Showing papers on "Schottky diode published in 1981"
TL;DR: In this article, the conduction and valence-band width of amorphous silicon hydride is inferred from time-of-flight measurements of the temperature dependence of the electron and hole drift mobilities, and a multiple-trapping model of dispersive transport.
Abstract: The width of the conduction- and valence-band tails in amorphous silicon hydride are inferred from time-of-flight measurements of the temperature dependence of the electron and hole drift mobilities, and a multiple-trapping model of dispersive transport.
447 citations
IBM1
TL;DR: In this paper, a new model of Fermi-level pinning at the interfaces of compound semiconductor substrates and metallic or oxide overlayers was proposed, which assumes the standard Schottky picture of interface band alignment, but the interface phases involved are not the pure metal or oxide normally assumed by other models.
Abstract: The experimental observations of metallurgical interactions between compound semiconductor substrates and metallic or oxide overlayers have stimulated a new model of Fermi level ’’pinning’’ at these interfaces. This model assumes the standard Schottky picture of interface band alignment, but that the interface phases involved are not the pure metal or oxide normally assumed by other models. For both III‐V and II‐VI compounds, the barrier height to gold is found to correlate well with the anion work function, suggesting the interface phases are often anion rich. This correlation holds even for cases in which the ’’common anion rule’’ fails, and explains both successes and failures of this earlier model.
349 citations
TL;DR: A thin organic film of polycrystalline particles of metal free phthalocyanine (x−H2Pc) dispersed in a polymer binder, when sandwiched between tin oxide (NESA) and indium electrodes, is shown to exhibit a strong photovoltaic effect as discussed by the authors.
Abstract: A thin organic film of polycrystalline particles of x‐metal free phthalocyanine (x‐H2Pc) dispersed in a polymer binder, when sandwiched between tin oxide (NESA) and indium electrodes, is shown to exhibit a strong photovoltaic effect. The photovoltaic and rectification properties of In/x‐H2Pc/NESA sandwich cells are reported. From the photovoltaic action spectra, the active region responsible for electric power generation was found to be confined to the metal/semiconductor interface. A Schottky barrier width of 300 A was determined, which allows the capture of 30% of solar irradiance. An electron trap density of 3×1017/cm3 and a Schottky barrier built‐in potential of 0.63 V are estimated from C‐V measurements. At low voltage, the dark current in the forward direction varies exponentially with voltage: from this dependence values of 2×10−9 A/cm2 and 1.3–2.6 for the saturation current J0 and diode quality factor n are determined. At higher voltage, a super quadratic dependence of forward current on voltage i...
180 citations
TL;DR: In this article, the authors reported energy conversion efficiency as high as 5.96% on polycrystalline transparent magnesium Zn3P2 diodes, 0.7 cm2 in area, tested under simulated AM1 illumination.
Abstract: Energy conversion efficiencies as high as 5.96% are reported on polycrystalline transparent magnesium Zn3P2 diodes, 0.7 cm2 in area, tested under simulated AM1 illumination. The transparent Mg films with low sheet resistivities are obtained by dc sputtering. The effective minority‐carrier diffusion length in Zn3P2 is estimated from spectral response measurements and correlates well with the measured short‐circuit current. Loss analysis of the present cells shows a practical upper limit of 9% in conversion efficiency.
159 citations
TL;DR: Pd/Si MIS Schottky diode hydrogen detectors have been fabricated with a response of 2-3 orders of magnitude change in current for 154 ppm of H 2 in N 2 as mentioned in this paper.
Abstract: Pd/Si MIS Schottky diode hydrogen detectors have been fabricated with a response of 2-3 orders of magnitude change in current for 154 ppm of H 2 in N 2 . Detailed evaluation of dark I-V, C-V, illuminated I-V, and internal photoemission data unambiguously ascribes the strong hydrogen sensitivity of these diodes to hydrogen-induced change in the work function of Pd, rather than to any surface-state effects. The reaction rate of the device to different gas ambients has been studied with time response measurements. A long-term degradation mechanism has been identified and traced to the poisoning of Pd by environmental sulfur. The role of oxygen and atomic hydrogen in determining the Schottky barrier height also is discussed in some detail.
