using thermal release of trapped space charge in Schottky barriers

Abstract: The energy distribution and concentration of electrically active background impurities in GaP have been investigated by observing the current when space charge trapped at these impurities is thermally released within the depletion region of a Schottky barrier formed on the semiconductor. Large‐area Schottky barriers are used for these measurements in order that small concentrations of impurities may be detected. The measurements have been carried out for both liquid‐encapsulated‐Czochralski (LEC)‐ and liquid‐phase‐epitaxial (LPE)‐grown material using n‐type wafers. In LEC GaP, at least seven electrically active background levels are detectable and these exist at concentrations between 1 × 1015−3 × 1016 cm−3, while in LPE GaP only three or four are detectable and these exist in much smaller concentrations of about 1014 cm−3.

Determination of the defect nature of MoO3 films using dielectric‐relaxation currents

Abstract: A new technique, based on stimulated dielectric‐relaxation currents (DRC), has been successfully used to analyse the defect properties of Al–MoO3–Al systems. The particular aspect of the DRC technique used here consists of cooling the system to low temperatures with a voltage applied to the electrodes and then raising the sample temperature at a uniform rate with the electrodes short‐circuited. Pronounced structure is observed in the current‐temperature characteristics, which may be related directly to the donor (or trap) density and the donor (or trap) distribution. The measurements obtained from the Al–MoO3–Al samples have confirmed the existence of Schottky barriers at the interfaces and revealed the existence of a donor band in the MoO3, which is centered about an energy 0.27 eV below the bottom of the conduction band. The half‐width of the donor band is about 0.07 eV, and its density is approximately 1.5×1018 cm−3. These results are in excellent agreement with those obtained from previous ac and dc measurements. It has also been confirmed that an electrode‐limited to bulk‐limited transition occurs at about 0.6 V. The DRC technique is compared to the thermally stimulated current (TSC) technique, and it is concluded that the DRC method is the superior of the two, at least as far as thin films are concerned. Finally, the effect of Schottky barriers on conduction processes in thin films in general is discussed and it is shown that if they are present but overlooked, the interpretation of the data is invalid.

Schottky barrier diodes

Abstract: The series resistance of a Schottky barrier diode is reduced by grading the net activator concentration in the epitaxial layer of the diode from a minimum value at the face thereof at the barrier to a maximum value at the other face thereof in accordance with various profiles. In comparison to an epitaxial layer which is uniform in concentration and which is able to withstand a predetermined reverse voltage, the profile is set so that the diode concurrently is able to withstand the same predetermined voltage. Suitable profiles are one step, multistep and continuously graded.

Effects of microstructure on the radiation stability of amorphous semiconductors

Abstract: The influence of phase separated and crystalline regions on the fast neutron and X-ray damage thresholds of germanium chalcogenides and vanadia-phosphate semiconducting glasses has been established. Damage thresholds are shown to be a function of volume fraction and size of heterogeneities, and the bond energies of the glass. A theoretical model interpreting structure-dependent radiation damage is presented based on heterogeneous semiconductor theory and the destruction of interfacial Schottky barriers. Applications of the results to predicting the radiation sensitivity of amorphous semiconductor devices are suggested.

Semiconductor diode thermometry

Abstract: A temperature measuring apparatus is disclosed, in which the temperature sensing element is a semiconductor diode. The diode used is constructed such that carrier recombination takes place principally within the depletion region of the p-n junction. The temperature reading is made by measurement of the forward voltage drop across the diode as the diode current is switched between two current levels of a fixed ratio. The difference between the voltages measured at the two current levels is linearly proportional to the absolute temperature. The temperature scale thus defined is essentially constant from diode to diode from cryogenic temperatures to somewhat above room temperature.

