Showing papers on "Schottky barrier published in 1976"
TL;DR: In this article, it was shown that the effective height of a Schottky barrier can be controlled over a wide range using highly doped surface layers formed by low energy ion implantation.
Abstract: Using simplified models it is shown that the effective height of a Schottky barrier can be controlled over a wide range using highly doped surface layers. Experimental results on silicon having surface layers formed by low energy ion implantation verify the main features of the models and show that the use of surface layers brings flexibility to the Schottky barrier system.
272 citations
TL;DR: The Schottky barrier for holes on common III-V and II-VI semiconductors contacted by Au is shown to depend only on the anion electronegativity.
Abstract: The Schottky barrier for holes on common III-V and II-VI semiconductors contacted by Au is shown to depend only on the anion electronegativity.
196 citations
TL;DR: In this article, the Schottky barrier was used in thin-film amorphous-silicon solar cells and the current-voltage characteristics were studied in the range from 270 to 370°K and were found to be in agreement with the diffusion theory of metal-semiconductor rectification.
Abstract: Metal–amorphous‐silicon Schottky barriers, similar to those used in thin‐film amorphous‐silicon solar cells, exhibit nearly ideal diode behavior in the dark. The current‐voltage characteristics have been studied in the range from 270 to 370 °K and are found to be in agreement with the diffusion theory of metal‐semiconductor rectification. Barrier heights, which were measured by two different methods, depend on the metal work function, and barriers as high as ∼1.1 eV are obtained with Pt films.
189 citations
TL;DR: In this paper, the properties of d.c. sputtered molybdenum-silicon Schottky diodes are described and a model is proposed which is capable of explaining most features of the observed C-V and I-V characteristics.
Abstract: The properties of d.c. sputtered molybdenum-silicon Schottky diodes are described. Although it is possible to produce near ideal characteristics when a low sputtering voltage is used for a short time, increased voltage and time lead to significant deviation from the ideal. A model is proposed which is capable of explaining most features of the observed C-V and I-V characteristics. This model assumes that sputtering damage causes donor-like traps to be created close to the semiconductor surface. It is found that an exponential distribution of traps with characteristic length in the range 10–100 A and an energy level of 0·43 eV below the conduction band is sufficient to account for the observed characteristics. The modification to the I–V characteristics is due to tunnelling through the top of the Schottky barrier where it is narrowed by the presence of the excess trapped charge.
124 citations
TL;DR: In this paper, it was shown that current transport through Schottky barriers formed by Pd on n-type silicon with a thin thermally grown oxide is sensitive to hydrogen in the ambient.
Abstract: It is shown that current transport through Schottky barriers formed by Pd on n-type silicon with a thin thermally grown oxide is sensitive to hydrogen in the ambient. It is shown that a transition from minority- to majority-carrier dominated current occurs with increasing hydrogen pressure.
115 citations
TL;DR: In this article, the electrical and optical properties of Au-n-type silicon Schottky-barrier solar cells (SBSC) have been measured and it has been shown that the value of Voc is increased by up to 38% and the maximum conversion efficiency by as much as 35% when compared with cells having no grown oxide layer.
Abstract: Measurements have been made of the electrical and optical properties of Au–n‐type silicon Schottky‐barrier solar cells (SBSC) in which the metal and semiconductor are separated by a thin interfacial oxide layer ∼10–23 A thick. Measurements of the V‐I characteristics showed that the value of Voc is increased by up to 38% and the maximum conversion efficiency by as much as 35% when compared with cells having no grown oxide layer.
110 citations
TL;DR: In this article, a detailed analysis of the slow-wave propagation on Schottky-contact microstrip lines (SCMLs) is presented, including the effect of metallic losses.
Abstract: Schottky-contact microstrip lines (SCML) are a special type of transmission line on the semiconducting substrate: the metallic-strip conductor is specially selected to form a rectifying metal-semiconductor transition while the ground plane exhibits an ohmic metallization. Thus the cross section of SCML is similar to that of a Schottky-barrier diode. The resulting voltage-dependent capacitance per unit length causes the nonlinear behavior of such lines. In this paper a detailed analysis of the, slow-wave propagation on SCML is presented, including the effect of metallic losses. Formulas for the propagation constant and characteristic impedance are derived and an equivalent circuit is presented. Conditions for slow-mode behavior are given, particularly taking into account the influence of imperfect conductors and defining the range of many interesting applications. Experimental results performed on Si-SCML are compared with theory.
107 citations
TL;DR: In this paper, the Schottky barrier diodes fabricated from discharge-produced amorphous Si were used for electroluminescence in a 0.2-eV broad band.
