Showing papers on "Schottky diode published in 1983"

A note on the correlation between the Schottky-diode barrier height and the ideality factor as determined from I-V measurements

Abstract: An expression is derived which relates the barrier height and ideality factor of a Schottky diode as determined from I-V measurements. The expression agrees well with data from PtSi diodes formed with a range of Pt thicknesses.

A reevaluation of the meaning of capacitance plots for Schottky‐barrier‐type diodes

Abstract: Capacitance–voltage (C‐V) data, in the form of 1/C2 versus voltage plots, have long been used to extract information on the space charge region doping and barrier height in Schottky‐barrier‐type diodes. The meaning of the slope and voltage intercept of these 1/C2 versus voltage plots for reverse‐biased diodes is reexamined in this analysis for the case when there is an inadvertent or purposeful interface layer present. The possibility of having interface states, one type of which communicates with the metal and another type of which communicates with the semiconductor, is considered, as is the fact that these two classes of states may, or may not, be able to follow an ac signal. The analysis first assumes that the densities of these states do not vary across the gap; this restriction is later relaxed and the possibility of variable densities of interface states is considered. The results of the analysis differ from those of previous studies. In general, it is found that most sets of interface state charac...

Schottky barrier type diode with an electrochemically prepared copolymer having pyrrole and N‐methylpyrrole units

Abstract: A Schottky type diode has been constructed with the electrochemically prepared copolymer having pyrrole and N‐methylpyrrole units and a low work function metal (In). The heat treatment of the copolymer in air was performed in order to stabilize the electrical characteristics of the device before the deposition of a blocking electrode. The electrical properties have been investigated by means of I–V and C–V measurements. The diode quality factor and the barrier height have been obtained to be n=1.2 and ψb=0.81 V by applying a thermionic emission theory, respectively. At high current densities in the forward direction, a space‐charge‐limited current has been observed. This observation would be due to the charge‐injection across the thin oxidized layer which would be formed during the heat treatment of the copolymer in air. Other junction parameters have been also determined by means of C–V measurements.

100 GHz bandwidth planar GaAs Schottky photodiode

Abstract: In the letter we report the development and characterisation of a planar-structure GaAs Schottky-barrier photodiode whose response to a mode-locked laser pulse of 600 nm wavelength has a full-width half-maximum of 5.4 ps and a 3 dB bandwidth of 100 GHz.

Schottky diodes with high breakdown voltages

Abstract: The methods of increasing the breakdown voltages in silicon Schottky diodes is presented. In addition to a guarding ring, screen-diffusion regions were introduced. In this manner, the electrical field near the Schottky contact was lowered and, as a result, higher breakdown voltages were obtained. By using this method, the breakdown voltage can be increased by a factor of 3–5. However, a large device area is required for the same Schottky contact area and, therefore, the junction parasitic capacitance is greater.

Topics in the Optimization of Millimeter-Wave Mixers

Abstract: A user oriented computer program for the analysis of single-ended Schottky diode mixers is described. The program is used to compute the performance of a 140 to 220 GHz mixer and excellent agreement with measurements at 150 and 180 GHz is obtained. A sensitivity analysis indicates the importance of various diode and mount characteristics on the mixer performance. A computer program for the analysis of varactor diode multipliers is described. The diode operates in either the reverse biased varactor mode or with substantial forward current flow where the conversion mechanism is predominantly resistive. A description and analysis of a new H-plane rectangular waveguide transformer is reported. The transformer is made quickly and easily in split-block waveguide using a standard slitting saw. It is particularly suited for use in the millimeter-wave band, replacing conventional electroformed stepped transformers. A theoretical analysis of the transformer is given and good agreement is obtained with measurements made at X-band.