152 citations
TL;DR: Ohmic and Schottky barrier contacts with desired properties are difficult to form on GaAs devices due to the fact that the position of the Fermi energy is loosely "pinned" near midgap for GaAs surfaces which are metallized using conventional techniques.
Abstract: Ohmic and Schottky barrier contacts with desired properties are difficult to form on GaAs devices. This is due mainly to the fact that the position of the Fermi energy is loosely ’’pinned’’ near midgap for GaAs surfaces which are metallized using conventional techniques. Doped alloyed metal ohmic and refractory metal Schottky contacts formed on carefully cleaned surfaces are currently widely used. New contacting techniques including the use of lattice matched heterojunctions, nonalloyed n++ and p++ surfaces, graded band gap structures, and special surface treatment prior to metallization promise to provide both greater flexibility and control for future applications.
132 citations
TL;DR: In this article, anomalous rectifying behavior has been observed in molybdenum/silicon Schottky barrier diodes produced by ion-beam sputter deposition of Mo on singlecrystal Si.
Abstract: Abnormal rectifying behavior has been observed in molybdenum/silicon Schottky barrier diodes produced by ion‐beam sputter deposition of Mo on single‐crystal Si. Rectifying, rather than ohmic contacts are obtained on p‐type Si, while ohmic behavior is seen on n‐type Si. These results are contrary to the usual results reported in the literature, and are shown to be caused by ion‐beam surface damage of Si. The damage does not simply cause a surface layer of high‐recombination velocity, but rather tends to bend the Si band edges downwards, irrespective of the Si conductivity type.
118 citations
TL;DR: In this paper, the authors consider the evidence in support of the defect model and consider chemical reactions and interdiffusion effects which may occur when metals are deposited and the possible microscopic nature of the defects so formed and their influence on barrier formation.
Abstract: Over the years a number of different mechanisms have been proposed to account for Schottky barrier formation at metal–semiconductor interfaces. The application of modern surface analytical techniques to study such interfaces has recently shown that the influence of surface and near surface defects in the semiconductor, can, in many instances, dominate the mechanism of barrier formation. This is believed to be particularly true for metals on clean cleaved (110) surfaces of III–V semiconductors. In this article we consider the evidence in support of the defect model. We consider chemical reactions and interdiffusion effects which may occur when metals are deposited and we consider the possible microscopic nature of the defects so formed and their influence on barrier formation. We also consider experimental and theoretical studies when clean semiconductor surfaces are subjected to controlled contamination prior to the deposition of the metal contact and how these, in general, support the defect model.
75 citations
TL;DR: In this article, an exact solution of the transport equation in the space charge region and the effects of photogenerated majority carriers were derived for Schottky barrier, metal-insulator- semiconductor, or semiconductor-electrolyte junction solar cells.
Abstract: An equation for the collection efficiency (i.e., internal quantum efficiency) is derived that can be used for Schottky barrier, metal‐insulator‐ semiconductor, or semiconductor‐electrolyte junction solar cells. It is obtained from an exact solution of the transport equation in the space‐charge region and includes the effects of photogenerated majority carriers. It is shown that these carriers can diffuse to the interface and thereby oppose the minority‐carrier photocurrent by recombination or emission. This effect is shown to be quite significant in reducing the collection efficiency when the majority‐carrier mobility is low and at short wavelengths where the absorption coefficient becomes large.
73 citations
TL;DR: In this paper, the junction characteristics were found to be Schottky-like in the large sense accompanied by significant differences in detail, and the carrier mobility was concentration dependent on the carrier concentration.