Minority carrier diffusion length in liquid epitaxial GaP

Abstract: Using a Schottky diode photocurrent technique, investigations have been made of the room temperature value of minority carrier diffusion length in liquid epitaxial GaP grown on both (111) and (100) oriented pulled GaP substrates. Results are presented for undoped layers and layers doped separately with S, S and N, Te, Zn, and Zn and O, to cover a range of impurity concentration in the GaP. The measured values of minority carrier diffusion length are found to depend on the concentration of the dominant impurity and, for the undoped and Zn doped layers, also on the growth orientation of the substrate. From the dependence of the minority carrier diffusion length on majority carrier concentration we infer the dominant room temperature recombination process in the layers. In our undoped layers this process is believed to correspond to recombination via residual Si substituted on P sites. In Te, S, Zn, and Zn, O doped layers the dominant recombination mechanism can be attributed to a non-radiative band-band Auger process, although in the case of the Zn, O doped layers a competing recombination process is observed which is believed to correspond to recombination via centres formed by unpaired O and Zn defects. The lifetime for this competing process is predicted to be sensitive to annealing.

Schottky barrier diodes for solar energy conversion

Abstract: Several Schottky barrier solar cells were fabricated by evaporation and sputtering of Al ohmic contacts and Cr or AuCr alloy barrier metals on 0.5-10.0 2 Ω ċ cm p-type silicon. Potential efficiencies of 4.8 to 12 percent were observed which would be realized with improved fill factors. Computer studies of the optical problem indicate an output power increase by a factor of four through the use of reduced barrier metal thickness (from 275 to 100 A) and alloy barrier metals to more effectively transmit solar energy to the Schottky junction.

Injection luminescence and laser action in epitaxial PbTe diodes

Abstract: Thin‐film diode lasers have been made from Schottky barriers on epitaxial PbTe. At 77 °K the spontaneous emission spectrum agrees with that calculated for direct band‐to‐band transitions. At 12 °K laser action is observed in the pulsed mode with an average current density, at threshold, of (2–3) × 102 A cm−2. This is the first observation of diode laser action from evaporated thin films of any semiconductor.

Bistable Switching in Metal‐Semiconductor Junctions

Abstract: Bistable switching with memory has been achieved in various n‐type GaAs Schottky contacts and n‐type Si Schottky contacts doped with trap impurities. Transition from the low‐conductivity state into a high‐conductivity state is established after a delay of 10 nsec, when a threshold voltage is exceeded. With opposite bias direction, resetting occurs in 10 nsec by exceeding a current threshold. Either state is maintained over weeks without bias.

Current-field characteristics of AlAl2O3Al sandwiches in the regions of thermionic and T-F emission

Abstract: On the basis of the earlier proposed theory of electron emission in insulators more detailed expressions for the current density in the thermionic and thermionic-field region are developed under the assumption of a Schottky image potential barrier near the metal-insulator interface. Current-field characteristics of AlAl2O3Al sandwiches with relatively thick oxide layers (50–150 A) have been measured at suitable applied voltages. Rather good quantitative agreement between theoretical equations and experimental data is found.

Double-clamped schottky transistor logic gate circuit

Abstract: A double-clamped Schottky transistor logic gate circuit which includes a totem pole output with Schottky clamp transistors with the pull-down transistor supplying a stable low output level and the pull-up transistor provides a high stable output level voltage by use of a negative feedback arrangement which includes level shifting Schottky diodes and a second Schottky clamp transistor to control the current to the pull-up transistor. An output gating arrangement utilizing Schottky diodes provides reduced capacitances and chip area by placing the cathode of the diode in the same isolated integrated semiconductor regions as the collector of the pull-down transistor. In addition, temperature compensation is provided and noise immunity is improved by integrating a voltage regulator into the same integrated circuit.

Platinum silicide‐aluminum Schottky diode characteristics

Abstract: The effects of heat treatment on platinum silicide Schottky diodes with aluminum metal contacts have been investigated. It has been found that the aluminum reacts with the silicide causing a change in the effective metal‐semiconductor barrier height over a range of approximately 0.25 eV. Schottky diodes with initial platinum silicide characteristics convert to devices with barrier heights characteristic of aluminum after extended heat treatments.