Abstract: Electroluminescence has been obtained in forward‐biased p‐i‐n diodes, and also in Schottky barrier diodes fabricated from discharge‐produced amorphous Si. The emission at 78 °K in both electroluminescence and photoluminescence peaks at 1.28±0.08 eV in a 0.2‐eV broad band with an external quantum efficiency of ∼10−3.
106 citations
TL;DR: The barrier height of a Pd-CdS Schottky diode is reported to decrease markedly when exposed to hydrogen as mentioned in this paper, due to the decrease in Pd work function.
Abstract: The barrier height of a Pd‐CdS Schottky diode is reported to decrease markedly when exposed to hydrogen. This effect is believed to be due to the decrease in Pd work function. It makes a good simple hydrogen detector (even at 298 °K) over the range 500–5000 ppm H2.
103 citations
TL;DR: In this article, the formation of Schottky barriers between Si(111) 7 and group-III metals has been studied by ultraviolet photoemission spectroscopy, and a two-step empirical model is proposed for the formation.
Abstract: The formation of Schottky barriers between Si(111) 7 \ifmmode\times\else\texttimes\fi{} 7 and group-III metals has been studied by ultraviolet photoemission spectroscopy Modifications of the band bending and of the work function occur for low values of metal coverage (one to four monolayers) The "intrinsic," clean surface states are simultaneously replaced with "extrinsic" metal-related interface states A two-step empirical model is proposed for the formation of the barrier The first step is saturation of interface bonds, and the second step, critical in determining the junction properties, corresponds to the formation of a thin region with properties intermediate between that of a metal and of a semiconductor Our experiments emphasize the need for a detailed theoretical treatment of the interface chemical bonds and underline the inadequacy of "macroscopic" models for metal-semiconductor junctions
99 citations
TL;DR: In this article, critical point structures in Schottky-barrier electroreflectance spectra of Ga3dV-sp3 conduction band transitions in the 20-22eV range were shown to lie approximately 170±30 meV below the X6C minima in GaAs.
Abstract: Resolved critical point structures in Schottky-barrier electroreflectance spectra of Ga3dV-sp3 conduction band transitions in the 20-22-eV range provide a direct proof that the L6C equivalent minima lie approximately 170±30 meVbelow the X6C minima in GaAs. This ordering, opposite to that assumed and apparently supported by previous experiments, is in fact consistent with these experiments and provides natural explanations for many formerly puzzling features of GaAs.
TL;DR: In this article, the electroabsorption coefficient of GaAs has been measured in uniform electric fields at wavelengths from 0.91 to 0.93 μm using Schottky barrier contacts on low-loss GaAs waveguides consisting of high purity epitaxial GaAs grown on heavily doped GaAs substrates.
Abstract: The electroabsorption coefficient of GaAs has been measured in uniform electric fields at wavelengths from 0.91 to 0.93 μm. These measurements were made using Schottky barrier contacts on low‐loss GaAs waveguides consisting of high‐purity epitaxial GaAs grown on heavily doped GaAs substrates. The experimental results are in good agreement with theoretical calculations of the Franz‐Keldysh effect. Electroabsorption detectors with subnanosecond response time and 100% internal quantum efficiency have been integrated into these waveguides. Small values of avalanche gain have been obtained without any intentional guard‐ring structure. Integrated electroabsorption modulators with greater than 20‐dB depth of modulation were also fabricated.
TL;DR: In this article, the authors used backscattering of energetic 4He+ ions to study the composition and depth profile of silicide layers formed when thin nickel films evaporated on (111) and (100) silicon surfaces are heated in a nitrogen-hydrogen ambient.
Abstract: Rutherford backscattering of energetic 4He+ ions has been used to study the composition and depth profile of silicide layers formed when thin nickel films evaporated on (111) and (100) silicon surfaces are heated in a nitrogen-hydrogen ambient. In the temperature range 297 to 430 degrees C two phases are seen to form sequentially. The growth of the first phase, Ni2Si, is parabolic with time, whilst the second, NiSi, grows linearly with time. The simultaneous presence of both diffusion and reaction-rate-limiting mechanisms is implied by the parabolic and linear growth laws. An investigation of the electrical characteristics of diodes which were metallized and heat-treated simultaneously shows little change in the barrier height.
TL;DR: Capacitance-voltage characteristics have been obtained for Schottky barrier diodes, formed on polished surfaces of natural p-type semiconducting diamond, before and after illumination with radiation capable of neutralizing ionized donors in the depletion layer as mentioned in this paper.
