Showing papers on "Doping published in 1973"

Transport equations in heavy doped silicon

Abstract: The general transport equations in a heavy doped semiconductor are given, taking the position-dependent band structure into account. An intrinsic concentration depending on the doping levels is introduced. This quantity allows us to use the classical equations in a slightly modified form, if Maxwell-Boltzmann statistics can be applied for one or both kinds of the carrier. The total density of states in a heavy doped semiconductor is assumed to be the envelope of the density of states of the conduction (valence) band and impurity band. The effect of the skewness of the impurity band is included. The Fermi level and the effective intrinsic carrier concentration are calculated for this total density of states function. Experimental evidence for the calculated values is given.

Violet luminescence of Mg‐doped GaN

Abstract: The photoluminescent and electroluminescent properties of GaN–GaN:Mg diodes are described. Visible violet electroluminescence was observed with excitation voltages of 10–20 V with the emission peak in the region of 2.9 eV. The I‐V characteristics showed I ∞ V3 in the region where light was emitted, and the observed power efficiency was approximately 10−5. A photoluminescence peak at 2.9 eV provided additional evidence for an acceptor level, associated with the Mg impurity, about 0.5 eV above the valence band.

Luminescence of Be‐ and Mg‐doped GaN

Abstract: The luminescence of vapor‐grown GaN doped with Be or Mg shows deep emission bands in the yellow‐green (Be) or blue‐violet (Mg) wavelength regions in addition to the near‐gap features previously recognized in Zn‐ and Cd‐doped GaN. The crystals are of high resistivity at high Be or Mg doping levels.

Influence of AsH3, PH 3,and B 2 H 6 on the Growth Rate and Resistivity of Polycrystalline Silicon Films Deposited from a SiH4 ‐ H 2 Mixture

Abstract: The deposition rate of polycrystalline silicon from a mixture is significantly influenced by the addition of , ,and . At a deposition temperature of 680 °C causes a decrease by a factor of 7, causes a decrease by a factor of 2.5, while a two times higher deposition rate is obtained with addition. Out of these three dopant hydrides and do not affect the activation energy of the deposition reaction compared to undoped growth (37 kcal/mole). The Arrhenius plot for the deposition of silicon from a mixture shows two activation energies: 20 kcal/mole at and 7 kcal/mole below 620°C. The experimentally found minimum values of the resistivity of doped polycrystalline silicon can be explained in terms of solid solubility and carrier mobility. At deposition temperatures below 700 °C with and without addition of dopants the polycrystalline silicon surface is mirror‐like. Significant differences have, however, been observed by electron microscopy. Compared to undoped growth boron was found to lower the etch rate of the polycrystalline silicon film markedly.

Effect of Pb- and Te-saturation on carrier concentrations in impurity-doped PbTe

Abstract: Ingots of PbTe have been grown by the Bridgman method from melts doped at a level of approximately 1 × 1020 cm−3 with one of the following impurities: Cu, Ag, In, Tl, As, Sb, and Bi. Hall coefficient measurements have been made at 300 and 77K to determine the carrier type and concentration in as-grown, Pb-saturated, and Te-saturated single-crystal samples cut from these ingots. Both Ag and As are amphoteric dopants: Ag is a donor in Pb-saturated samples and an acceptor in Te-saturated ones, while As exhibits the opposite behavior. Only As- and Tl-doped samples are p-type after Pb-saturation. All samples are p-type after Te-saturation at 800° C, but those doped with In, As, Sb, and Bi are n-type after Te-saturation at 350° C. In some cases the Hall coefficient changes between 300 and 77K in a manner that is unusual for PbTe. It decreases by more than a factor of 3 for some n-type, In-doped samples and increases by more than 2 orders of magnitude for some p-type, Cu-doped samples that have been Te-saturated at 800° C.

Gallium nitride metal-semiconductor junction light emitting diode

Abstract: A light emitting diode comprising a first layer of gallium nitride, a second, substantially intrinsic layer of magnesium doped gallium nitride forming a junction therewith, a metallic rectifying contact to the second layer, an ohmic contact to the first layer, and means for applying a voltage across said contacts and said junctions whereby to bias the device and generate light.

