Showing papers on "Doping published in 1975"

The electrical properties of polycrystalline silicon films

Abstract: Boron doses of 1×1012–5×1015/cm2 were implanted at 60 keV into 1‐μm‐thick polysilicon films. After annealing at 1100 °C for 30 min, Hall and resistivity measurements were made over a temperature range −50–250 °C. It was found that as a function of doping concentration, the Hall mobility showed a minimum at about 2×1018/cm3 doping. The electrical activation energy was found to be about half the energy gap value of single‐crystalline silicon for lightly doped samples and decreased to less than 0.025 eV at a doping of 1×1019/cm3. The carrier concentration was very small at doping levels below 5×1017/cm3 and increased rapidly as the doping concentration was increased. At 1×1019/cm3 doping, the carrier concentration was about 90% of the doping concentration. A grain‐boundary model including the trapping states was proposed. Carrier concentration and mobility as a function of doping concentration and the mobility and resistivity as a function of temperature were calculated from the model. The theoretical and ex...

Impurity profiles of GaAs epitaxial layers doped with Sn, Si, and Ge grown with molecular beam epitaxy

Abstract: Molecular beam epitaxy (MBE) n−type GaAs layers are commonly doped with Sn, Si, and Ge. The abrupt doping profiles resulting from these three dopants differed significantly when the epitaxy was carried out between temperatures ranging from 550 to 615 °C. The abrupt doped profile of Sn−doped GaAs layers when grown above 550 °C did not follow the time−intensity profile of the dopant beam, while layers doped with Si or Ge did. In the case of Sn, the effect is attributed to surface segregation during deposition.

Te and Ge — doping studies in Ga1−xAlxAs

Abstract: The temperature dependence in the range 77–400 K of the carrier concentration, resistivity and mobility of a series of n and p-type single crystal, liquid-phase epitaxial layers of Ga1−xAlxAs are presented. These layers were doped, n-type with tellurium, and p-type with germanium to yield carrier concentrations in the range 1017 – 1018cm−3 at 295 K. Donor and acceptor ionization energies, eD and eA, are derived from the data. The dependence of eD on alloy composition is interpreted in terms of the known band structure variation in the alloy system.

Comparison of interface-state generation by 25-keV electron beam irradiation in p-type and n-type MOS capacitors

Abstract: The interface state induced by 25‐keV electron beam irradiation in MOS capacitors having p‐ and n‐type substrates with several different doping concentrations have been studied. For radiation dosage on or above the order of 1×10−5 C/cm2, all of the radiation‐induced interface‐state distributions tend to have a similar shape which is asymmetrical about the midgap, independent of the type and concentration of the silicon dopants, and independent of the initial interface‐state distributions. The states in the upper half of the silicon band gap are acceptor type which peak around 0.2 eV from the midgap, whereas the states in the lower half of the band gap are donor type with a lower density. For radiation dosage below 1×10−7 C/cm2 the postradiation interface states are proportional to their initial values. An explanation based on the broken bond model is presented to account for the observations.

Luminescence in highly conductive n‐type ZnSe

Abstract: We have studied the photoluminescence of ZnSe doped by diffusion of Al at high temperature (1000–1100 °C) or by Ga at low temperature (600 °C). The diffused samples are highly conductive (0.1<ρ<10 Ω cm). According to the doping conditions the luminescence, at 300 °K, is dominated by the well‐known self‐activated orange emission (6300 A) or by a yellow‐green band that we assign to Na‐Al complexes. Annealing in zinc atmosphere was found to have a large influence on the photoluminescence of the Ga‐doped samples only. Thus, at 300 °K, the annealed samples exhibit a blue intrinsic emission with a strong reduction of the orange or the yellow‐green bands; at 77 and 4.2 °K the photoluminescence spectra are dominated by blue lines corresponding, respectively, to free‐electron–acceptor or donor‐acceptor recombinations. We show that the shallow acceptor involved is Na.