Abstract: Capacitance-voltage characteristics have been obtained for Schottky barrier diodes, formed on polished surfaces of natural p-type semiconducting diamond, before and after illumination with radiation capable of neutralizing ionized donors in the depletion layer. Plots of 1/C2 versus V for the two cases have yielded values for both the acceptor concentration NA and the donor concentration ND. Comparison of these data with those obtained from Hall effect measurements indicate that the latter overestimate the value of NA-ND by almost a factor of 2. The boron concentration has been determined in approximately the same surface layer as the capacitance measurements by detecting the alpha -particles emitted during irradiation with 700 keV protons using the reaction 11B(p, alpha 1)8Be* to 2 alpha 2. A quantitative correlation has been obtained between the boron and acceptor concentrations.
TL;DR: In this article, the Schottky barrier for holes on common III-V and II-VI semiconductors contacted by Au is shown to depend only on the anion.
Abstract: The Schottky barrier for holes on common III–V and II–VI semiconductors contacted by Au is shown to depend only on the anion. Compilation of the experimental data shows that compound semiconductors with the same anion but different cations possess very similar values for the the Au Schottky barrier for holes. Further, the data show that the Pauling electronegativity of the anion provides a useful ordering parameter for the height of the Schottky barrier. This correlation is compared with analogous barrier data on rocksalt and layer structures as well as earlier results for the semiconductor–vacuum interface.
TL;DR: In this paper, the thermal reaction of a vacuum-evaporated Ti film with substrate GaAs has been investigated using Auger electron spectroscopy and x-ray diffractometry.
Abstract: The thermal reaction of a vacuum‐evaporated Ti film with substrate GaAs has been investigated using Auger electron spectroscopy and x‐ray diffractometry. As accumulation and Ga depletion at the Ti/GaAs interface and Ga pileup in front of the As‐rich layer have been observed. The As‐rich and the Ga‐rich layers have been found to be composed of TiAs/Ti5As3 and Ti2Ga3/Ti5Ga4, respectively. It has also been found that the rate of the Ti‐GaAs reaction is governed by the interdiffusion process of Ti and As at the interface with an activation energy of 1.70±0.05 eV. The low diffusivity and relatively high Schottky barrier height of the present system facilitate the formation of useful Schottky barrier junctions.
TL;DR: In this article, a model for the drain conductance of J-FET's in the hot electron range is proposed based on a physical picture revealed through two-dimensional numerical analysis, which shows that the electron concentration changes gradually at the boundary of a depleted region which is defined by a conventional theory.
Abstract: A new model is proposed for the drain conductance of J-FET's in the hot electron range. The model is based on a physical picture revealed through two-dimensional numerical analysis. The two-dimensional analysis shows that the electron concentration changes gradually at the boundary of a depleted region which is defined by a conventional theory. Because of this gradual change, electrons can remain after the pinch-off and contribute to the drain current. Although the high electric field causes the electron velocity to saturate, the drift velocity vector rotates into the x axis (source-to-drain) with the increase in the drain voltage. The increase in the x component V x of the drift velocity gives rise to a small increase in drain current, that is, a finite drain conductance. The proposed model takes into account the above two essential features, gradual change in electron distribution, and the rotation of the velocity vector. This model is constructed in a single formulation which describes the current-voltage characteristics from the linear to the saturated drain-current region. Theoretical calculations agree quite well with the experiment on GaAs Schottky barrier gate FET's.
TL;DR: In this paper, the authors evaluated the performance of Schottky-barrier diodes operating in the thermionic mode by applying the laws of vacuum tube electronics to the space charge region and by incorporating the treatment of the series-resistance effect into the discussion.
Abstract: Transit‐time and series‐resistance effects in heavily doped Schottky‐barrier diodes operating in the thermionic mode are evaluated by applying the laws of vacuum tube electronics to the space‐charge region and by incorporating the treatment of the series‐resistance effect into the discussion. It is assumed that the field distribution in the space‐charge region is linear, that collisions in the space‐charge region can be neglected, and that the signals are so small thatr the equations of motion can be linearized. The case of uniform field distribution is also briefly dealt with; the results are not significantly different from the linear field case. At a frequency equal to three times the plasma frequency of the bulk semiconductor the detection and mixing efficiency is about 0.25 times the low‐frequency value. The effect of the high‐frequency conductance of the space‐charge region turns out to be quite small when the series‐resistance effect is taken into account; the performance is then determined by a single transit‐time factor ‖g (jω) ‖2 and a series‐resistance factor that is independent of transit time. The effect of tunneling on the device performance is discussed briefly. Satisfactory detection and mixing performance seems feasible for the 10–40‐μm wavelength range.
