Showing papers on "Doping published in 1974"

Micro-structure field emission electron source

Abstract: A new and improved microminiature field emission electron source and method of manufacturing is described using a single crystal semiconductor substrate. The substrate is processed in accordance with known integrated microelectronic circuit techniques to form a plurality of integral, single crystal semiconductor raised field emitter tips at desired field emission cathode sites on the surface of the substrate in a manner such that the field emitter tips are integral with the single crystal semiconductor substrate. An insulating layer and overlying conductive layer may be formed in the order named over the semiconductor substrate and provided with openings at the field emission site locations to form micro-anode structures for each field emitter tip. By initially appropriately doping the semiconductor substrate to provide opposite conductivity-type regions at each of the field emission sites, and appropriately forming the conductive layer, electrical isolation between the several field emission sites can be obtained.

Relationship between resistivity and phosphorus concentration in silicon

Abstract: Accurate electrical and analytical measurements allowed us to determine a relationship between resistivity and phosphorus concentration in doped silicon. This relationship is compared with that obtained by other authors in the case of n‐type silicon, and the differences due to the various doping agents are discussed. Differences between concentrations determined by analytical techniques and by Hall effect measurements are reported.

Lattice parameter study of silicon uniformly doped with boron and phosphorus

Abstract: Powder and single-crystal X-ray techniques have been employed to obtain precise lattice parameters of silicon uniformly doped with boron or phosphorus. Good agreement is found between the two methods. Previous accurate determination of the CuKα1, effective wavelength has yielded λ=1.540621±0.000006 A. Particular care has been devoted to the chemical and electrical characterization of the alloys, whose maximum dopant concentrations were 8×1019 atoms cm−3 for P and 4.4×1020 atoms cm−3 for B.

Nozzles formed in monocrystalline silicon

Abstract: Method for producing a predetermined pattern of small size fluid nozzles of identical or different geometries in crystallographically oriented monocrystalline silicon or similar material utilizing anisotropic etching through the silicon to an integral etch resistant barrier layer heavily doped with P type impurities.

Interface and doping profile characteristics with molecular‐beam epitaxy of GaAs: GaAs voltage varactor

Abstract: Studies of the doping profile characteristics of molecular‐beam epitaxy (MBE) of GaAs on GaAs substrates are reported. Highly resistive regions at the substrate—epitaxial‐layer interface, and within the epitaxial layer, may occur if the growth is interrupted. It is shown that almost any arbitrary voltage dependence of the capacitance of such structures can be achieved by varying the dopant deposition rate during epitaxy. To illustrate the versatility of this growth technique, voltage‐variable capacitors have been prepared with Schottky barriers on MBE GaAs layers with precisely controlled doping profiles. Low‐frequency measurements (up to 100 MHz) demonstrate that capacitance variations in excess of a factor of 10 have been achieved by varying the applied bias voltage V from 0.3 V (with no significant forward conduction) to −1.0 V. The feasibility of frequency tuning diodes with C−1/2[sine wave]φ−V, where φ is the effective barrier height, is shown. At ‐3 V bias, cutoff frequencies >40 GHz have been measu...

Method of forming doped dielectric layers utilizing reactive plasma deposition

Abstract: A doped oxide layer is formed on a semiconductor substrate utilizing reactive plasma deposition. Impurity doped thin film oxide deposits are formed by reacting suitable source gases in an RF plasma at low pressures and temperatures. Passing an dopant compound in vapor form with a suitable carrier gas, in combination with a flow of silicon hydride and an oxide vapor flow, provides a solid film of doped silicon dioxide on a surface when the gases are subjected to an RF discharge. The method features low temperature processing which is particularly advantageously utilized in providing a doped oxide layer as a diffusion source for a Group III-V substrate.

Electron lifetime and diffusion constant in germanium-doped gallium arsenide

Abstract: The lifetime of electrons in Ge‐doped p‐type GaAs grown by liquid phase epitaxy has been determined as a function of doping level using an optical phase‐shift technique. The internal radiative efficiency of this material is found to be high even at room temperature. Furthermore, the electron lifetime τ has been measured in Ge‐doped samples compensated with Sn donors. Data are presented both for 300°K and 77°K. Measurements of the diffusion length on the same samples are also presented. From the combined results the diffusion constant of the electrons is obtained as a function of doping level both for the Ge‐doped and the Ge‐doped Sn‐compensated samples. In GaAs doped with Ge only, τ at 300°K is inversely proportional to the hole concentration p; at this temperature partial compensation with Sn donors has only an effect at higher hole concentrations. At 77°K, the τ values depend more strongly on the degree of compensation. Conclusions regarding the influence of band tailing are presented.

