Showing papers on "Diode published in 1978"

Picosecond pulse generation with a cw GaAlAs laser diode

Abstract: We report the generation of 20‐ps optical pulses at microwave repetition rate from a GaAlAs double‐heterostructure diode operating cw at room temperature The diode is operated in an external optical resonator and is actively modulated at 3 GHz The pulses are measured by autocorrelation using SHG in LiIO3 They are the shortest pulses ever reported for a cw laser diode

Hot-electron emission from silicon into silicon dioxide

Abstract: Recent progress in the study of hot-electron emission from silicon into silicon dioxide is discussed. Experimental techniques include avalanche injection using gated diodes and MOS capacitors, nonavalanche injection using IGFET structures with an underlying supply p - n junction, and optically induced injection using silicon-gate IGFET structures. IGFET structures allow the fields in the SiO2 layer and in the silicon depletion region to be varied independently. In addition, IGFET structures of reentrant geometry allow absolute emission probabilities of the hot electrons to be determined. Such absolute emission characteristics are useful not only for designing silicon devices but also for quantitative testing of theoretical models of the emission process. Several mechanisms of importance in the emission process have been identified. These are the Schottky lowering of the emission barrier, the scattering of hot electrons in the image-force potential well in the SiO2 layer, the tunneling of hot electrons, and the effect of lattice temperature on electron heating. There is also experimental evidence of the dependence of the hot-electron distribution on electric field gradient. At present, only phenomenological models based on the lucky-electron concept have been developed to the point where quantitative comparison with experimental results is possible. The essential features of these models are discussed.

Radiation imaging apparatus

Abstract: of the Disclosure Radiation imaging apparatus especially suited for use in a computerized tomographic (CT) scanner employs an array of discrete X-ray sources, each being a cold cathode diode and an adjacent fixed array of closely packed radiation detectors to produce images of rapidly moving body organs such as the beating heart A variety of alternative X-ray source embodiments are also disclosed

High-voltage converter circuit

Abstract: An inverter circuit includes a DC voltage supply having a plurality of voltage taps coupled via (1) a first plurality of diodes for unidirectional current flow therefrom to successive common connections between the upper half of a plurality of first transistors connected in cascade across the voltage supply, (2) a second plurality of diodes for unidirectional current flow therefrom to successive common connections between the upper half of a plurality of capacitors, of like number to the first transistors, connected in series and across the DC voltage supply via a pair of diodes providing unidirectional current between the voltage supply and capacitors, (3) a third plurality of diodes for unidirectional current flow thereto from successive common connections between the lower half of the plurality of first transistors, (4) a fourth plurality of diodes for unidirectional current flow thereto from the successive common connections between the lower half of the plurality of capacitors; and a plurality of second transistors connected in cascade across the series string of capacitors, their centralmost common connection being connected to an output terminal, individual ones of a fifth plurality of diodes being connected between successive common connections of the capacitors to and for unidirectional current flow (1) therefrom to the successive common connections between the upper half of, and (2) thereto from the successive common connections between the lower half, of the second transistors, the pluralities of first and second transistors being operable to different combinations of their conductive and nonconductive states for predetermined periods of time for producing a multitiered AC waveform at the output terminal.

SnO2/Si solar cells—heterostructure or Schottky‐barrier or MIS‐type device

Abstract: The performance of SnO2/Si solar cells has been measured and analyzed in detail. This has given us an insight into cell characteristics never revealed in previous studies. Though the device is a junction between two semiconducting materials, SnO2 and Si, it performs like an MIS device and in the thin‐oxide limit as a Schottky‐barrier device. The dark I‐V characteristics are attributed to a combination of thermionic and diffusion processes. The diode constant associated with the former is close to 2 or higher and that associated with the latter is unity. It has been demonstrated that under certain conditions the diode constant can be independent of the reverse‐saturation current. An MIS‐type model can explain the spectral‐response curve, the short‐circuit photocurrent, the open‐circuit photovoltage, and the light and dark I‐V characteristics. A theoretical limit of the efficiency is estimated for the device.

Cutoff Frequency of Submillimeter Schottky-Barrier Diodes

Abstract: The traditional HF model of a bulk-type (nonepitaxial) Schottky-barrier diode is extended to include the influence of skin effect, carrier inertia, and displacement current. The parasitic cutoff frequency of the extended model is calculated for n-GaAs and n-Si and compared with that predicted by the traditional model. Below the plasma frequency, the two models are found to give similar results for n-Si. For n-GaAs, however, the extended model predicts a value of cutoff frequency only one-sixth that predicted by the traditional model. With both materials, operation near the plasma frequency is impractical since it would require unrealistically small contact dimensions. Above the plasma frequency, however, both materials display a broad frequency range where operation should again be feasible. For n-Si, the extended model predicts that operation above the plasma frequency can actually be achieved with Iarger contacts than is predicted on the basis of the traditional model.

