Showing papers on "Doping published in 1968"
TL;DR: In this article, the authors measured the Hall coefficient of β-FeSi2 doped with cobalt (n-type) or aluminium (p-type), and found that the activation energy of the mobility is 0.06 eV, the density of states N = 1.2 × 1022 cm−3.
Abstract: Electrical conductivity, thermoelectric power and Hall coefficient of β-FeSi2 doped with cobalt (n-type) or aluminium (p-type) are measured between 100 and 1200 °K. The conductivity of n-FeSi2 follows an exponential dependence on temperature. The temperature dependence of the thermoelectric power cannot be interpreted on the basis of conduction in a band. With the assumption that conduction in n-FeSi2 is caused by small polarons, the mobility at room temperature is found to be μn = 0.26 cm2/Vs. The activation energy of the mobility is 0.06 eV, the density of states N = 1.2 × 1022 cm−3. The electrical properties of p-FeSi2 can be interpreted using the band model with a hole mobility μp ≈ 2 cm2/Vs, which varies as T−1/2 in the region of extrinsic conduction. From intrinsic conduction a band gap of 0.9 to 1.0 eV is deduced. The disappearance of the thermoelectric power at high temperature is related to the semiconductor-to-metal transition at 1200 °K.
225 citations
TL;DR: In this paper, a series of vanadium dioxide single crystals containing small concentrations of different impurity ions were grown by a thermal decomposition technique, and it was expected that these ions would produce a systematic change in the semiconductormetallic transition exhibited by the VO 2 phase.
143 citations
TL;DR: In this paper, the radiative processes in closely compensated GaAs doped with Si (p•type) and Si+Te (n−type) have been studied by photoluminescence between 300° and 77°K.
Abstract: The radiative processes in closely compensated GaAs doped with Si (p‐type) and Si+Te (n‐type) have been studied by photoluminescence between 300° and 77°K. These materials were grown by liquid‐phase epitaxy. The results strongly suggest that Si introduces two acceptor levels in GaAs with ionization energies of approximately 30 meV and ∼100 meV. In the n‐type material containing Si and Te only the radiative transition involving the deeper acceptor is observed (hvp∼1.44 eV at 77°K). In moderately Si‐doped, p‐type material (∼1018 cm−3 range), transitions involving both levels are observed. The apparent ionization energy of the deeper level moves to higher energies with increasing Si concentration while the shallow acceptor band appears to merge with the valence band. In the p‐type material, the electron transitions are assumed to originate at deep states (>40 meV) in the ``tail'' of states below the conduction band introduced by the high Si donor concentration. An intense broad emission band centered in the range 1.26 to 1.23 eV at 77°K is observed in some p‐type specimens. This band is attributed to an acceptor level 230±20 meV above the valence band. It is tentatively suggested that it involves an As vacancy or As vacancy complex.
126 citations
TL;DR: In this article, two special open-tube furnace systems, respectively containing all fused silica and all alumina furnace area components, and in which P is supplied through the reaction of wet H2 with AlP to form PH3, have been constructed for the growth of GaP crystals from Ga solution.
Abstract: Two special open‐tube furnace systems, respectively containing all fused silica and all alumina furnace‐area components, and in which P is supplied through the reaction of wet H2 with AlP to form PH3, have been constructed for the growth of GaP crystals from Ga solution. Careful attention has been paid to the purification of the PH3 and H2 transport gas. Unwanted contamination from the flow tubes and furnace area has been minimized. The crystals are then suitable for the controlled study of the optical properties of the impurities C and Si, persistent residual impurities in GaP crystals grown under less stringent conditions. The residual concentrations of S and N have also been dramatically reduced in this system. Clearly defined chemical evidence indicates that carbon rather than silicon is the shallow acceptor (ionization energy EA ∼48 meV) in the residual green donor‐acceptor pair luminescence spectrum in GaP. Analysis of sharp line donor‐acceptor pair transitions observed at the high‐energy tail of a broad red luminescence band (peak energy ∼1.96 eV) characteristic of silicon‐doped crystals indicates that silicon is a deep acceptor (EA∼204 meV) on P lattice sites and a shallow donor (ED∼80 meV) on Ga lattice sites in GaP. Sharp line green spectra observed for recombinations at C–Si and Zn–Si pairs confirm this value of (ED)Si. The shallow green pair transitions involving Si donors are strongly coupled to ∼17.5 meV and ∼29 meV low‐energy phonons, unlike pair recombinations involving P site donors. This marked difference in phonon coupling invalidates judgment of the relative values of ED for S, Te, and Si donors from the relative positions of the peak intensities of the green or red pair spectra involving these donors. Small shifts in the no‐phonon discrete pair lines between crystals doped with Si28 and Si30 confirm the suggested role of Si in these spectra.