Stimulated emission from Er3+ ions in yttrium aluminum garnet crystals at λ = 2.94 μ

Abstract: Stimulated emission due to the 4I11/2–4I13/2 transition (λ = 2.936 μ) in yttrium aluminum garnet (Y3Al5O12) doped with Er3+ ions (30 wt%) was observed for the first time at 300°K. The output energy from crystals of 50×3 mm dimensions was 0.3 J under free-oscillation conditions and 0.05 J in the case of Q switching. The lifetime of the 4I11/2 level was determined for crystals with 3–30 wt% Er3+. The energy from the higher Er3+ levels relaxed in a cascade manner through 4I11/2 to 4I13/2.

p‐n junction zinc sulfo‐selenide and zinc selenide light‐emitting diodes

Abstract: The wide‐band‐gap group II–group VI compound semiconductors have long been valued for their luminous efficiency, and an obvious application would be p‐n junction LED’s. However, these materials could only be made n type, not p type. Using an uncustomary technique, we have succeeded in making stable low‐resistivity p‐type ZnSxSe1−x and ZnSe by diffusion into n‐type substrates, and thereby have made low‐resistance LED’s. The diffusion process is carried out in two steps: a deposition step followed by a drive‐in. Gallium, indium, and thallium are used to make the material p type. (i) The group IIIA element is present in doping quantities only. (ii) p‐type mobility values are presented as a function of hole concentration; temperature dependence establishes that the level is shallow. (iii) The LED’s have low resistance and the light output is linear with current above the barrier voltage. (iv) Generation current from the junction, n=2, is observed below the barrier voltage. External quantum efficiencies around...

Energy Levels of Electron and Hole Traps in the Band Gap of Doped Anthracene Crystals

Abstract: It is discussed under which conditions electron and hole trap levels in the band gap of doped molecular crystals may be described by a simple polarization model taking into account the shift of electron and hole levels (positive and negative ionic states) of the free dopant molecule during its incorporation into a polarizable crystal-continuum. Measurements are presented for anthracene doped with tetracene (T), acridine (Ac), and phenazine (Ph). The trap levels obtained are: E = 0.42 eV; E = 0.12 to 0.17 eV (depending on the orientation); E = 0 eV; E = 0.21 eV, E = 0 eV; E = 0.54 eV for holes (p) and electrons (n), respectively.

Semi-insulating properties of Fe-doped InP

Abstract: Semi-insulating InP having a room-temperature resistivity of greater than 107 Ωcm was prepared by Fe doping. The current/voltage characteristic of the material changed from ohmic to V2 dependent at about 104 V/cm. Temperature dependence of the resistivity gave an activation energy of 0.66 eV. The Hall effect was negative, and the observed electron concentration was about 109 cm−3.

Raman Spectral Characterization of Pure and Doped Fused Silica Optical Fibers

Abstract: The utility of Raman spectroscopy as a means of characterizing the properties of pure and doped fused silica has been investigated. Laser-Raman spectra were obtained by forward scattering from solid optical fibers ~35 to 85 m in length using 514.5 nm excitation with an "image slicer" and a Cary model 81 instrument. Clad and unclad fibers of fused silica and doped fibers having SiO2-GeO2 and SiO2-GeO2-B2O2 cores were examined. Raman spectra were also obtained from bulk samples of glasses, including pure GeO2, pure B2O3, and various compositions of SiO2-GeO2, SiO2-B2O3, and SiO2-GeO2-B2O3. The addition of dopants to fused silica was found to alter the Raman spectrum both by the appearance of new bands, roughly proportional to dopant concentration and not common either to the fused silica or to the dopant alone, and by the marked alteration of other Raman bands, which is indicative of changes in the local intermolecular order. Thus, addition of GeO2 produces new Raman bands at ~675 and ~1000 cm−1; and of B2O3, new bands at ~940 and ~1350 cm−1. Addition of GeO2 and/or B2O3 weakens the relatively sharp Raman lines near 485 and 600 cm−1 (and a similar but small effect was also noted with increasing OH content). GeO2 and B2O3 together also produce observable narrowing of the broad intense 440 cm−1 Raman contour. These spectral effects are interpreted, respectively, in terms of a decrease in the concentrations of [Equation] and [Equation] defects produced by dopant addition and of a concomitant reordering of the silica structure. Raman spectroscopy thus appears to be a useful optical technique for elucidating the properties of dopants that have been especially chosen for good optical transmission and hence are not easily detectable by absorption measurements.