Subharmonically Pumped Millimeter-Wave Mixers

Abstract: The two-diode subharmonically pumped stripline mixer has a pair of diodes shunt mounted with opposite polarities in a stripline circuit between the signal and local oscillator inputs. The circuit has low noise and conversion loss and substantial AM local oscillator noise cancellation.The local oscillator frequency is about half the signal frequency. A novel diode chip, the notch-front diode, which has ohmic contacts on the chip faces adjacent the face containing the diode junctions, was developed for these circuits. The notch-front diode permits the low parasitic reactance of the waveguide diode mount to be achieved in stripline circuits. The best performance for a two-diode subharmonically pumped mixer with notch-front diodes was a 400 K mixer noise temperature, obtained at 98 GHz which is comparable to the best fundamental mixers in this frequency range. The performance over a 47-110-GHz frequency range for this circuit with commercial beam-lead diodes is also presented.

Method of cleaving semiconductor diode laser wafers

Abstract: Thick double heterostructure (Al,Ga)As wafers comprising layers of gallium arsenide and gallium aluminum arsenide on a metallized n-GaAs substrate are separated into individual devices for use as diode lasers. In contrast to prior art techniques employed with thinner wafers of mechanically cleaving the wafer in mutually orthogonal directions, the wafer is first separated into bars of diodes by a process which comprises (a) forming channels of substantially parallel sidewalls about 1 to 4 mils deep into the surface of the n-GaAs substrate (b) etching into the n-GaAs substrate with an anisotropic etchant to a depth sufficient to form V-grooves in the bottom of the channels and (c) mechanically cleaving into bars of diodes. The cleaving may be done by prior art techniques using a knife, razor blade or tweezer edge or by attaching the side of the wafer opposite to the V-grooves to a flexible adhesive tape and rolling the assembly in a manner such as over a tool of small radius. The diode bars may then, following passivation, be further cleaved into individual diodes by the prior art technique of mechanically scribing and cleaving. Processing in accordance with the invention results in good length definition and uniformity, high device yields and low density of striations on laser facets. The inventive process permits handling of thicker wafers on the order of 6 to 10 mils or so, which are cleaved only with great difficulty by prior art techniques. Such thicker wafers are less susceptible to breaking during handling and permit fabrication of shorter diode (cavity) length, which in turn is related to lower threshold current for device operation.

Characteristics of germanium avalanche photodiodes in the wavelength region of 1-1.6 µm

Abstract: Dark current, quantum efficiency, multiplication noise, and pulse response of germanium avalanche photodiodes with n+-p junction were studied to find an optimum structure. The dark current can be separated by graphical means into a leakage current component and a multiplied component which flows through the junction. The dark current components are also evaluated by using diodes with various diameters. The quantum efficiency and the multiplication noise are shown to be strongly affected by the n+ layer thickness. An n+ layer thickness optimized for signal-to-noise ratio is estimated from experimental and calculated results, using a figure of merit for avalanche photodiodes. The response waveform for mode-locked Nd:YAG laser shows a rise time of 100 ps and a half pulsewidth of less than 200 ps.

Noise in Solid State Devices

Abstract: Publisher Summary The purpose of this chapter is to present a survey of noise in solid-state devices. This chapter also discusses the various noise sources and this is applied to p-n junction diodes, Schottky barrier diodes, tunnel diodes, Josephson junctions, bipolar transistors, junction field effect transistors (JFETs), and metal-oxide-semiconductor field effect transistors (MOSFETs) The most important sources of noise in solid-state devices are thermal noise, shot noise, generation-recombination (g-r) noise, and flicker noise. Moreover, for semiconductor material one encounters noise due to the generation and recombination of carriers. It shows up as fluctuations in the resistance of the sample that can be detected, in turn, by applying a voltage to the sample and measuring the fluctuating current. For simple cases, the noise can be described by one fluctuating number of carriers; either electrons or holes. This is true for the noise due to traps, deep-lying donors or acceptors, Shockley-Read-Hall centers when there is a predominant lifetime.

C.W. modelocking of a GaInAsP diode laser

Abstract: Active c.w. modelocking of a GaInAsP double-heterostructure laser diode operating in an external cavity is reported. 18 ps pulses (f.w.h.m.) are obtained at a repetition rate of 2.1 GHz and a lasing wavelength of 1210 nm. The pulses were measured by autocorrelation using s.h.g. in LiIO3. They are the shortest pulses ever reported for a c.w. laser diode.