Abstract: Rectifying barriers of undoped and lightly doped trans‐(CH)x films with low work function metals have been investigated. I‐V and C‐V measurements were used to explore the junction properties. The junction characteristics were found to be Schottky‐like in the large sense accompanied by significant differences in detail. Using C‐V measurements to determine the carrier concentration, we found the carrier mobility to be concentration dependent.
PARC1
TL;DR: In this article, the first report of a direct correlation of Schottky barrier characteristics to silicide growth on a •Si:H was given, showing that changes in diode ideality factor produced by annealing can now be directly attributed to growth of Pd2Si as demonstrated by Raman spectroscopy.
Abstract: This letter gives the first report of a direct correlation of Schottky barrier characteristics to silicide growth on a‐Si:H. Changes in diode ideality factor (from 1.2 to 1.05) produced by annealing can now be directly attributed to growth of Pd2Si as demonstrated by Raman spectroscopy. Unannealed samples show long‐term changes in characteristics at room temperature due to slow silicide growth. However, Pd Schottky barriers possess ideal stable characteristics once silicide growth is complete.
TL;DR: The Schottky-barrier energy φB of Pd contacts on InP, GaAs and Si were measured and the metallurgical behavior of the contact structures were studied using Auger electron spectroscopy as mentioned in this paper.
Abstract: The Schottky-barrier energy φB of Pd contacts on InP, GaAs and Si were measured and the metallurgical behavior of the contact structures were studied using Auger electron spectroscopy. A carefully processed set of samples were used to show conclusively that φB is greater on p-InP that on n-InP, unlike the behavior of GaAs and Si Schottky diodes fabricated at the same time with similar processing steps.
TL;DR: In this paper, the I-V and C-V data of Schottky devices formed on electrodeposited n-CdTe films were interpreted to determine the principle trap energy and density.
Abstract: The I–V and C-V data of Schottky devices formed on electrodeposited n-CdTe films are interpreted to determine the principle trap energy and density. The observed trap is an electron trap located at 0.55 eV below the conduction band with a density of ∼7 × 1015/cm3. This correlates well with the values reported for CdTe prepared by different methods. Nickel is found to be an injecting contact to electrodeposited CdTe films. Au/n-CdTe barrier height is determined to be 0.75–0.85 eV for Schottky devices.
TL;DR: In this paper, the Richardson constants for near-ideal Au and Al Schottky diodes have been determined from an analysis of forward current-voltage characteristics at different temperatures, taking into account the temperature dependence of the barrier height, the corrected value of the Richardson constant for AuGaAs diode is found to be very close to the predicted theoretical value.
Abstract: The Richardson constants for near-ideal AuGaAs and AlGaAs Schottky diodes have been determined from an analysis of forward current-voltage characteristics. Measurement of capacitance-voltage characteristics at different temperatures shows that the barrier heights of the diodes have very similar temperature dependence for both Au and Al contacts. On taking into account the temperature dependence of the barrier height, the corrected value of the Richardson constant for AuGaAs diode is found to be very close to the predicted theoretical value. The corresponding value for AlGaAs diode is about a factor of five smaller which is explained on the basis of a thin interfacial layer between Al and GaAs.
TL;DR: In this article, a set of epitaxial Al Schottky barriers were grown on molecular beam epitaxy AlxGa1−xAs layers without exposure to air.
Abstract: Epitaxial Al Schottky barriers were grown on molecular beam epitaxy AlxGa1−xAs layers without exposure to air. Al is deposited on As‐rich surfaces of AlxGa1−xAs form AlAs interfacial layers modifying the intrinsic Shottky barrier height. The difference between In‐AlGaAs and Al‐AlGaAs barrier heights agree well with their work function difference. Shottky barriers prepared on AlGaAs surfaces with the lowest As‐coverage obey the common anion rule in the region x⩽0.3. Above this value oxygen‐related elements appear to dominate.
TL;DR: In this paper, the ways of making silicide contacts to Si which have a contact depth of about 10nm are reviewed, and both high (0.85 to 0.75 eV) and low Schottky contacts have been demonstrated.