Determination of the semiconductor doping profile right up to its surface using the MIS capacitor

Abstract: A new method has been developed by which the doping profile of the semiconductor can be obtained right up to its surface. Contrary to the well known dC/dV-method, which is valid only in the depletion range, we have considered the majority carriers in deriving relations for doping density as well as distance from the semiconductor surface, in terms of the space charge capacitance and its derivative with respect to the surface potential. This method can be realized experimentally on any MIS structure. Measurements on MOS capacitors with steam grown oxides showed a drooping profile towards the SiSiO2 interface for boron doped and a rising one for phosphorus doped silicon. Post-oxidation annealing in dry nitrogen at 1200°C produced a uniform profile for phosphorus doped silicon.

Dependence of resistivity on the doping level of polycrystalline silicon

Abstract: The electrical resistivity of polycrystalline silicon films has been studied as a function of doping concentration and heat treatment. The films were grown by the chemical vapor decomposition of silane on oxidized silicon wafers. The resistivity of the as−deposited films was widely scattered but independent of dopant atom concentration at the lightly doped levels and was strong function of dopant level in the more heavily doped regions. Postdeposition heat treatments in an oxidizing atmosphere remove scatter in the data. The resultant resistivity for dopant levels less than 1016 atoms/cm3 was approximately equal to that of intrinsic silicon. In the next 2 orders of magnitude increase in dopant level, the resistivity dropped 6 orders of magnitude. A model, based on high dopant atom segregation in the grain boundaries, is proposed to explain the results.

Experiments on the Origin of Process Induced Recombination Centers in Silicon.

Abstract: Densities of recombination centers obtained by the transient capacitance technique in diffused p+n junctions and Al−nSi Schottky barriers are correlated with process variables of more than 70 diffusion and heat−treatment experiments. Results show that the two process−induced donor defect centers reported previously are generated at the strained and disordered silicon surface layers either from high−surface concentration phosphorus or boron diffusion or from mechanical lapping. Chemically polished surfaces appear to act neither as a source nor a sink of these defect centers. The defects are not related to oxygen in the original silicon nor oxygen introduced during oxidation or diffusion. The effects of phosphorus and boron surface concentrations, phosphosilicate surface glass layers, and diffusion temperatures on the concentrations of these two centers are investigated. Nearly constant defect concentration profiles at depth more than 50 μ from the surfaces are observed, suggesting an L−shaped defect concne...

Limitations of the CV technique for ion-implanted profiles

Abstract: The CV profiling technique is reviewed and its validity and limitations are investigated, with special attention given to the case where the method is extended to the study of ion-implanted impurity distributions. A theoretical analysis is described which yields information about the dependence of CV measurements on impurity profile. The inverse problem is then considered and the results demonstrate that the depletion approximation formulas commonly used for the reduction of CV data to give doping profiles are misleading when applied to substrates with rapidly varying profiles as are generally the case for ion-implanted substrates. Examples of the profiles obtained for various shaped impurity distributions are given.

Frequency dependence of the photo-EMF of strongly inverted Ge and Si MIS structures—I. Theory

Abstract: The dependence of the real and imaginary photo-EMF components on frequency of the incident light modulation has been calculated for Ge and Si MIS structure in the inversion regime at the interface. It is shown that physical parameters of a semiconductor, such as doping levels in the bulk and near the interface, the rate of surface recombination proceeding at the backside of the sample, diffusion coefficient of minority carriers and light absorption coefficient can be derived from the experimental results.

Triplet exciton percolation and superexchange: Naphthalene C10H8–C10D8

Abstract: The phosphorescence of betamethylnaphthalene doped into a naphthalene−h 8/naphthalene−d 8 mixed crystal has been measured. The results demonstrate that (1) dynamical excitonpercolation does occur (i.e., a transition from an excitoninsulator to an exciton conductor), that (2) it is very useful for the investigation of energy transfer in molecular aggregates, and that (3) it is a critical test of our current knowledge of exciton exchange and superexchange. (AIP)

Growth and characterization of liquid−phase epitaxial InxGa1−xAs

Abstract: The liquid−phase epitaxial growth of InxGa1−xAs (0

Semiconductor Measurement Technology

Abstract: : ;Contents: Resistivity; dopant profiles; Crystal defects and contaminants; Oxide film characterization; Test patterns; Photolithography; Epitaxial layer thickness; Wafer inspection and test; Interconnection bonding; Hermeticity; Thermal properties of devices.