Characterization of WSix/GaAs Schottky contacts

Abstract: The Schottky diode characteristics of WSix contacts on n‐type GaAs have been investigated and correlated to the film stress in WSix and crystallographic properties of the film. Experimental results show that (1) the high‐temperature stability of WSix/GaAs Schottky diode characteristics depends significantly on Si content; (2) WSix/GaAs contacts exhibit very high‐temperature‐stable Schottky diode characteristics at Si content around 0.60, and at this Si content no metallurgical interactions between WSix and GaAs are observed by 2‐MeV 4He+ Rutherford backscattering (RBS) measurements; (3) the optimum Si content for Schottky diode characteristics coincides with that for stress minimum in WSix; (4) the Schottky diode characteristics are not affected by whether WSix is crystallized or not, and a common feature of the regions where the Schottky diode characteristics are very high‐temperature stable is that each consists of single‐phase (W5Si3 secondary solid solution or amorphous).

TEMPERATURE DEPENDENCE OF THE I-V CHARACTERISTICS OF MODULATION-DOPED FETs.

Abstract: Both normally on and normally off modulation‐doped FETs have been fabricated from MBE grown AlGaAs/GaAs heterojunction structures. The static I–V characteristics of recessed‐gate FETs were measured over the temperature range 77–400 K. A large change in the threshold voltage Vt with temperature T was observed. The observed Vt(T) data are explained, in part, in terms of a simple model based on the temperature‐dependent occupation of deep donor traps in the AlGaAs layer. The traps were characterized by different energies for emission and capture. The transient capacitance of large area modulation‐doped Schottky diodes was also measured. The capacitance data is explained by the time‐dependent occupation of the same donor traps. The value of the activation energy for carrier emission was estimated to be 450 mV while the donor level was found to be about 42 mV below the conduction band.

Photovoltaic effect in gold‐indium selenide Schottky barriers

Abstract: Photovoltaic effect has been extensively investigated in gold‐indium selenide Schottky barriers, realized by vacuum evaporation of gold on freshly cleaved surfaces of indium selenide single crystals. Continuous and pulsed excitation has been used to determine the fundamental parameters governing the photovoltaic effect. A barrier height of 0.65 eV has been found from current‐voltage (I‐V) and capacitance‐voltage (C‐V) characteristics, and by means of the spectral dependence of the photoemission current. A diffusion length of about 10 μm and a lifetime of about 15 μsec of the minority carriers have been determined by measuring both the spectral response of the short‐circuit current and the transient photocurrent decay. Finally, a photovoltaic efficiency for solar energy conversion of about 2% has been evaluated.

Modification of Schottky barriers in silicon by reactive ion etching with NF3

Abstract: Reactive ion etching of silicon with NF3 gas has been found to alter the silicon surface such that the Schottky barrier height is systematically changed with ion energy. The energetic ions introduce a net positive surface charge which increases the barrier height on p‐Si and decreases it on n‐Si. The Schottky barrier modification is found to be a function of ion energy as well as gas plasma used.

Electrical properties and ion implantation of epitaxial GaN, grown by low pressure metalorganic chemical vapor deposition

Abstract: High quality single crystal GaN films with extremely uniform thicknesses have been grown in low pressure metalorganic chemical vapor deposition system using the reaction of (C2H5)3Ga with NH3. Electrical and optical properties of the layers were measured. Schottky barriers were fabricated after compensating the background donor concentration (typically ND ∼1×1019 cm−3) with Be+ or N+ implants. These Schottky barriers were electrically and optically characterized.

Polypyrrole‐semiconductor Schottky barriers

Abstract: Junctions between polypyrrole, a conducting polymer formed by electrooxidation, and n‐type semiconductors have been studied. Cadmium sulphide and titanium dioxide were chosen as substrates as a complement to earlier studies on silicon. The junctions behave as Schottky barriers on these semiconductors. The series resistance of the polypyrrole film is large and was taken into account in the evaluation of the data. The barrier heights of the junctions are compared with those found with ordinary metals. It is deduced that the work function of polypyrrole must be close to 5 eV.