TL;DR: In this article, a new nuclear Betavotaic battety is described, which uses a Schottky barrier in place of the more standard p-n junction diode, along with 147Pm metal film rather than Pm2O3 oxide as in the commercially available Betacel.
Abstract: A new nuclear betavotaic battety is described. It uses a Schottky barrier in place of the more standard p-n junction diode, along with 147Pm metal film rather than Pm2O3 oxide as in the commercially available Betacel. Design details of the battery including measurement of absorption, conversion efficiency, thickness etc. as functions of & resistivity and other cell parameters are described. A prototype design is discussed and its performance assessed.
TL;DR: In this article, the electronic structure of vacuum and metal-semiconductor interfaces was studied using a method involving self-consistent pseudopotentials, and the Schottky barrier heights were calculated in good agreement with experimental results.
Abstract: The electronic structure of vacuum–semiconductor and metal–semiconductor interfaces has been studied using a method involving self‐consistent pseudopotentials. Our model for an intimate metal–semiconductor interface consists of jellium in contact with a semiconductor described in the pseudopotential formalism. Local density of states and charge densities are used to analyze the electronic properties of the two types of interfaces. For the vacuum–semiconductor case, Si (111) surfaces and the (110) surfaces of III–V and II–VI zincblende semiconductors are investigated, with GaAs and ZnSe considered as zincblende prototypes. For metal–semiconductor interfaces, jellium of Al density in contact with (111) surfaces of Si and the (110) surfaces of GaAs, ZnSe, and ZnS are investigated. The calculated Schottky barrier heights are in good agreement with experimental results. It is shown that the variations in the experimental barrier height for different metals in contact with various semiconductors can be understo...
Patent•
30 Jul 1976TL;DR: In this article, the Schottky barrier was used to make an ohmic contact between the amorphous silicon and the substrate, where the doping concentration of the first layer is graded so the dopant concentration is maximum at the interface of the second layer and substrate.
Abstract: A first layer of semiconductor device is of doped amorphous silicon prepared by a glow discharge in a mixture of silane and a doping gas. The first layer is on a substrate having good electrical properties. On the first layer and spaced from the substrate is a second layer of amorphous silicon prepared by a glow discharge in silane. On the second layer opposite the first layer is a metallic film forming a surface barrier junction therebetween, i.e. a Schottky barrier. The first layer is doped so as to make an ohmic contact with the substrate. Preferably the doping concentration of the first layer is graded so the dopant concentration is maximum at the interface of the first layer and the substrate. In a second embodiment of the Schottky barrier semiconductor device an intermediate layer is between and contiguous to both the first layer and the substrate. The intermediate layer facilitates in making ohmic contact between the amorphous silicon and the substrate. Annealing and heat treating steps are performed in the fabrication of the Schottky barrier device to increase device efficiency.
TL;DR: The Schottky barrier heights for Au, Al, and Ba on diamond are reported in this article, and the variation of the barrier energy with metals is found to be small.
TL;DR: The GSCH model for surface states on (110) GaAs proposed by Gregory et al. appears (based on a wide range of results) to apply to all faces of all III-V semiconductors as mentioned in this paper.
Abstract: The GSCH model for surface states on (110) GaAs proposed by Gregory et al. appears (based on a wide range of results) to be well established and to apply to all faces of all III–V semiconductors. In this model, the filled and empty surface states are associated with and localized on the column V and III atoms, respectively, and a band gap (greater than 1 eV) separates the filled and empty surface states. For example, detailed studies of GaAs and InP locate the bottom of the empty states at 0.7 and 0.25 eV, respectively, below the conduction band minimum (CBM), whereas in GaSb it lies above the CBM. The filled states in all three cases are located well below the valence band maximum (VBM). In the context of the GSCH model, the details of the first steps in oxidation and formation of Schottky barrier with Cs have been examined experimentally. It is concluded from studies of Ga and As chemical shifts by Pianetta et al. that, in the first step of oxidation, the oxygen gains electrons from As but not the Ga su...
TL;DR: In this article, the Schottky barrier height (φB) of the silicide film on n-type silicon increases from that of NiSi•nSi to PtSi−nSi with increasing amount of Pt in the NiPt films.