111 citations
TL;DR: In this article, the authors studied the optical absorption, photoconductivity, contact photovoltage, electrical conductivity, and Hall coefficient of single crystals of WSe2 over the temperature range 77°-295°K.
Abstract: The optical absorption, photoconductivity, contact photovoltage, electrical conductivity, and Hall coefficient of single crystals of WSe2 have been studied over the temperature range 77°–295°K. It was found that the forbidden energy gap Eg was 1.35 eV at 295°K and that the temperature dependence of Eg was given by dEg/dT=−4.6×10−4 eV/°K. The material as grown by iodine vapor transport in a sealed ampule is p‐type with hole mobility μh∼80 cm2/V·sec and p∼1016/cc at 295°K. The carrier concentration could be reduced by pumping out excess selenium. Doping with rhenium during the crystal growth process resulted in n‐WSe2 with a carrier concentration n∼1017/cc and electron mobility μn∼100 cm2/V·sec at 295°K.
99 citations
TL;DR: In this paper, optical fluorescence and absorption associated with tellurium, an isoelectronic trap in CdS, are described and the temperature dependencies of the fluorescence decay times of both bands were measured and compared with various models for the recombination mechanisms.
Abstract: Optical fluorescence and absorption associated with tellurium, an isoelectronic trap in CdS, are described. At low temperatures two fluorescence bands can appear: one, with a peak near 6000 A, occurs in lightly doped crystals containing less than 1019 Te atoms/cm3; the other, with a peak near 7300 A, occurs in more heavily doped crystals. The temperature dependencies of the fluorescence decay times of both bands were measured and compared with various models for the recombination mechanisms. It is concluded that the 6000‐A band arises from bound hole‐electron recombination at isolated tellurium atoms on sulfur sites, while the 7300‐A band is probably associated with recombination at pairs of tellurium atoms on nearest neighbor sulfur sites. At room temperature, the quantum efficiency for electron‐beam excited fluorescence of of 7300‐A band can be near unity. The reasons for the high efficiency are discussed.
78 citations
IBM1
TL;DR: In this article, the electronic energy levels of a semiconductor depend on the state of strain of the semiconductor crystal and if some of the levels are occupied, the electronic contribution to the free energy of the crystal depends on the states of strain.
Abstract: Publisher Summary The electronic energy levels of a semiconductor depend on the state of strain of the semiconductor crystal. If some of the levels are occupied, the electronic contribution to the free energy of the crystal depends on the state of strain. The electronic contribution to the dependence of the energy on strain can be significant in moderately and heavily doped semiconductors and gives rise to easily observable dependences of elastic properties on doping. This chapter describes the electronic contribution to the elastic properties of certain types of semiconductors. Electronic energy is responsible for the binding and the elastic properties of many solids. Electronic models have frequently been used in calculations of the elastic constants of metal. The characteristic feature of this chapter is the use of semiconductor models that are useful in describing many other properties of semiconductors and whose parameters can be determined in a variety of ways. The study of electronic effects in the elastic properties of semiconductors has value for a number of reasons that are worth describing. Firstly, semiconductors are extremely important technologically. It is important to know their elastic properties in order that they may be properly used. Changes in moduli, thermal expansion, or magnetostriction with doping may have significant practical impact.
74 citations
TL;DR: In this article, approximate CV curves are calculated for a number of typical doping profiles near a semiconductor p-n junction, and these calculated curves can be used for the evaluation of doping profiles from experimentally determined C-V curves.