Infra red detectors

Abstract: A detector in which a barrier region is interposed in the current path between the emitter and collector of the detector. This region is of a material having a valance band edge approximately level to that of the emitter material and an appreciably wider band gap. It thus serves to impede majority carrier current flow and as a consequence device resistance is high. When the detector is biased, the pedestal contribution to detector signal is low. The collector may be of semiconductor material of the same majority carried type as the emitter material; or may be of opposite type but dopant enriched; or it may be a Schottky metal contact. In one variant of the detector, the emitter and collector are located on opposite sides of the barrier and are of different bandgap materials. The infra red band response of this detector can be changed by reversing bias polarity. In another variant of the detector the emitter is in strip form and has a pair of bias contacts. The barrier and collector are located on the strip at a position between these contacts and provide a high resistance read-out structure. In one further variant of the detector the emitter, the collector, together with additional emitter-collector regions, are formed from a single layer of photosensitive material on one side of the barrier and provide a high resistance, series connected, multi-element structure.

20‐GHz bandwidth GaAs photodiode

Abstract: A high‐speed GaAs Schottky barrier photodiode with 3‐dB bandwidth of 20 GHz, an external quantum efficiency at 600 and 845 nm of ≥25%, and operating at less than 5‐V reverse bias is reported. Accurate characterization of these devices in both the time and the frequency domains is discussed.

Two-pole overcurrent protection device

Abstract: A two-pole overcurrent protection device comprises an integrated circuit with a thyristor having an emitter layer and base layer which, on the cathode side, is connected to the emitter layer on the cathode side by means of a normally non-conducting MOS transistor. The on-state voltage across the thyristor is supplied to the control electrode of the transistor via a Schottky diode, whereby, at a certain thyristor current, the thyristor is made conducting and short-circuits the cathode-emitter junction. The edge of the Schottky diode is arranged adjacent to the cathode base layer and at such a distance therefrom that the barrier layer at the center junction of the thyristor penetrates into the diode and limits the voltage on the control means of the MOS transistor to a harmless value.

Mos and schottky diode gas sensors using transition metal electrodes

Abstract: MOS and Schottky diode devices with various gate metals and semiconductor substrates were used as sensitive detectors of hydrogen and hydrocarbon based gases. MOS devices were fabricated on n-and p-type silicon substrates with the following gate metals and dielectric materials: Pd-SiO2, Pd-Ti-SiO2, Pt-SiO2, Ni-SiO2, Pd-Si3N4, Pd-Si3N4-SiO2 and Pt-Si3N4. In MOS devices with InP substrates, a Pd-Si3N4. device was tested. Also, Pdn type InP and Pd-GaAs were used as gaseous detectors in the Schottky barrier configuration. Detection capability of these devices was tested with H2, CH4, C2H4 and C4H10 gases. The characteristic parameters of these devices, such as sensitivity limits, adsorption and desorption time constants and linearity of time constants and linearity of response are given and a tentative detection mechanism is presented.

Study of metal-semiconductor interface states using Schottky capacitance spectroscopy

Abstract: In a forward-biased Schottky diode, the charge of the interface states can be electrically modulated. This results in the appearance of additional capacitance whose variations with frequency, bias and temperature can be used to determine the characteristic parameters of the states (energy position, density, capture cross sections). A simple model is described, taking into account any possible charge exchanges between the interface states and the three 'reservoirs' surrounding them (conduction and valence bands of the semiconductor and conduction band of the metal). Limit cases where one or two of these exchange paths are dominant are detailed and a few typical experimental examples are given.

A study of interface states in metal‐GaAs 〈110〉 structures by Schottky capacitance spectroscopy

Abstract: A study of the capacitance of a forward biased Schottky diode as a function of bias, temperature, and frequency allows characterization of interface states at the metal‐semiconductor junction. This method, called Schottky Capacitance Spectroscopy is applied to interfaces obtained by evaporating Au, Ag, or Al onto n‐type cleaved GaAs 〈110〉 surfaces. We have explored the region of the semiconductor band gap about 1 eV below the conduction band minimum. There is evidence of three kinds of states. The energy levels of these states are quite reproducible while we have obtained a light dispersion of density of states and capture cross sections. Moreover, we have observed a correlation between the relative density of states C and the degradation of the I–V characteristic.

n-Type silicon photoelectrochemistry in methanol: Design of a 10.1% efficient semiconductor/liquid junction solar cell