Abstract: Ways of making silicide contacts to Si which have a contact depth of about 10 nm are reviewed. Both Si alloys and refractory metal alloys have been explored for shallow silicide formation, and both high (0.85 to 0.75 eV) and low (0.50 to 0.40 eV) Schottky contacts have been demonstrated. Shallow contacts may not be uniform over the entire contact area due to nonuniform interfacial reaction, so nonuniform contacts consisting of a high barrier silicide and a low barrier silicide in parallel have been analyzed.
TL;DR: An experimental and theoretical study of both the capacitance and the conductance of Schottky and MIS tunnel diodes made on undoped SI:H, versus frequency, temperature, and voltage is presented in this article.
Abstract: An experimental and theoretical study of both the capacitance and the conductance of Schottky and MIS tunnel diodes made on undoped a‐SI:H, versus frequency, temperature, and voltage is presented in this paper. It is based on a general model using an equivalent electrical circuit of the devices, which permits an unambiguous distinction to be made between the contributions of bulk surface states, to determine their respective densities and to analyze their kinetic properties, It is shown that the bulk density of states (DOS) can be determined from capacitance and conductance measurements versus temperature and frequency on both Schottky and MIS devices, provided the modulation frequency is high enough to prevent any contribution from surface states. It is demonstrated that capacitance‐voltage characteristics of Schottky diodes cannot provide reliable information about either bulk or surface as the diffusion theory and not the thermionic theory is appropriate to describe the transport of electrons across th...
TL;DR: In this paper, the Schottky barrier was replaced with a SiO 2 layer underneath the gate, which improved the I-V characteristics of the gate but severely degraded the microwave performance of the FET.
Abstract: InP, and In 0.73 Ga 0.27 As 0.6 P 0.4 , and In 0.53 Ga 0.47 As lattice matched to InP are of special importance as active FET channel materials because of the high electron velocity and/or high electron mobility they offer. Using a AuGe/Ni/Au metallization system, specific contact resistances of 5 × 10-7Ω . cm2, 8 × 10-7Ω . cm2, and 5.8 × 10-6Ω cm2were obtained for ohmic contacts on In 0.53 Ga 0.47 As, InP, and In 0.89 Ga 0.11 As 0.24 P 0.76 , respectively. Leakage currents of 10 µA at 7-V reverse bias were observed for 1 × 200-µm gates on InP. and In 0.89 Ga 0.11 As 0.24 P 0.76 FET's having a SiO 2 film about 50 A thick under the gate. A thin SiO 2 layer underneath the gate improved the Schottky-gate I-V characteristics, but thick oxides severely degraded the microwave performance of the FET's. These excellent ohmic contacts and Schottky barriers resulted in a maximum insertion gain of 15 dB at 8 GHz and a noise figure of 2.5 dB with 8-dB gain at 7 GHz for the InP deviees. For 1.15-eV In x Ga 1-x As y P 1-y FET's, the resulting gain was 9 dB at 8 GHz.
TL;DR: In this paper, a two-dimensional electron gas (2 DEG) is accumulated at the interface of GaAs (n)/Al x Ga 1-x As (n) isotype heterojunctions.
Abstract: Previous works have shown that a two-dimensional electron gas (2 DEG) is accumulated at the interface of GaAs (n)/Al x Ga 1-x As (n) isotype heterojunctions. In this paper, a MESFET structure working with this 2 DEG is presented. Theoretical treatments are given, considering that the charge control results from the interpenetration of the Schottky space-charge region and the accumulation layer. A semi-analytical calculation is then developed: conductance, capacitance, source-to-drain current at saturation, and transconductance are predicted for a large-gate FET. Source-to-drain saturation current in short-gate FET is also given. Experimental results obtained in our laboratory and those recently published are compared to calculated data. The good agreement observed in all cases, including low-temperature measurements, clearly shows that the 2 DEG MESFET behavior is actually valid. The high mobility of electrons One can expect from the 2 DEG, particularly at 77 K, suggests that the 2 DEG MESFET is a promising device for microwave and high-speed devices.