Raman study of the interaction between localized vibrations and electronic excitations in boron-doped silicon

Abstract: The Raman spectrum of localized boron vibrations in heavily doped silicon is studied as a function of exciting laser frequency. The resulting line shapes are markedly asymmetric and show a pronounced dependence on the frequency of the exciting laser line. These results are explained as Fano-type interference between a continuum of Raman-active electronic excitations due to the free holes and the discrete localized-mode vibronic scattering. This effect is compared to the influence of free holes in the Raman spectrum of the zone-center optical phonon. From this comparison, conclusions as to the effect of the boron impurities on the electronic band structure are drawn and some deformation potentials associated with the localized vibrations are estimated.

Characterization of the Transport Properties of Halogen-Doped CdTe Used for Gamma-Ray Detectors

Abstract: The mobilities, trapping times, activation energies, and trap concentration have been measured for both holes and electrons in Br and Cl-doped CdTe using the time-of-flight technique. Two electron traps 25 and 50 meV below the conduction band and two hole traps 140 and 350 meV above the valence band have been found. The 10 times larger concentration of levels found in the Br-doped CdTe can be explained using a model that describes the association of cadmium vacancies and substitutional halogens. The physical interpretation of the ??+ product when two levels are present is discussed for this case where the mobility is reduced and the lifetime is increased by trapping-detrapping phenomena. The measurements demonstrate that the material has excellent potential for ?-ray detectors that do not polarize with the proper surface preparation and make good detectors (6 keV FWHM for 122 keV ?-ray).

Breakdown behavior of rectifiers and thyristors made from striation-free silicon

Abstract: Taking advantage of the nuclear reaction30Si(n,γ)31Siβ-→31P, silicon was doped with phosphorus The resistivity was set to values between 2 and 200 Ωcm The measured resistivity profiles show the macroscopically homogeneous distribution of the dopant Photographs of the breakdown radiation emitted from diodes show that the silicon is also free from striation-like microvariations of the resistivity The diodes and thyristors prepared from the homogeneously doped silicon had blocking capabilities between 400 and 5200 V

The work function difference of the MOS-system with aluminium field plates and polycrystalline silicon field plates

Abstract: The work function difference of the AlSiO 2 Si-system was measured by the MOS-capacitance-voltage technique for n - and p -type silicon as substrate and was compared to the results obtained by different authors applying the photoemission technique. It could be seen that the work function differences measured in this work differ largely from the values measured by the photoemission technique. On the basis of the results obtained the work function differences of the p + polySiSiO 2  nSi - and n + polySiSiO 2  p Si-system were defined by comparative measurements. From this it was evident that the location of the Fermi level in heavily doped polycrystalline silicon is identical to the location of the Fermi level in monocrystalline silicon of the same impurity concentration.

Determination of deep trap levels in silicon using ion-implantation and CV-measurements

Abstract: Differential capacitance measurements on Schottky barrier contacts are used to determinedeep energy levels for 29 different impurities implanted into silicon. Back-ground doping and deep levels are separated by making use of the sharply peaked implantation distribution. Donor or acceptor behavior is identified by the shape of the measured apparent charge profile. Energy levels measured for many impurities after annealing of the radiation damage agree with values known from literature. Other levels are caused by a non-thermal state of incorporation into the silicon lattice, e.g. for C, Si, and Ge, even after annealing of the radiation damage. Some impurities, e.g. Nb, Ni, Ti, and Na, show more than one state of incorporation, concentrations of which vary with the annealing conditions. Many implanted elements, especially those having a low solubility, e.g. Au, Be, Co, Se, etc., show strong out-diffusion and precipitation at the surface at annealing temperatures around 500°C.

On heavy doping effects and the injection efficiency of silicon transistors

Abstract: A study of heavy doping effects on the current gain of diffused bipolar silicon transistors is continued, with emphasis on the variation of the current gain with injection level. The sensitivity of the calculations to some assumptions and approximations made previously is appraised. Numerical solutions of the heavy doping model simultaneously with the carrier transport equations are included.