Abstract: Approximate CV curves are calculated for a number of typical doping profiles near a semiconductor p — n junction. These calculated curves can be used for the evaluation of doping profiles from experimentally determined CV curves. This evaluation of doping profiles from measured CV curves alone is never unambiguous. It is shown that it is often possible to reach a decision regarding the real profile, if additional information concerning the semiconductor material and the process of preparation of the junction is available.
62 citations
TL;DR: In this article, a study was made of n-type GaAs prepared by liquid phase epitaxy doped with Si, Ge, Sn, Te, and Se by photoluminescence and Te-doped material by transmission-electron microscopy.
Abstract: A study was made of n‐type GaAs prepared by liquid‐phase epitaxy doped with Si, Ge, Sn, Te, and Se by photoluminescence and Te‐doped material by transmission‐electron microscopy. A broad emission band centered at 1.2 eV (band B) is observed in LPE materials doped with group VI elements. Band B increases in intensity relative to the bandgap radiation with increasing dopant concentration in the 1018 cm−3 range. It is suggested that the recombination centers responsible for band B are the neutral (VGa+3 Te) complexes postulated by Vieland and Kudman, and that these represent the solid solution of Ga2Te3 in GaAs. With increasing dopant content, the solubility limit is eventually exceeded, and precipitates of this compound are then formed. These have been observed and identified by transmission‐electron microscopy. The radiative efficiency falls off sharply with increasing dopant content beyond 2–3×1018 cm−3 in materials doped with Se and Te. It is suggested that this fall off is partly due to nonradiative rec...
53 citations
Patent•
15 Mar 1968
TL;DR: In this article, the authors propose a method of decomposing a component of the DOPANT MATERIAL and placing it on the surface of the SEMICONDUCTOR.
Abstract: THIS INVENTION PROVIDES A METHOD OF DOPING SEMICONDUCTOR MATERIAL BY DECOMPOSING A COMPOUND OF THE DOPANT MATERIAL AND DEPOSITING THE ELEMENTAL DOPANT MATERIAL UPON THE SEMICONDUCTOR SURFACE.
45 citations
TL;DR: In this article, the photoelectronic properties of mercury sulphide crystals grown in an argon atmosphere by a slow convection technique were investigated. But the authors focused on the techniques of space charge conduction and quenching of photoconductivity which have been used to determine the location of localized levels in the energy gap.
TL;DR: Scharowsky's original method of growing ZnO-whiskers by blowing Zn and O2-vapor into a hot furnace has been scaled up and developed into a suitable process for producing single crystals of zinc oxide.
TL;DR: In this paper, it was shown by diffraction contrast experiments that the stacking-fault defects are extrinsic, i.e., rafts of tellurium substituting for arsenic in {111} planes.
Abstract: Samples of bulk-grown gallium arsenide single crystals, taken from both static freeze, and Czochralski ingots doped to a high level with tellurium, have been examined using transmission electron microscopy. Observation of single and multiple stacking-fault layers which have fault vectors of the kindR=a/3〈111〉 is reported. It is shown by diffraction contrast experiments that the stacking-fault defects are extrinsic. They are thought to be rafts of tellurium substituting for arsenic in {111} planes. The prevalence of the observed layer defects correlates well with the increase in carrier concentration in certain regions of the crystals.
TL;DR: In this article, the authors measured the piezoresistance and static magnetic susceptibility on phosphorus doped silicon with the donor concentration ranging from 6.10 18 cm -3 to 1.5·10 20 cm −3 and without compensation.
Abstract: Piezoresistance and static magnetic susceptibility are measured on phosphorus doped silicon with the donor concentration ranging from 6.10 18 cm -3 to 1.5·10 20 cm -3 and without compensation. Measurements are done over the temperature range from 1.5°K to 500°K The piezoresistance is in excellent accord with a picture that the donor electrons are in a rigid band with the same mass parameters as the conduction band of pure silicon, while the magnetic susceptibility shows deviation from this picture in two respects: one is the additional Curie type paramagnetism predominant at the lowest temperatures and the other is the large Pauli paramagnetism consistent only with larger and concentration dependent effective mass. A discussion is given of the source of these anomalies.