Focusing of intense ion beams from pinched-beam diodes

Abstract: Geometric focusing of proton and deuteron beams extracted from pinched-beam diodes to current densities above 70 kA/${\mathrm{cm}}^{2}$ is demonstrated by a variety of experimental techniques. Time-dependent computer simulations of the electron and ion flow show good agreement with experiment.

Properties of laser‐assisted doping in silicon

Abstract: Ohmic contacts and p‐n junctions in p‐ and n‐type silicon are generated with the aid of a laser. Doping was achieved by covering the surface of the silicon with a layer of dopant and melting locally with pulses from either a Nd : YAG or a CO2 laser. Typical residual resistances of the Ohmic contacts are of the order of 0.1–1 Ω cm2 and backward/forward resistance ratios of 104 were measured for the diodes. A model which takes account of segregation during the cooling process is discussed and shown to agree with the resulting distribution of dopant. Highly doped material was found in a surface layer of a thickness less than 0.5 μm. This thickness was independent of laser parameters.

GaAs TUNNETT Diodes

Abstract: The tunnel-injection-transit-time (TUNNETT) diode is operated at a high frequency and has a low-noise level compared to the IMPATT diode. The tunnel injection in a thin carrier generating region of the TUNNETT depends strongly on the electric-field intensity over 1000 kV/cm where the ionization of carriers can be neglected, leading to a higher efficiency performance than that of the IMPATT. GaAs TUNNETT diodes with p+-n and p+-n-n+ structures have been fabricated by a new LPE method (the temperature-difference method under controlled vapor pressure). The fundamental oscillation at frequencies from about 100 up to 248 GHz has been obtained from the pulse-driven p+-n-n+ diodes. This paper describes the details of the oscillation characteristics of GaAs TUNNETT diodes.

Diffusion length and lifetime determination in p-n junction solar cells and diodes by forward-biased capacitance measurements

Abstract: A new method is described and illustrated for determining the value and the temperature dependence of the minority-carrier diffusion length and lifetime in the base region of p-n junction solar cells and diodes. The method applies to devices after the p-n junction is formed, and thus includes the influence of the junction fabrication on the diffusion length and lifetime. The method requires only forward-biased capacitance measurements at the device terminals. It combines the dependencies of the low-frequency and high-frequency capacitance on forward bias in such a way as to yield the component of the capacitance associated with the minority carriers in the quasi-neutral base region. From this quasi-neutral-base capacitance the minority-carrier diffusion length and lifetime are then deduced. The accuracy of this method is estimated to be ±5 percent based on the accuracy of the capacitance bridges and of the measured temperature. To illustrate the method and its accuracy, it is applied to a set of silicon p-n junction diodes having base doping concentrations ranging from about 1014to 1018cm-3, and the values of the diffusion lengths determined by the capacitance method are compared with those obtained using the current response to X-ray excitation. Excellent agreement is seen. In contrast, the open-circuit-voltage-decay method yields values of the diffusion length that differ appreciably from those determined by the capacitance and X-ray methods. The reasons for the relative inaccuracy of the open-circuit-voltage-decay method applied to silicon devices are discussed. The practical limitations of the capacitance method are indicated, and an extension of the method is discussed that makes it applicable to devices having highly doped base regions and surface (emitter) layers. In such devices, the capacitance of the quasi-neutral emitter region can contribute appreciably to the total forward-biased capacitance, and the method can yield information about the material properties of the degenerately doped surface layer. The material properties determined are the phenomenological emitter lifetime and a measure of the energy bandgap narrowing in the emitter.

Light emitting diode assembly

Abstract: Light emitting diodes are mounted in an assembly of electrical leads and lenses, the leads having a common carrier strip attached thereto and pairs of resilient contact fingers, the diodes being resiliently gripped between pairs of contact fingers and then encapsulated in a light transmitting material which itself forms a diffusing lens; a separate lens alternatively being provided by a rigid outer shell of light transmitting material.

Silicon carbide blue-emitting diodes produced by liquid-phase epitaxy

Abstract: Silicon carbide light-emitting diodes with emission in the blue range of the spectrum have been produced by two versions of the LPE process. Emission spectra and efficiency data are presented for diodes with different impurity levels. The highest external quantum efficiency observed so far at room temperature is 4 × 10 −5 . The highest luminosity is 0.5 mcd at 100 mA, corresponding to a current density of 20 A/cm 2 and a beam of about one steradian. A brightness of 15 ftl/A/cm 2 is obtained.

Deep traps in ideal n-InP Schottky diodes

Abstract: A number of deep electron trap levels have been detected in bulk and epitaxial InP for the first time. These deep traps are located in the upper half of the bandgap, and have been observed in Schottky barrier diodes by transient capacitance spectroscopy (d.l.t.s.). The deep traps have been shown to be responsible for low frequency excess noise in the Schottky diodes.