Electrical and optical properties of thin films of Pb2+‐ and Si4+‐doped YIG produced by liquid phase epitaxy

Abstract: Thin films of Si4+‐doped YIG have been grown on Gd3Ga5O12 substrates by liquid phase epitaxy. The electrical resistivity, the sign of the Seebeck coefficient, and the optical transmission have been measured for a number of films prepared from the same melt at different growth temperatures in the range 780–960°C. The measurements show a high optical absorption for films prepared at low growth temperatures, while at intermediate temperatures there is a change from p‐type to n‐type conduction. A resistivity maximum and minimum in the optical absorption are also found. The results are discussed in terms of the charge‐compensation mechanism that occurs as Pb2+ ions are incorporated from the flux into the films at the lower growth temperatures. It is found that intrinsic donors, probably oxygen vacancies, are present in concentrations up to 0.03 per formula unit. The increase in the optical absorption coefficient, Δα, relative to pure YIG, is proportional to the concentration of nonionized holes, [p], i.e., Δα=...

Solid‐phase transport and epitaxial growth of Ge and Si

Abstract: Epitaxial growth of a semiconductor film from solid solution by dissolution and transport of an evaporated semiconductor layer through a metal film has been demonstrated. A Ge growth layer of 4800 A has been obtained by heating the system bulk‐Ge/Al/evaporated‐Ge at 300 °C. Electrical measurements indicate that the layers are heavily doped p type. A silicon growth of 2000 A has been obtained by heating the system bulk‐Si/Pd/evaporated‐Si at 600 °C. Channeling measurements show that the Ge and Si layers are well ordered and epitaxial with the underlying substrate.

Theoretical calculations of the Fermi level and of other parameters in phosphorus doped silicon at diffusion temperatures

Abstract: Taking into account the heavy doping effects (i.e., band tailing and impurity band formation) and high temperature effects, the Fermi level in lightly and heavily compensated phosphorus doped silicon, at normal diffusion temperatures is calculated numerically from the charge neutrality condition. The effective intrinsic carrier concentration is a function of the doping level and of the degree of compensation. Above discussed impurity concentration dependent results are used to calculate the impurity activity coefficient, the vacancy activity coefficient, and the concentration of the total number of vacancies as a function of doping and temperature.

Ionic and Electronic Conductivity in Y[sub 2]O[sub 3]-Doped Monoclinic ZrO[sub 2]

Abstract: The electronic and ionic conductivities of ZrO/sub 2/ were determined as a function of temperature, oxygen partial pressure, and trivalent dopant content. Observations were in reasonable agreement with the proposed defect structure model. Ionic conductivity for undoped zirconia was attributed to doubly ionized oxygen interstitials at high oxygen pressures and to doubly ionized oxygen vacancies at the lower extreme of the oxygen partial pressure. Doped zirconia, contrary to the undoped sample, showed maximum ionic transport at intermediate oxygen pressures. The ionic conductivity, due to extrinsic dopant effects, increased by increasing the amount of dopant and its range extended over a wider oxygen partial pressure. The observed decrease in activation energy for ionic condnctivity upon doping was attributed to the formation of anion vacancies whose concentration is directly proportional to the dopant contert. The 1 mole percent Y/sub 2/O/sub 3/ sample showed predominant ionic transport. (13 figures, 24 references) (auth)

Properties of Ge-doped GaAs and Al x Ga 1-x As, Sn-doped Al x Ga 1-x As and Si-Te-doped GaAs

Abstract: In order to better understand the electrical and optical properties of GaAs and AlxGa1-x As used in making double heterojunction lasers, we have studied the Hall coefficient, resistivity and photoluminescence behavior of doped epitaxial samples of these materials. In particular, we report results on Ge-doped GaAs and Alx Ga1-x As, Sn-doped AlxGa1-x As and Si-Te-doped GaAs single crystal layers which were grown on GaAs substrates by the liquid phase epitaxial method. The effects of impurities in the solution on the carrier concentration, mobility, photoluminescence spectra and possible recombination processes in these layers are discussed.

Method of making an insulated gate field effect transistor

Abstract: An improved insulated gate field effect transistor is achieved by using a material such as silicon nitride as an ion implantation and oxidation mask overlying a channel region, forming source and drain regions or extensions thereof by implanting ions of a conductivity modifier into a semiconductor substrate, and subjecting the implanted ions to a drive-in diffusion whereby the conductivity modifier ions are redistributed. The ion implantation allows greater control over the amount of conductivity modifier implanted in the lightly doped source and drain regions, the more uniform distribution of conductivity modifier increases the source-drain breakdown voltage, while the use of the silicon nitride mask provides simultaneously for general alignment of the channel region with the effective gate length.