Schottky barriers on ZnTe

Abstract: Metal surface barriers consisting of gold, nickel, tantalum, and aluminum on zinc telluride have been investigated. The behavior of gold and nickel barriers agrees with simple thermionic Schottky barrier theory. The barrier height found for gold is 0.64 eV and for nickel 0.65 eV. Tantalum and aluminum barriers were found to have characteristics dominated by recombination currents. The barrier height found for tantalum is 1.50 eV and for aluminum 2.00 eV.

Beam-lead semiconductor component

Abstract: A beam-lead semiconductor component is, for example, a beam-lead Schottky diode, which includes a Schottky metal-semiconductor contact structure with one additional non-blocking contact structure. The semiconductor structure is formed with regions of different doping levels but of the same conductivity type having an insulating layer thereover which contains openings at at least two points, the two openings being over the regions of the different doping levels respectively and the region of lesser doping being formed in the upper surface of said other region. The regions exposed below said opening are provided with metal layers respectively. Contacts extend down into the openings into electrical contact with said metal layers respectively. These contacts come from correction with beam lead terminals which are provided on the surface of the insulating layer. The beam lead connections extend out from the component so that the semiconductor arrangement can be soldered in a self-supporting fashion directly into circuits. This avoids the occurrence of housing capacitances which do occur, for example, in the case of encapsulated diodes. The contact extending into the opening to the region of higher doping level is spaced from the region of lower doping level, with insulating material being therebetween. An ohmic contact is formed on the underside of the region having the higher doping level.

High-efficiency operation of GaAs Schottky-barrier IMPATTs

Abstract: CW GaAs Schottky-barrier IMPATT oscillators have been fabricated using nichrome as the barrier metal. Several of the oscillators exhibited CW efficiencies ranging from 15 percent to 17.5 percent in C and X band. The best result was 19-percent efficiency in X band from an oscillator which produced 700 mW of output power. Noise performance which is comparable to those of transferred electron oscillators and reflex klystrons has also been observed.

Schottky clamped ttl circuit

Abstract: A low power TTL gating circuit wherein PNP transistors have been used in place of the usual current source resistors and Schottky-clamped NPN have been used in place of the usual gold doped NPN gating elements to obtain a faster operating circuit which requires less chip area than similar prior art circuits.

The rectifying contact of gold on etched CdTe single crystals

Abstract: An investigation was made of the fundamental electrical properties of diodes prepared by the precipitation of gold on mechanically polished and chemically etched surfaces of n-type CdTe monocrystals. The forward I–U characteristics measured in the temperature range from 210 to 300 K can be explained by Schottky's theory of metal–semiconductor junction with recombination in the space charge region. The reverse I–U characteristics are in good agreement with Schottky's theory at room temperature only. At lower temperatures a strong increase of the current with increasing voltage was observed. This effect may be explained by the current tunnelling through the high resistivity layer formed between the metal and the semiconductor. [Russian Text Ignored].

Moat-etched Schottky barrier diode displaying near ideal I–V characteristics

Abstract: A simple fabrication technique for Schottky diodes allows achievement of high breakdown voltage without sacrifice of speed at any current level. We have found the reverse blocking voltage of a Schottky diode can be increased to 80–90% of the bulk breakdown voltage of the silicon wafer by moat-etching into the wafer before deposition of the barrier metal. The moat-etched device exhibits the low leakage current and high reverse breakdown voltage characteristic of a guarded Schottky diode, but retains the fast switching speed of a planar device. In addition, it is observed that the moat-etched diode exhibits a lower barrier height than conventional planar or guarded structures so that a smaller junction area is required for given forward current in the moat-etched device. Junction areas as large as 0.11 cm 2 have been investigated.

Self-heating and gate leakage current in a guarded MOSFET

Abstract: Gate leakage current measurements of a guarded MOSFET show that device self-heating has a marked effect on the Schottky emission current. This effect can make the bias conditions for zero gate leakage current very sensitive to changes in drain voltage.

Electron beam fabrication of submicrometer diameter mixer diodes for millimeter and submillimeter wavelengths

Abstract: Using an electron beam fabrication technique, GaAs Schottky barrier diodes have been produced with submicrometer dimensions, which is a considerable reduction in size over that attainable using conventional photoresist techniques. This advancement should improve the performance of Schottky barrier mixers and detectors at millimeter wavelengths and extend their use to submillimeter wavelengths.