Ionized impurity scattering in degenerate In 2 O 3

Abstract: Thin films of In2O3 are prepared by the spraying method. The concentration of charge carriers is changed from about 8×1019 cm−3 to 5×1020 cm−3 by suitable doping with Sn. The optical effective mass is found to depend slightly on carrier concentration. Electrical and optical measurements indicate that electrons are scattered predominantly by charged impurity centres. Structural investigations show that grain boundary scattering can be neglected. The interpretation of the experimental results is mainly based on a paper by von Baltz and Escher, where analytical formulas for the imaginary part of the complex dielectric constant are given for the most important scattering mechanisms in (degenerate) semiconductors.

Electrical properties of CuInSe2 single crystals

Abstract: Various bulk electrical properties and device characteristics have been measured. It has been shown that the majority carrier type is dependent on crystal stoichiometry. Mobilities of 660 cm2/V sec and 30 cm2/V sec have been measured for n-and p-type samples, respectively. Rectifying contacts and p-n junctions have been investigated by small signal analysis and the associated doping levels and equilibrium band diagrams have been determined. Photovoltage measurements on rectifying contacts have shown that the band-gap has a value of 0.95 ± 0.01eV.

Stabilized semiconductor devices and method of making same

Abstract: Instabilities in the leakage current and threshold voltage of a field-effect transistor (FET) on an insulator, at both room temperature and after operation at relatively high temperatures (150 DEG C), are substantially reduced by selectively doping edge regions adjacent to the transverse side surfaces of the channel region of the FET. The selective doping comprises implanting atoms into these edge regions, as by ion implantation or diffusion, to provide therein a carrier concentration of at least 5x1016cm 3 atoms of the opposite conductivity type to that of the source and drain regions of the FET.

Properties of Epitaxial Gallium Arsenide from Trimethylgallium and Arsine

Abstract: Electrical and optical properties of epitaxial layers grown from trimethylgallium and arsine were studied by Hall and photoluminescence measurements The conduction type of the layers grown on substrates was changed from p‐ to n‐type with increase of , the mole ratio of arsine to trimethylgallium introduced, without intentional doping An emission (P2) at 1488 eV due to shallow acceptors was observed on most of the samplesCorrelations between the carrier concentration and the intensity of the P2 emission with suggest that the main acceptor impurities in the epitaxial layer are amphoteric ones on As sites, such as carbon and silicon contained in the trimethylgallium source Results of the mass‐spectrographic analysis of the layers are consistent with the above suggestion

A new method of growing GaP crystals for light-emitting diodes

Abstract: A method named synthesis, solute diffusion (SSD) has been developed for growing compound semiconductor crystals, GaP in particular, for light-emitting diode (LED) use. The grown crystal is cylindrically shaped and is composed of fairly large-size grains. Growth rate is limited by the diffusion process of phosphorus in the gallium melt. The diffusion coefficient was obtained from the growth rate and found to be 8×10-5cm2s-1at 1100°C with an activation energy of 0.65 eV. Donor impurities, tellurium or sulfur, can be reproducibly incorporated from 3×1017to 4×1018cm-3, with segregation coefficients at 1150°C, 0.038 and 1.0, respectively. The quality of the grown crystals was observed to be exceptionally good, and the saucer-type pits were hardly observable in the crystal on modified AB etching. Highly efficient red-light-emitting junctions were reproducibly grown by only one single-layer-single-liquid-epitaxy process, in which zinc was doped from the vapor phase. A double-layer-single-epitaxy process, which we call "liquid epitaxial grown-in junction" process, was also developed and it produced highly efficient green LED's. The LED's grown on the SSD wafers have efficiencies up to 7.4 percent for red and 0.15 percent for green.