Abstract: n-Type Si electrodes in MeOH solvent with 0.2 M (1-hydroxyethyl)ferrocene, 0.5 mM (1-hydroxyethyl)ferricenium, and 1.0 M LiClO4 exhibit air mass 2 conversion efficiencies of 10.1% for optical energy into electricity. We observe open-circuit voltages of 0.53 V and short-circuit quantum efficiencies for electron flow of nearly unity. The fill factor of the cell does not decline significantly with increases in light intensity, indicating substantial reduction in efficiency losses in MeOH solvent compared to previous nonaqueous n-Si systems. Matte etch texturing of the Si surface decreases surface reflectivity and increases photocurrent by 50% compared to shiny, polished Si samples. The high values of the open-circuit voltage observed are consistent with the presence of a thin oxide layer, as in a Schottky metal-insulator-semiconductor device, which yields decreased surface recombination and increased values of open-circuit voltage and short-circuit current. The n-Si system was shown to provide sustained photocurrent at air mass 2 levels (20 mA/cm2) for charge through the interface of >2,000 C/cm2. The n-Si/MeOH system represents a liquid junction cell that has exceeded the 10% barrier for conversion of optical energy into electricity.

A study of Schottky contacts on indium phosphide

Abstract: The Schottky‐barrier energy φB for Al, Ni, Pd, Co, Au, and Ag contacts on chemically etched 〈100〉 surfaces of both p‐ and n‐type InP was measured and the metallurgical behavior of the contact structures was studied using Auger‐electron spectroscopy. No simple linear relationship could be found between the measured Schottky barrier energies on InP and the work functions or the electronegativities of the contact metals. Therefore, the results could not be explained in terms of the traditional Schottky and Bardeen theories. However, a very well defined relationship was observed between the Schottky barrier energies and the heats of reaction per formula unit ΔHr for the most stable metal phosphides that could be formed between the contact metals and the InP substrate. The contact metals Au and Ag whose phosphides are less stable than InP (i.e., ΔHr >0) produced diffuse interfaces, characterized by extensive outdiffusion of In, and yielded low values of φBp, the Schottky‐barrier energy on p‐type InP; whereas t...

Heterojunction Schottky gate MESFET with lower channel ridge barrier

Abstract: An FET with an extremely short channel formed by the apex of a substrate ridge structure protruding upward through the channel layer toward a Schottky-barrier gate contact. The device is formed by etching a modulation-doped substrate to form an upwardly protruding ridge with the apex modulation-doped. A semiconductor layer is then disposed over the substrate surface with the protruding ridge to obtain an epitaxial interface therebetween. Source and drain regions are doped into the semiconductor layer on opposite sides of the ridge structure. Finally, ohmic contacts are formed on the semiconductor layer over the source and drain regions and a Schottky-barrier metalization is deposited on the semiconductor layer above the ridge structure. This device has a very short channel, a low transit time, a low gate capacitance, and an enhanced transconductance.

Deep mesa process for fabricating monolithic integrated Schottky barrier diode for millimeter wave mixers

Abstract: A method of fabricating gallium arsenide devices in which contact isolation is provided by a deep mesa step structure. Step coverage of deposited conductive films is facilitated by preferential orientation of the non-centrosymmetric crystal substrate and wet anisotropic etching that provides a sloped step. Problems of fine line definition of the Schottky anode contact in the photolithographic process are addressed by a two-step exposure of a single layer of thick photoresist followed by a chlorobenzene soak prior to development that ensures a retrograde resist profile needed for good lift-off of undesired evaporated metal. Mesas as deep as 7 μm have been obtained, which permit the fabrication of monolithic planar mixer millimeter-wave diodes with low series resistance and reduced parasitic capacitance.