TL;DR: In this article, thermal conversion in quenched GaAs is caused both by copper acceptors and by shallow acceptors which are responsible for the 1.49 eV emission band in the original GaAs.
Abstract: GaAs crystals grown from the melt in silica boats without intentionally doping exhibit n‐type conductivity. Photoluminescence measurements at 20°K are used here to study thermal conversion in these crystals. Heat treatments with temperature TH ranging from 600° to 1100°C followed by quenching were performed on three crystals with different carrier concentrations. For TH≥900°C, it is concluded that the thermal conversion in quenched crystals is caused both by copper acceptors and by the shallow acceptors which are responsible for the 1.49 eV emission band in the original crystals. The latter acceptors are suggested to be silicon. It is proposed that conversion associated with silicon results from transfer of silicon atoms from donor sites to acceptor sites through a trapping process during rapid quenching. The maximum compensation due to these shallow acceptors is estimated, depending on the crystal used, to be on the order of 5×1016 cm−3 at 1100°C and is smaller at lower temperatures. For TH≤870°C, it app...
TL;DR: In this article, a deep penetration of aluminum ion in silicon was observed, extending to 0.58 µ. This penetration was depressed by removing the bombarded surface layer about 800 A in thickness before annealing.
Abstract: Radiation damages created in silicon single crystals bombarded with 10‐keV aluminum ions were examined by means of electron diffraction method. A deep penetration of aluminum ion in silicon was observed, extending to 0.58 μ. This penetration was depressed by removing the bombarded surface layer about 800 A in thickness before annealing. From these results, we interpret the deep penetration as a radiation enhanced diffusion effect.
TL;DR: In this article, the effect of ion implantation doping on the electrical characteristics of zinc-implanted GaAs diodes has been observed for the case of 70kV implantation at 400°C into substrates with n −type concentrations ranging from 1 × 10^16 to 1.8 × 10−18 atoms/cm^3.
Abstract: It has been found that ion implantation doping results in the generation and diffusion of defect species, forming deep trapping levels. The effect of these levels on the electrical characteristics of zinc‐implanted GaAs diodes has been observed for the case of 70‐kV implantation at 400°C into substrates with n‐type concentrations ranging from 1 × 10^16 to 1.8 × 10^18 atoms/cm^3. Capacitance‐voltage measurements have indicated the presence of a semi‐insulating layer in the diodes, varying in thickness from 0.18 μ for the most heavily doped substrate to 2.7 μ for the lightest. Frequency dependence of the junction capacitance and power law variation of forward current vs voltage have also been observed and are attributed to deep levels.
TL;DR: The forward and reverse I-V characteristics of diffused diodes made in silicon grown epitaxially on sapphire have been measured as mentioned in this paper, and the forward conduction current of all the diffused Diodes tested varied as exp ( qv /> nkT ) with n ≈ 1.7.
Abstract: The forward and reverse I–V characteristics of diffused diodes made in silicon grown epitaxially on sapphire have been measured. Silicon of doping density 4 × 10 15 to 6 × 10 17 /cm 3 p -type and 2 × 10 15 to 10 18 /cm 3 n -type have been used in these experiments. The forward conduction current of all diodes tested varied as exp ( qv /> nkT ) with n ≈ 1.7. Minority carrier lifetimes of the order 10 −10 sec have been inferred from the I–V data. The reverse currents were somewhat larger than predicted on the basis of currents generated in the space charge region but were reproducible from diode to diode. The temperature dependence of the diode currents was measured from room temperature to 200°C and followed the theoretical prediction. The variation of minority carrier lifetime with film thickness was measured, and the lifetime was found to increase as the silicon became thicker. Diodes produced by diffusion through the silicon to the silicon-sapphire interface were found to have minority carrier lifetimes about an order of magnitude lower than diodes not diffused to the bottom interface.
TL;DR: In this article, electron scattering and recombination studies through cyclotron resonance in doped silicon are carried out between 1.5 and 4.2°K, and it is found that below 4°K the electron resonance linewidth for p-type silicon consists not only of scattering effect, but also of lifetime broadening.