Thermochromism and Electrical Conductivity in Doped SrTi O 3

Abstract: Large reversible thermochromic changes in pure and transition-metal-doped SrTi${\mathrm{O}}_{3}$ were observed which depend markedly on impurity concentration, anealing temperature, and especially on the rapidity of the quench. The material also changes its electrical properties from insulator to semimetallic, and for moderately and heavily doped samples, from semiconductor to metalliclike behavior. The optical and electrical properties are stable. Two intrinsic optical-absorption bands and two bands previously found in photochromic studies which depend on the transition-metal impurity are observed. A partial energy-level scheme for SrTi${\mathrm{O}}_{3}$ is proposed.

On phosphorus diffusion in silicon under oxidizing atmospheres

Abstract: Phosphorus diffusion in silicon has been carried out in both inert (nitrogen) and oxidizing (90% nitrogen plus 10% oxygen, dry oxygen, steam) atmospheres, over a wide temperature range (1000–1200°C) and for doping concentrations usually encountered in the silicon planar technology. The experimental data, interpreted on the basis of the Kato and Nishi theoretical model taking into account the redistribution phenomena at the moving oxide-silicon interface, show that the phosphorous diffusion coefficient is strongly influenced by the nature of the ambient atmosphere in which the diffusion is carried out. Two different values for the activation energy of the diffusion process, Ei = 3·5 eV for the inert and E0 = 2·5 eV for the oxidizing conditions, have been found. These values seem to confirm the phosphorous diffusion mechanism based on E-centers for the inert case, while for the oxidizing case a different diffusion mechanism should be considered.

Metal-to-non-metal transitions in doped germanium and silicon

Abstract: The metal-to-non-metal (MNM) transitions in shallow donor states of Ge and Si are studied by means of Hubbard's tight-binding model. The donors are assumed to form a regular lattice, and the hopping integral and the intra-donor repulsion integrals are calculated from the wavefunctions of single isolated impurities. The calculated critical densities for the onset of the MNM-transitions compare well with empirical values and with Mott's criterion. The only input parameters to the calculations are the experimentally determined ionization energies, the effective masses in the conduction band, and the background dielectric constants. Estimates are also made for the concentration at which the impurity band merges into the conduction band.

Method of making an ohmic contact with a semiconductor substrate

Abstract: Disclosed is a method of producing a semiconductor device in which a p-n junction and an ohmic contact with the semiconductor substrate are simultaneously formed. A layer of a metal containing an impurity of one conductivity type is deposited on a surface of a semiconductor body of the opposite conductivity type. The metal layer is then subjected to heat treatment, thereby to cause the impurity to diffuse into the semiconductor body to form the p-n junction. At the same time, a compound is formed of the metal and the semiconductor which serves as an ohmic contact with the semiconductor body at the region in which the impurity is diffused.

Integrated circuit fabrication process

Abstract: Integrated circuits of high density are fabricated in a simplified process which allows both the use of multiple conducting layers in a dielectric above a semiconductor substrate, such as a polycrystalline silicon (polysilicon) field shield and metal interconnection lines, while also making provision for very precise alignment of subsequent layers to diffusions. A doped oxide containing a suitable dopant, such as arsenic in the case of a p-type silicon substrate, is deposited on the substrate. A pattern corresponding to desired diffusions is generated by normal photolithographic and etching techniques. A second, undoped oxide layer is thermally grown over the semiconductor substrate with dopant from the doped oxide simultaneously diffusing into areas of the substrate underlying the doped oxide. The undoped oxide serves to prevent autodoping. Thermally growing the undoped oxide layer converts a layer of the semiconductor surface not covered by doped oxide to the undoped oxide. Both oxide layers are then removed, leaving slight steps at the surface of the semiconductor substrate around the diffusion. The slight steps serve to allow very precise alignment of masks for subsequent process steps. Otherwise, the structure produced is very planar. An insulating layer, desirably a composite of silicon dioxide and silicon nitride in the case of a silicon substrate, is then formed on the substrate, followed by a layer of polycrystalline semiconductor, desirably doped to provide high conductivity. Openings are then etched in the polycrystalline semiconductor layer to allow formation of gate electrodes of FET''s, contact to the substrate, and contact of a subsequent interconnection metallization to diffusions in some of the circuits. A second insulating layer, such as silicon dioxide, is then grown on the polycrystalline semiconductor layer. Contact holes are then made to diffusions in the substrate, the substrate itself, and the polycrystalline silicon. The deposition and etching of an interconnection layer on the second insulating layer completes fabrication of the integrated circuit.