TL;DR: In this paper, the Schottky barrier height was investigated in UHV-cleaved CdS and CdSe surfaces and metals spanning a wide range of chemical reactivity using UPS and XPS.
Abstract: Interfaces between UHV‐cleaved CdS and CdSe (1010) surfaces and metals spanning a wide range of chemical reactivity have been investigated using UPS and XPS. We have also probed the formation of Schottky barriers via J‐V and C‐V analysis, thus enabling a correlation of measured electrical transport properties with observed features of chemical reaction and interdiffusion. The experimental results reveal a systematic relationship between contact barrier heights and certain critical aspects of the reacted interface region, such as the stoichiometry of semiconductor outdiffusion and the extent of Cd cation dissociation from the reacted interface region. The use of reactive Al interlayers at noble metal contacts to control these aspects of contact formation, and hence the consequent Schottky barrier height, is demonstrated.
01 Jan 1981
TL;DR: In this article, the Schottky source and drain contacts with 300A PtSi were used to reduce the potential barrier arising in the gap between the source contact and the inversion channel.
Abstract: Recently MOSFET with Schottky source and drain has been considered an important candidate for VLSI because of its ultra-shallow junctions to minimize short-channel effects, low source and drain series resistances, simplified processes, and the elimination of minority carrier injection into the substrate [1]. We present results of MOSFETs with 300A PtSi as the source and drain contacts. The devices are fabricated on 2 × 1015cm-3, oriented n-Si substrates; and the gate oxide thickness is 250-300A. Long-channel behavior is observed for devices with channel lengths down to 1 µm, in very good agreement with the generalized guide for MOSFET miniaturization[2]. We observe that the output currents are smaller than those for the conventional MOSFETs. This is explained by the potential barrier arising in the gap between the Schottky source contact and the inversion channel. Extensive Arrhenius plots indicate that the gap has a profound effect in enhancing the corner field which in turn can greatly increase the current availability from the source. By reducing the gap to about 100A, the current approaches that as expected from the Pao-Sah theory[3].
TL;DR: In this article, an ICTS theory for a system of continuously-distributed gap states is given and experimental data by the ICTs applied to P-doped a-Si:H Schottky barrier diode are presented.
Abstract: An ICTS (Isothermal Capacitance Transient Spectroscopy) theory for a system of continuously-distributed gap states is given and experimental data by the ICTS applied to P-doped a-Si:H Schottky barrier diode are presented. It is shown that the ICTS is a useful tool for the study of gap states of a-Si:H whose material parameters are strongly temperature-dependent.
TL;DR: In this paper, three impact processes relevant to high-field electroluminescence are considered, namely ionization across the band gap, impurity ionization and impurity excitation.
Patent•
IBM1
TL;DR: In this article, a two-state memory cell with bipolar transistor and tunnel diode was proposed, where the bipolar transistor is kept on regardless of the tunnel voltage, which determines the zero or one state of the cell.
Abstract: A two state memory cell includes a bipolar transistor and a tunnel diode shunted across the base-collector junction thereof. A constant operating current is established through the transistor and the tunnel diode. The voltage across the tunnel diode may thus be maintained at one of two stable levels, while the bipolar transistor is kept on regardless of the tunnel diode voltage, which determines the ZERO or ONE state of the cell. Since the transistor is not switched on and off when the memory state (corresponding to the two tunnel diode voltage levels) changes, memory cell switching speed is not degraded by transistor switching delay. Moreover, since the current in the tunnel diode is maintained constant, preferably at a value midway between the tunnel diode peak and valley currents, the noise margin of the memory cell is enhanced and the possibility of false switching reduced. The tunnel diode/bipolar transistor combination may be formed on a semiconductor substrate as an integrated structure, thereby providing a high density memory cell.
TL;DR: In this article, a diffusion model for the collection efficiency of a SiHx Schottky-barrier solar cells is presented. But the model is not suitable for the short-wavelength response of these devices and suggests a way for improving their performance.