The application of the loop annealing technique to self diffusion studies in silicon

Abstract: The loop annealing technique has been applied to the study of self diffusion in silicon over a wide range of doping concentrations. The results show that the diffusion coefficient decreases as the concentration of n-type dopant decreases and the concentration of p-type dopant increases. At a fixed temperature, the diffusion coefficient is linearly dependent on the electron concentration and this behaviour is in accord with the point defects responsible for self diffusion behaving as acceptors. The values obtained for the self diffusion coefficient in intrinsic material are in good agreement with those obtained by other workers at higher temperatures using profiling techniques and indicate a slight curvature in the Arrhenius plot.

Dielectric isolation process

Abstract: A method of epitaxially depositing onto a semiconductor substrate by planarizing the deposition surface of the substrate substantially parallel to a predetermined crystallographic plane, forming a deposition mask which exposes a predetermined site on the surface of the substrate, and epitaxially depositing semiconductor material in a preferred growth direction at the exposed site to produce a monocrystalline structure A plurality of sites may be exposed through the deposition mask to permit formation of a plurality of discrete monocrystalline structures having predetermined spacing Layers of different conductivity types can be formed in the structures by selective doping during deposition Monocrystalline structures formed by the above method may be coated with a dielectric material and further processed to produce semiconductor devices for use in integrated circuits If the monocrystalline structures are suitably arrayed and of a different conductivity type than the substrate, thus yielding semiconductor diodes, they can be utilized as a target in a vidicon tube

Auger and ellipsometric study of phosphorus segregation in oxidized degenerate silicon

Abstract: Phosphorus redistribution during thermal oxidation of degenerately doped silicon was investigated using Auger electron spectroscopy and ellipsometry. Concentration profiles were determined with a combination of chemical and sputter etching techniques. A substantial phosphorus pileup was observed in the oxide in a thin layer near the ellipsometrically determined Si–SiO2 interface. Calibrated against standards of known concentration, this layer was found to contain ∼2×1021 phosphorus atoms/cm3, independent of the oxidation temperature between 850 and 1000 °C.

Investigation of silicon carbide single crystals doped with scandium

Abstract: Doping processes of silicon carbide crystals with scandium are investigated. It is shown that the scandium solubility in SiC is limited within the 1800 to 2600°C temperature range and amounts to (2 to 3) × 1017 cm−3. On doping silicon carbide crystals with scandium the VLS growth mechanism is possible. The luminescence spectra of the crystals are studied. It is found that nitrogen actively affects the luminescence intensity of silicon carbide doped with scandium. The depth of the radiative recombination centre in SiC (Sc) which is acceptor like is found to be 0.24 eV. [Russian Text Ignored].

Hetero-Epitaxial Growth of Boron Monophosphide on Silicon Substrate Using B2H6-PH3-H2 System

Abstract: Boron monophosphide (BP) was epitaxially grown on Si substrates with (100), (110) and (111) faces, by thermal decomposition of a B2H6-PH3 mixture in hydrogen in the temperature range of 950°C to 1050°C. The crystallographic orientation of the BP was the same as that of the Si substrates. n- and p-type BP were obtained under different growth conditions. The carrier concentrations without any additional doping were from 1018 to 1021 cm-3 and their mobilities were from 150 to 80 cm2/Vsec.

Spatial dependence of the carrier lifetime in thin films of silicon on sapphire

Abstract: An experimental technique is described for determination of the generation carrier lifetime as a function of the distance of the insulator‐semiconductor interface. This method is applied to thin films of silicon on sapphire nominally 1 μ thick and doped n type.

Dielectric optical waveguides

Abstract: Dielectric optical waveguides can be made having a core of vitreous silica doped with nitrogen in the form of silicon nitride, and a cladding of pure vitreous silica. Silicon nitride may be present in the core material in quantities varying between .1% to 10% by weight. The silicon nitride doped silica glass can be formed in a boule by passing a mixture of gaseous compounds containing silicon and nitrogen through a induction coupled plasma discharge. The outside of the doped silica boule may be oxidized to reduce the nitrogen content.

Theoretical optimization of the thermoelectric figure of merit of heavily doped hot-pressed germanium-silicon alloys

Abstract: The theoretical variation of the thermoelectric figure of merit of heavily doped polycrystalline hot-pressed germanium-silicon alloys is investigated as a function of carrier concentration. It is shown that in a material with a finite grain size (typically 10−4 m to 10−8 m) the figure of merit is increased and that the optimum doping level is reduced over that which would be required in a single-crystal alloy.