The Photoconductivity of Poly(N-vinylcarbazole). V. The Doping Effects of Various Materials on the Photoconductivity

Abstract: The photoconductivity and fluorescence spectra of poly(N-vinylcarbazole) (PVCz) films doped with various materials were investigated. The photoconductive properties of doped films may be grouped into three classes according to the kind of dopant. The doping of an electron donor, such as tetramethyl-p-phenylenediamine and 1,5-diaminonaphthalene, reduced the photocurrent in all the wavelength regions by a factor of 102 to 104 because of the hole-trapping effect of the dopant molecule. The exciplex formed between the donor and PVCz does not seem to contribute to the photocurrent. The doping of an acceptor, such as TCNE and dimethyl terephthalate, on the other hand, enhanced the photocurrent. The field-assisted thermal dissociation of an excited CT complex formed between PVCz and an acceptor seems to be a carrier generation process. The doping of anthracene or perylene quenched the fluorescence of PVCz by a factor of 10 to 30 and reduced the photocurrent in the UV region by a factor of 2 to 7, while it enhanc...

Diffusion in the III–V Compound Semiconductors

Abstract: Of the various compound semiconductors, the III–V compounds have properties most similar to the group IV elemental semiconductors. Like Si and Ge, the III–V compounds may readily be doped as n- orp-type to form p-n junctions, the most useful and widespread application of semiconductors. They are 1-to-l chemical compounds of the group III elements B, Al, Ga, and In with the group V elements N, P, As, and Sb. The III–V compounds are tetrahedrally coordinated, and the majority crystallize in the zinc-blende structure illustrated in figure 6.1 for GaAs. The zinc-blende structure is the diamond lattice of Si or Ge, but with group III and V atoms occupying adjacent lattice sites. Although the diamond and zinc-blende structures are similar, the differences in lattice constant, the presence or absence of d-shell electrons, and the ionicity of the III–V compounds result in significant differences in the band structure [1]. The varied band structures and large range of energy gaps possible with the III–V compounds have led to many potential applications. The crystal structure, lattice constant, type of energy gap, and the room temperature energy gap are summarized in Table 6.1 for the elemental semiconductors Si and Ge and the III–V compound semiconductors.

Measurement of carrier-concentration profiles in epitaxial indium phosphide

Abstract: A technique is described for measuring carrier-concentration profiles of vapour-deposited epitaxial indium phosphide using the capacitance/voltage characteristics of a reverse biased metal-insulator-semiconductor diode. Profiles of layers grown on chromium and tin-doped substrates are presented. The effect of dopant type on the sharpness of electrical interfaces is discussed.

Luminescence from In0.5Ga0.5P prepared by vapor‐phase epitaxy

Abstract: The photoluminescence from n‐ and p‐type In1−xGaxP with x≃0.5, prepared by vapor‐phase epitaxy on GaAs substrates, has been studied between 4.2 and 300 K. This material is of particular practical interest because of its close lattice‐parameter match with GaAs and direct energy band gap of 1.9 eV. At very low temperatures, four major emission bands have been identified, involving intrinsic recombination, donor—to—valence‐band transitions, conduction‐band—to—acceptor transitions, and donor‐acceptor transitions. The intrinsic recombination dominates in all the samples above about 150 K. The spectra are consistent with a shallow donor ionization energy of 7±1 meV, the same value as in InP. The spectral data of Cd‐doped samples (with p varying from 1.8×1016 to 9.3×1017 cm−3) suggest a consistent shift of the Cd acceptor ionization energy to lower values with increasing doping. The extrapolated value for very low doping is 59±2 meV at 50 K. The residual donor density is low in all the p‐type samples studied (≲ ...