Free-to-bound transition in β-SiC doped with boron

Abstract: There are two series of infrared emission bands in β-SiC doped with boron. One of them is predominant at lower temperatures, and has already been assigned to be due to the nitrogen donor–boron acceptor pair recombination. The other one, designated as A emission, is investigated in detail. It is shown that both the spectral shape of the zerophonon band of the A emission and its temperature dependence are well described by the free-to-bound transition model. The recombination of electrons in the conduction band with holes trapped at the boron acceptors will be responsible for the mechanism of the A emission. The ionization energies of the nitrogen donor and the boron acceptor are estimated to be about 0.055 and 0.735 eV, respectively. Es gibt zwei Typen von ultraroten Emissionsbanden in Bor-dotiertem β-SiC. Eine dieser Emissionsbanden herrscht bei niedrigeren Temperaturen vor und wurde bereits der Stickstoff-Donator–Bor-Akzeptor-Paarrekombination zugeordnet. Die andere Emissionsbande, die A-Emission genannt wird, wird ausfuhrlich untersucht. Es wird gezeigt, das sowohl die spektrale Form der Null-Phononbande als auch deren Temperaturabhangigkeit mit dem Modell von Ubergangen zwischen freien und gebundenen Zustanden erklart werden kann. Rekombination von Leitungselektronen mit Lochern in den Akzeptorzustanden ist fur den Mechanismus der A-Emission verantwortlich. Die Aktivierungsenergien des Stickstoff-Donators und Bor-Akzeptors werden auf 0,055, beziehungsweise 0,735 eV geschatzt.

An optical study of defects in silicon irradiated with fast neutrons

Abstract: Crystals of silicon which were pure, and either monocrystalline or polycrystalline, or were doped with oxygen, or with carbon and oxygen have been irradiated at room temperature with fast neutrons to doses in the range 1015-1020 n0 cm-2. After irradiation, measurements were made of the strengths of the induced electronic absorption due to divacancies at 1.7 mu m and that due to band tailing below fundamental edge ( lambda =1.05 mu m) together with the vibrational one-phonon absorption below the Raman frequency omega R (band mode) and intrinsic local-mode features just above omega R. These features were independent of the degree of crystal perfection and the presence of impurities. Annealing studies showed a major stage near 150 degrees C when all the divacancies were lost; the anneal temperature decreased systematically with increasing n degrees dose and was reduced further in the polycrystalline samples, but was unaffected by the impurities.

Cadmium Telluride Nuclear Radiation Detectors

Abstract: The characteristics and performance of undoped high resistivity cadmium telluride detectors are compared to chlorine compensated counters. It is shown, in particular, that "undoped" CdTe Is in fact aluminium doped and that compensation occurs, as in silicon or germanium, by pair and triplet formation between the group III donor and the doubly charged cadmium vacancy (Vcd) acceptor. Furthermore, in chlorine doped samples, the polarization effect results from the unpaired (Vcd) level at Ec -0. 6 eV.

Method of producing a doped zone of one conductivity type in a semiconductor body utilizing an ion-implanted polycrystalline dopant source

Abstract: A semiconductor body is coated at selected areas thereof with a polycrystalline or amorphous semiconductor layer, a dopant is ion-implanted into such polycrystalline or amorphous layer and the resultant structure is then subjected to diffusion conditions to diffuse the dopant from the polycrystalline or amorphous layer into the select zone of the semiconductor body. This process causes very slight disturbances in the crystal lattice of the semiconductor body and provides an adjustable dopant concentration at select surface zones of the semiconductor body.

Semiconductor component with dielectric carrier and its manufacture

Abstract: A semiconductor component of a semiconductor or circuit system is provided. The circuit incorporates a dielectric carrier comprised of synthetic material. The circuit is provided with plate-shaped semiconductor islands. The islands possess doping layers and are interconnected as desired with a thin film wiring. A process for the production of such product is also provided.