Abstract: Electron scattering and recombination studies through cyclotron resonance in doped silicon are carried out between 1.5 and 4.2°K. It is found that below 4.2°K the electron resonance linewidth for p -type silicon consists not only of scattering effect, but also of lifetime broadening. The latter can largely be eliminated on application of a strong uniaxial stress. So long as the scattering part is concerned, the observed features both for n -and for p -type materials are qualitatively explicable through the model of electron or positron scattering by a free hydrogen atom. Some discrepancies owing to the failure of the effective mass approach, however, are observed for all the dopants except for lithium. Analyses of temperature, stress and concentration dependence of electron lifetime in boron-doped silicon lead to the conclusion that the neutral boron impurities themselves are responsible for the carrier recombination.
TL;DR: In this article, experiments on introduction of boron acceptors and sodium donors were performed using P33 carbon black samples heat treated to various temperatures mainly in the range 1600-2400°C.
TL;DR: In this paper, the valence state of the dopant ions before and after heat treatment has been investigated using room temperature optical absorption measurements and both the growth problems and color change during subsequent heat treatment have been evaluated in terms of the ionic species which are present and the ease with which they are substituted into the alumina lattice.
TL;DR: In this article, absorption measurements were made before and after low-temperature electron irradiations of silicon samples which contained either dispersed oxygen, carbon, or carbon plus oxygen, and two distinctly different centers were formed upon lowtemperature irradiation depending upon the carbon and oxygen content.
Abstract: Infrared absorption measurements were made before and after low‐temperature electron irradiations of silicon samples which contained either dispersed oxygen, carbon, or carbon plus oxygen. Two distinctly different centers are formed upon low‐temperature irradiation depending upon the carbon and oxygen content. One center is the well‐known vacancy‐oxygen A‐center defect (836 cm−1) and is formed in oxygen‐containing silicon with a magnitude which is independent of the carbon content. The other center (922 and 932 cm−1) is formed only in silicon crystals which contain both oxygen and carbon. The results indicate that this center is formed by the trapping of a silicon interstitial at a carbon‐oxygen complex.
TL;DR: In this article, the authors measured drift mobilities and lifetimes in oriented single crystals of high resistivity, Li-doped ZnO by determining the transit time across a plane-parallel specimen for electrons which had been photoinjected at one surface by light pulses of about 10 sec duration.
TL;DR: In this article, the electrical properties of beryllium doped silicon were studied with IR absorption spectroscopy and electrical measurements, describing Be thermal diffusion, and they showed that the thermal diffusion can be described as a thermal diffusion process.
TL;DR: In this paper, a qualitative study of the masking properties of thin (≤1500Aa) silicon nitride and silicon oxynitride films on Si is presented.
Abstract: A qualitative study of the masking properties of thin (≤1500Aa) silicon nitride and silicon oxynitride films on Si is presented. A range of diffusion conditions was studied for doping sources including B, P, Ga, and As. Silicon nitride was not found to be a diffusion mask for all conditions. Conditions under which it can be expected to mask are specified.
TL;DR: In this paper, the electrical and optical properties of silicon-on-sapphire films have been measured as a function of both film thickness and doping density, and the Hall mobility is shown to increase as the film thickness increases and as the doping density decreases.
TL;DR: In this paper, the thermal conductivity of amorphous semiconducting system Se-Ge in the temperature range of 100 to 300°K was measured and the Debye model was used for the analysis of the experimental values and the calculated mean free path of phonons was related to the size of the basic structure units of the selenium glass.
Abstract: The thermal conductivity of the amorphous semiconducting system Se-Ge in the temperature range of 100 to 300°K was measured. The Debye model was used for the analysis of the experimental values and the calculated mean free path of phonons was related to the size of the basic structure units of the selenium glass. The shift of the thermal conductivity of amorphous selenium doped with germanium was explained by means of the increase of the velocity of sound observed together with the occurrence of the covalent bond Se-Ge between the basic structure units of the studied amorphous system.