Abstract: Metal silicides such as PtSi and NiSi have important applications in silicon integrated circuit technology as rectifying or Ohmic contacts. With a view to obtaining contacts with Schottky barrier heights adjustable between those of NiSi and PtSi, silicides were formed in NiPt alloy films with varying concentrations of Ni and Pt. The metal films were sputter deposited sequentially from Ni and Pt targets and also from a single alloy target containing 15 wt% Pt. Silicides were formed by sintering at 475 °C for 20 min. The depth‐compositional profiles of these films were obtained by Auger electron spectroscopy (AES) coupled with Ar+ ion sputtering. The effects of the sintering and the presence of oxygen impurity on the composition profiles are discussed. The chemical effects observed in the Auger spectra from the silicides are presented. The Schottky barrier height (φB) of the silicide film on n‐type silicon increases from that of NiSi‐nSi to PtSi‐nSi with increasing amount of Pt in the NiPt films. The variat...
TL;DR: In this article, a general model for the analysis of metal-semiconductor solar cells is presented, which takes into account the cell optical properties, carrier recombination effects, semiconductor minority carrier properties, series resistance, cell thickness, and active surface area.
Abstract: A general model for the analysis of metal‐semiconductor solar cells is presented. The model takes into account the cell optical properties, carrier recombination effects, semiconductor minority‐carrier properties, series resistance, cell thickness, and active surface area. Numerical methods are used to solve the appropriate continuity equations and hence compute the photocurrent density under AMO conditions. The operation of the model is demonstrated using p‐ and n‐type Si and GaAs with Au being taken as the barrier metal. Calculations are presented showing the effect on solar energy conversion efficiency of surface recombination velocity, barrier height, minority‐carrier lifetime, barrier metal thickness, collecting grid configuration, and cell thickness. A comparison of practical and computed data for the Au/n‐GaAs system yields good agreement.
TL;DR: In this article, the spectral response of Schottkyd diodes at short wavelengths was analyzed for photovoltaic solar cells and it was shown that a reasonable percentage of the available carriers can be collected even when the diffusion lengths are much smaller than this.
Abstract: The collection efficiency for carriers optically generated in the depletion region of photovoltaic solar cells is analyzed. For p‐n junction devices, it is shown that virtually all these carriers are collected provided the minority carrier diffusion lengths are larger than the width of the depletion layer, and that a reasonable percentage will be collected even when the diffusion lengths are much smaller than this. For Schottky diode devices, the collection efficiency for carriers optically generated near the metal‐semiconductor interface is shown to be small and to depend critically upon the exact model of the contact used. As a consequence the spectral response of Schottky diodes at short wavelengths is shown to contain considerable information regarding the physics of the metal‐semiconductor contact. New surface insulator devices are shown to have a short‐wavelength response superior to that of Schottky diodes.
TL;DR: In this paper, the series resistances of some devices can be reduced significantly, thus effecting increases in the cutoff frequencies, and the resistance swing of Schottky diodes can also be raised.
Abstract: The fabrication of ultra-thin silicon membranes of micron or submicron sizes with thicker supporting frames makes possible improvements in several kinds of electronic devices. We show that the series resistances of some devices can be reduced significantly, thus effecting increases in the cutoff frequencies. The resistance swing of Schottky diodes can also be raised. Initial experimentation relating to some of these applications is presented.
Patent•
09 Apr 1976TL;DR: In this article, a plurality of Schottky barrier devices are produced by a method which uses a relationship between barrier height, surface concentration of impurities, and alloying time valid when a thin layer of oxide is present on a device substrate.
Abstract: A plurality of Schottky barrier devices are produced by a method which uses a relationship between barrier height, surface concentration of impurities, and alloying time valid when a thin layer of oxide is present on a device substrate and includes the steps of preselecting an impurity concentration for the principal surface of a plurality of silicon substrates and using a predetermined alloying time for each substrate to achieve a preselected barrier height.
TL;DR: In this article, the results of an experimental study of the interdiffusion occurring at elevated temperatures in Au/GaAs and Ni/Au-Ge/GAAs thin-film systems and the corresponding changes in the Schottky barrier energy φBn are presented.
Abstract: The results of an experimental study of the interdiffusion occurring at elevated temperatures in Au/GaAs and Ni/Au–Ge/GaAs thin‐film systems and of the corresponding changes in the Schottky barrier energy φBn are presented. Composition‐depth profiles obtained with Auger electron spectroscopy and in situ sputter etching are used to observe the interdiffusion behavior. For Au/GaAs samples, significant Ga outdiffusion and surface accumulation is found along with appreciable lowering of φBn with increasing heat treatment. For an ohmic contact consisting of Ni/Au–Ge/GaAs, Ni moves through the Au–Ge layer to produce an increase in φBn at temperatures below the Au–Ge eutectic point. Considerable intermixing of all constituents of the Ni/Au–Ge/GaAs system is found to occur above the Au–Ge eutectic temperature.