Abstract: A diffusion model for the collection efficiency of a‐SiHx Schottky‐barrier solar cells is found to be in excellent agreement with experimental data. This model accounts for the poor short‐wavelength response of these devices and suggests a way for improving their performance.
TL;DR: In this article, the Schottky picture of the metal-semiconductor interface was examined and it was shown that the appropriate metal work function is that of the metallic region closest to the silicon, i.e., the region most deviant from the bulk silicide.
Abstract: Recent studies of the initial stages of silicide formation on silicon have observed a chemical shift of silicide‐like valence orbitals. The sign of the shift suggests a silicon‐rich ’’silicide’’ close to the silicon substrate smoothly grading to the bulk silicide stoichiometry as the probed region is moved away from the substrate. Such results suggest a re‐examination of the boundary values appropriate to a simple Schottky picture of the metal‐semiconductor interface. It seems clear that the appropriate metal workfunction is that of the metallic region closest to the silicon‐i.e., the region most deviant from the bulk silicide. The absence of reliable experimental values for either stoichiometry or the workfunciton of this region forces us to model both. Assuming the silicon electron affinity and doping to be unaffected by the interface, we conclude that such a silicon excess would reduce the dependence of barrier height upon bulk metal (silicide) workfunction. Further, we conclude that if this metallic layer has a stoichiometry very silicon‐rich (∠(metal)Si4) the barrier height of most silicides would be fully explained by this effect and the Schottky picture of the interface.
TL;DR: In this paper, GaSb Schottky barrier photodiodes are shown to have quantum efficiency higher than 35 percent over a broad band of infra-red light wavelength shorter than 1.6 µm.
Abstract: GaSb Schottky barrier photodiodes are shown to have quantum efficiency higher than 35 percent over a broad band of infra-red light wavelength shorter than 1.6 µm. Theoretical calculations of current voltage characteristics including tunneling current are compared with the experiment and it is suggested that surface leakage current, tunneling current, and avalanche breakdown, respectively, dominate the reverse characteristics with increasing voltage. Epitaxial growth of an n-type layer with carrier density 1015cm-3and suitable surface passivation are key technologies for the application of this material to infra-red detectors.
TL;DR: A series of codeposited alloy films of Pt•Si with a composition changing from Pt75Si25 to Pt50Si50 and of Pd•Si changing from Pd75Si 25 to Pd67Si33 have been prepared on Si for a systematic study of shallow silicide contacts as mentioned in this paper.
Abstract: A series of codeposited alloy films of Pt‐Si with a composition changing from Pt75Si25 to Pt50Si50 and of Pd‐Si changing from Pd75Si25 to Pd67Si33 have been prepared on Si for a systematic study of shallow silicide contacts. The effects of alloy composition and heat treatment on the formation and properties of these contacts have been investigated by I‐V measurement of Schottky barrier height, glancing incidence x‐ray diffraction, and cross‐sectional transmission electron microscopy. Shallow contacts with a depth of about 10 nm and with the Schottky barrier height of PtSi and Pd2Si have been achieved.
TL;DR: In this paper, the diffusion equation for an illuminated Schottky barrier is solved for a finite lifetime of photoinjected minority carriers within the barrier, and the general solutions are related to parabolic cylinder functions when diffusivity and mobility are constant.
Abstract: The diffusion equation for an illuminated Schottky barrier is solved for a finite lifetime of photoinjected minority carriers within the barrier. The general solutions are related to parabolic cylinder functions when diffusivity and mobility are constant. These solutions are subject to the usual boundary conditions that at the surface the minority carrier current is proportional to the carrier density and that at the barrier/bulk interface the carrier density and its gradient are continuous. The photoconversion efficiency for a given impurity concentration is completely defined by three parameters: the charge transfer rate at the surface, the optical absorptivity, and the carrier lifetime. These calculations are applicable to many of the oxide semiconductors used as anodes in photoelectrolysis.