Method for forming p-n junctions and solar-cells by laser-beam processing

Abstract: This invention is an improved method for preparing p-n junction devices, such as diodes and solar cells High-quality junctions are prepared by effecting laser-diffusion of a selected dopant into silicon by means of laser pulses having a wavelength of from about 03 to 11 μm, an energy area density of from about 10 to 20 J/cm 2 , and a duration of from about 20 to 60 nanoseconds Initially, the dopant is deposited on the silicon as a superficial layer, preferably one having a thickness in the range of from about 50 to 100 A Depending on the application, the values for the above-mentioned pulse parameters are selected to produce melting of the silicon to depths in the range from about 1000 A to 1 μm The invention has been used to produce solar cells having a one-sun conversion efficiency of 106%, these cells having no antireflective coating or back-surface fields

Narrow band-gap semiconductor CCD imaging device and method of fabrication

Abstract: A monolithic charge-coupled infrared imaging device (CCIRID) is fabricated on N-type HgCdTe. A native oxide layer on the semiconductor is used, in combination with ZnS to provide first level insulation. An opaque field plate over first level insulation is provided for signal channel definition. Second level insulation (ZnS) is substantially thicker than the first level, and is provided with a stepped or sloped geometry under the first level gates. Input and output diodes are provided with MIS guard rings to increase breakdown voltages.

Plasma x‐ray emission produced by ruby lasers at 1012 W/cm2

Abstract: Q‐switched 20‐nsec ruby‐laser pulses (∼05 GW) were focused to about 1012 W/cm2 on targets containing elements in the range 6⩽Z⩽68 Time‐ and space‐integrated x‐ray emission from plasmas 200 μm in diameter with lifetimes near 12 nsec was measured with four active detectors at energies between 01 and 5 keV Maxima in x‐ray intensity measured by each detector occurred when binding energies of core electrons in target atoms were 20–30 times the electron plasma temperature Calculated detector response functions together with coronal‐model plasma emission computations were used to analyze the atomic‐number dependence of the detector signals A plasma electron temperature of 70 eV and an electron density of about 4×1020 cm−3 gave the best fit to the ratios of signals Computed spectra for this temperature showed that the peaks in the low‐energy detector (an x‐ray diode most sensitive near 015 keV) were due in part to line radiation Peaks in the three detectors sensitive above 1 keV (two silicon PIN diodes and an ionization chamber) were primarily due to recombination radiation The results of this work augment an earlier similar, but limited, study at 1012 W/cm2

Power failure light and circuit therefor

Abstract: A power failure light for monitoring a power line and for illumination upon the interruption of power therefrom includes a light bulb, a rechargeable battery, a power supply providing charging current for the battery, a pair of diodes connecting the battery across the power supply, a pair of cascaded transistors connecting the bulb across the battery with the base-emitter junctions of the transistors connected across the diodes to thereby sense the condition of the power line. The base-emitter junctions are reversed biased by the pulsating voltage across the diodes, and a timing network, including a resistor across the power supply and a capacitor across the diodes, maintains the reverse biased condition of the junctions between the voltage pulses.

Diode capable of alternately functioning as an emitter and detector of light of the same wavelength

Abstract: The invention relates to a diode capable of alternately operating as a detector and emitter of light in the same frequency band. This diode comprises an active zone disposed between two localizing zones and respectively forming two hetero-junctions with these zones. The reverse biassing voltage is such that the active zone is the seat of the avalanche phenomenon.

Electronic Circuits for High Bit Rate Digital Fiber Optic Communication Systems

Abstract: This paper describes electronic components for digital fiber optic transmitters and receivers with bit rates from several hundred Mbits/s up into the Gbits/s range. In particular, drivers and multiplexers suitable for direct laser modulation were developed for use in the transmitter units. A laser light output control circuit for independent stabilization of the minimum and peak to peak laser light output levels is described. A demultiplexer and clock regenerator circuit was developed for optical receivers. All high speed components were realized in thin film hybrid integrated technology using silicon bipolar transistors, Schottky diodes and step recovery diodes.

Universal solar cell/conductor junction element and solar panel embodying same

Abstract: A solar electric power generating panel (solar panel) includes one or more universal electrical junction elements of approximately the same size and shape as conventional solar cells mounted along with the cells on a solar array substrate at any selected cell position or positions of the cell array. Each junction element has terminals which may be electrically connected to interconnects of the solar cells and electrical conductors such as lead wires of the cell array in such a way as to condition the element to serve as a series string termination with or without blocking diodes, an electrical voltage tap with or without blocking diodes, or a mounting for cell shunting diodes. Automatic assembly tooling may be utilized to assemble and electrically connect the solar cells, conductors, and junction elements into a completed solar array.