Transient Ionizing Radiation Effects on Baritt Diode Oscillators

Abstract: The performance of a variety of IMPATT diode oscillators has been measured under transient ionizing radiation conditions, and the results of a large signal model which agrees with experiment are presented. Five hundred milliwatt cw diode oscillators (silicon and gallium arsenide with various types of avalanching junctions) were exposed to 100 nanosecond pulses of 10 MeV electrons at dose rates between 2 × 108 and 8 × 109 rads/sec. With these oscillators, the RF power is reduced at increasing dose rates and is quenched entirely during the radiation pulse at a dose rate dependent upon the DC bias current (greater than 5 × 109 rads/sec for 500 mW oscillators in vacuum). With diodes open to air, oscillators in low Q cavities were quenched during the radiation pulse with a total dose of 500 rads. The results of a large signal theory including the effects of leakage current are presented that agree well with the RF power decrease during irradiation.

Method of manufacturing a semiconductor capacitance diode

Abstract: A METHOD OF MANUFACTURING A SEMICONDUCTOR CAPACITANCE DIODE IN WHICH A LARGE CAPACITY VARIATION AND AN EXPONENTIAL VARIATION OF THE CAPACITY-VOLTAGE CHARACTERISTIC ARE OBTAINED BY THE FOLLOWING MANUFACTURING STEPS: (1) NO, ONE OR SEVERAL EVER LOWER OHMIC LAYERS OF THE SAME CONDUCTIVITY TYPE ARE PROVIDED ON THE HIGH-OHMIC LAYER ON A LOW-OHMIC SUBSTRATE. (2) BY A SUITABLY THERMAL TREATMENT, THE STEP-LIKE DOPING PROFILE RESULTING FROM THE PROVIDED LAYER IS ROUNDED OFF BY OUT-DIFFUSION. (3) PRIOR TO PROVIDING THE P-N JUNCTION IN THE LAST LAYER, AT LEAST ONE OUT-DIFFUSION OF DOPING MATERIAL CAUSING THE SAME CONDUCTIVITY TYPE IS CARRIERD OUT, AS A RESULT OF WHICH THE CONDUCTIVITY IS FURTHER INCREASED.

Direct Measurement of Impurity Distribution in Semiconducting Materials

Abstract: Differential capacitance‐voltage measurements are commonly used to determine the impurity distribution in a semiconducting material whereby a Schottky or a diffused junction is reverse biased by a dc voltage. If the biased junction is driven by an ac current, the voltage generated by the diode contains first and second harmonics of the frequency of the driving current. The first harmonic is proportional to the depletion width and the second harmonic to the inverse of the impurity density, thus providing an absolute representation of the impurity distribution without any computations. The ratio of the amplitude of the second harmonic to the amplitude of the first harmonic, is, however, very small and separation of the second harmonic from the first harmonic requires a carefully designed circuit. The method and the electrical circuit is described in detail. Limitations of the technique and the methods for eliminating these limitations are also discussed.

Performance and stability of schottky barrier mixers

Abstract: We discuss the performance of a Schottky barrier diode as a mixer when the barrier of the diode is open-circuited at the harmonics 2ω o , 3ω o , etc. of the pump frequency ω o . Such a mixer is shown to be capable of arbitrarily high conversion gain provided $\omega_{c} \geqq \eta\omega_{o},$ where ω c , is the cutoff frequency of the diode and η is a parameter that is typically less than 6.25 and approaches 4 under certain ideal conditions. It is shown that the limit imposed by the series resistance of the diode on the double-sideband noise figure of the mixer is given by $F_{m} > \left(1 - \eta {\omega_{o} \over \omega_{c}\right)^{-1}.$ An experiment is described at 1.25 GHz on a room temperature mixer whose double-sideband noise figure F m as a function of gain has a minimum of about 0.7 dB (for gain less than unity) and a maximum of about 2.3 dB (for high gain).