Vapor‐Doped Multislice LPE for Efficient GaP Green LED's

Abstract: A single‐step liquid phase epitaxy process has been developed for the growth of efficient green light‐emitting diodes (LED's), in which all doping is accomplished from the vapor phase. The use of vapor‐phase doping increases the flexibility of the LPE process since junction formation and control of doping profiles is accomplished by regulating the composition and flow rates of the doping gases. This method has been applied to multislice growth on large area substrates (up to 38 mm in diameter). Thin melts and nearly complete utilization of the GaP initially dissolved in the melt minimize the gallium usage. Encapsulated LED's with efficiencies in the 0.10–0.15% range at 7 A/cm2 are obtained routinely. These efficiencies are comparable to the highest values reported to date for low current operation. Efficiencies as high as 0.2% have been obtained at 7 A/cm2 using this method. The short deposition time for this single‐step method, reproducibility, multislice capability, and minimum gallium consumption make this method economically attractive for the high level production of efficient green LED's.

Experimental verification of the Shockley--Read--Hall recombination theory in silicon

Abstract: The dependence of carrier lifetime on injection level has been measured in silicon power devices. As examples, the results of an Au-doped and an as-processed, not intentionally doped, specimen are given. The experimental results confirm the Shockley–Read–Hall recombination theory. The ratio of the capture cross-sections of the holes and electrons is calculated.

Effective recombination levels in n- and p-type silicon irradiated by 4·5 MeV electrons

Abstract: The effective recombination levels created at room temperature by 4·5 MeV electron irradiation are deduced from the variations in lifetime vs carrier injection rate, electron fluence, and temperature. This paper aims to compare the properties of the created recombination energy levels and defect centers in N- and P-type silicon single crystals. The characteristics of the samples used extend over a wide range of resistivities, doping impurities and crystal growth techniques. A pulsed neodymium laser has been employed to carry out these studies, and the carrier lifetime has been measured by the photoconductivity-decay method. Information on the specific centers is deduced from the comparison of the present macroscopic results on energy levels and annealing studies with the known properties of microscopic defects. From the results obtained, several types of recombination centers are simultaneously created in N- and P-type silicon, and crystal impurities other than oxygen and dopants may play a big part in the constitution of such centers. In the P-type silicon case, 3 types of recombination centers are clearly operative: (1) centers with a ∼Ev+0·20 eV energy level, which could be divacancies, and which would cease to act as recombination centers by trapping irradiation induced interstitial carbon atoms, (2) centers with a ∼Ev+0·24 eV level which may involve aluminium interstitial atoms, and finally (3) centers with a ∼Ev+0·27 eV level, which are K centres. These recombination centers are more or less active, depending on the initial characteristics of the sample. In the N-type silicon case, only two groups of effective recombination levels, ∼Ec−0·17 and Ev+0·3 eV, appear in the irradiated materials. However, the effects of centers possibly linked to the presence of contaminants, such as carbon and aluminium, must be added to the known effects of the divacancy, doping atom-vacancy and oxygen-vacancy complexes to explain the carrier lifetime degradation and recovery.

Method of making isolated complementary monolithic insulated gate field effect transistors

Abstract: Complementary insulated gate field effect transistors are formed in a thin semiconductor layer of a first conductivity type by first forming a dielectric layer on a surface of the semiconductor layer. A polycrystalline support is then formed on the dielectric layer. A lightly doped tub region of a second conductivity type is formed in the semiconductor layer extending to the dielectric layer. The lightly doped tub region is preferably formed by carrying out a conventional diffusion operation, then removing a portion of the thickness of the semiconductor layer which contains the highest dopant concentration. Regions serving as source and drain electrodes of a first and second field effect transistor are then formed in the lightly doped tub region and in the semiconductor layer. Gate electrodes are provided over an insulating layer on the surface of the semiconductor layer to complete fabrication of the complementary devices. The gate electrodes may be formed after the source and drain electrodes, or before them, in a self aligned embodiment.