Analysis of parallel Schottky contacts by differential internal photoemission spectroscopy

Abstract: A differential analysis of internal photoemission spectroscopy has been developed for the study of nonuniformity in a Schottky contact The analysis is capable of revealing the presence of a high‐low parallel contact in a spectroscopic manner It has been applied to a discrete parallel contact consisting of Pd2Si and NiSi as well as a nonuniform contact of Pd on Si in the as‐deposited state The nonuniformity in the latter case is due to the existence of high barrier regions (086 eV) in parallel to those of Pd2Si (074 eV) and it disappears after a subsequent annealing at 250 or 450 °C

Ion-cleaning damage in (100) GaAs, and its effect on schottky diodes

Abstract: This study investigates the effect of ion cleaning damage of (100) GaAs in the 100–1000 eV range, and also its recovery with thermal annealing to 400°C. It is shown that GaAs could be annealed to a considerable extent if the ion-damage was ⩽ 100 eV. However, full recovery was not achieved. On the other hand, samples damaged at ⩾ 400 eV became progressively worse with annealing. Measurements indicate that these samples are dominated by the effect of arsenic variances within the bulk. These remain in the bulk, but are distributed spatially upon annealing. They behave as deep donors, so that the net electron concentration in the bulk is enhanced. Aluminum-n GaAs Schottky diodes were used as a vehicle for this study.

On the mechanism of light‐induced effects in hydrogenated amorphous silicon alloys

Abstract: We have investigated the effects of both forward bias current soaking in the dark and prolonged light exposure on the photovoltaic properties of lightly doped, n‐ and p‐type hydrogenated amorphous silicon Schottky barrier diodes. The results show that recombination rather than single carrier trapping is responsible for the light‐induced changes.

Characteristics of Schottky diodes with microcluster interface

Abstract: We present experimental evidence that a single Schottky diode on GaAs is an agglomorate of paralleled microjunctions with different barrier heights and saturation currents. The current‐voltage characteristic of the cluster breaks up into sections of exponentials with different slopes as one cools the diode from 300 to 10 K. Noise measurements performed on cooled diodes at 4 GHz also confirm that a single device is a cluster of paralleled diodes.

Barrier height and leakage reduction in n‐GaAs–platinum group metal Schottky barriers upon exposure to hydrogen

Abstract: Current–voltage (I–V), capacitance–voltage (C–V), and photovoltage (PV) data are obtained for Ru, Rh, Pd, Os, Ir, and Pt contacts deposited on chemically cleaned 〈100〉 n‐GaAs wafers. By explicitly evaluating the relevant equations using realistic values of all parameters, we show that the currents obtained for small voltages are far too large to be explained by thermionic or recombination effects alone but are indicative of barrier height variations as proposed by Freeouf et al. We used the fact that the thermionic emission component is always present to reconcile the difference between apparent barrier heights determined by I–V and C–V measurements to obtain a consistent set of values for all materials. Upon exposure of the Ru and Ir contacts to atmospheric‐pressure hydrogen, the barrier heights are reduced by 160 and 70 mV, respectively, and the ideality factors by 0.3 and 0.3, showing that hydrogen simultaneously lowers the barrier height and makes it more uniform over the contact for these junctions. ...

High temperature stability of PtSi formed by reaction of metal with silicon or by cosputtering

Abstract: High temperature stability of platinum silicide, formed by reacting metal with silicon or by cosputtering metal and silicon in a desired ratio, has been studied. The properties of films, thus formed, were examined as a function of annealing temperature using a resistance measuring technique, Rutherford backscattering, Auger and x‐ray analyses, transmission and scanning electron microscopic techniques, and by measuring forward current‐voltge (I‐V) characteristics of the silicide n‐silicon Schottky diodes. It is shown that cosputtering silicon rich alloys prevents agglomeration of the silicide, but increases the resistivity and decreases the Schottky barrier height of the film. Platinum silicide dissolves increasing amounts of silicon on high temperature (700–1000 °C) treatments causing considerable degradation of properties. Although cosputtering silicon rich alloys reduces this behavior, electrical properties such as forward I‐V characteristics still degrade due to high temperature anneals.

1/f noise in polycrystalline silicon resistors

Abstract: The 1/f noise in polycrystalline silicon resistors has been measured at room temperature. The resistors were manufactured in low‐pressure chemical vapor deposition films, implanted with B, P, and As and processed in two different technologies with different temperature cycles. The spectral density was essentially independent of the type of implantation and of the processing. The results can be described with Hooge’s empirical law and Kleinpenning’s model for the 1/f noise in Schottky barriers. At low doping levels Hooge’s constant turned out to be ∼4×10−3 and it decreased with increasing doping concentration, more or less as (μ/μlattice)2.