Showing papers on "Photodiode published in 1986"

Characterization of silicon avalanche photodiodes for photon correlation measurements. 1: Passive quenching.

Abstract: We examine the photon correlation and other vital performance characteristics of silicon avalanche photodiodes operated in photon counting or the Geiger mode, and assess their suitability as detectors for photon correlation spectroscopy and laser velocimetry measurements.

Low dark current GaAs metal-semiconductor-metal (MSM) photodiodes using WSi x contacts

Abstract: We present the fabrication and characterization of metal-semiconductor-metal (MSM) photodiodes using the same undoped GaAs layer that is used as a buffer layer in the epitaxial structure for GaAs field effect transistors (FET's). To study the dark current mechanism, various metal electrodes used for Schottky contacts are examined. A drastic V-shape relationship between the dark current of MSM photodiode and the Schottky barrier height is found. An extremely low dark current (a few nanoamperes) in the MSM photodiode is obtained by using tungsten silicide as electrode metal. It is concluded that the dark current is a function of a rivalry relation between the electron injection at the cathode and the hole injection at the anode. The internal gain of the MSM photodiode with tungsten silicide contacts is found, and possible mechanisms are discussed. A flat frequency response up to 1.3 GHz is obtained. The results shows the feasibility of MSM photodiodes for use as photodetectors with low minimum detectable power, and their applicability to monolithic integration with FET circuits.

Avalanche gain in Ge x Si 1-x /Si infrared waveguide detectors

Abstract: Avalanche gain in Ge x Si 1-x /Si heterostructures photodiodes has been measured for the first time. Absorption of infrared radiation occurs in a Ge x Si 1-x /Si strained-layer superlattice (SLS) which serves as a waveguide core, and the avalanche multiplication takes place in one of the Si-cladding layers. Multiplication factors as high as 50 have been obtained for a 1.1-µm wavelength response (x = 0.2). The external absolute sensitivity operating at a multiplication of 10 is 1.1 A/W at 1.3 µm for an uncoated device.

Integrated quantum well self-electro-optic effect device: 2 × 2 array of optically bistable switches

Abstract: We demonstrate 2×2 arrays of optically bistable devices with very uniform optical characteristics. They are fabricated from an integrated self‐electro‐optic effect device structure consisting of a quantum well p‐i‐n diode grown in series with a load photodiode. Operating power can be optically controlled with a separate beam between ∼40 pW and >470 μW with associated switching times of ∼10 s and <2 μs.

Apparatus for stabilizing the optical output power of a semiconductor laser

Abstract: A drive circuit (20) supplies a semiconductor laser (l0) with current pulses corresponding to an input pulse signal (l6). A current supply (22) feeds a d.c. bias cur­rent to the laser (l0). A monitoring photodiode (l2) produces a light detection signal indicative of the actu­al laser output level. The detection signal is supplied to a subtraction device (28), to which the pulse signal (l6) is also supplied via a low-pass filter (32). The subtraction device (28) detects the difference between the two signals to produce an error signal. Integration devices (36, 48) produce average value signals (38, 50), which are compared by comparators (40, 52) with reference voltages (Vrl, Vr2) to obtain control signals (24, 54). The current supply and the current drive circuit are re­sponsive to these control signals to independently mod­ulate the d.c. bias current and the amplitude of the drive pulses applied to the laser (l0), whereby the laser output level can be stabilized to remain at a constant level.

Ge0.6Si0.4 rib waveguide avalanche photodetectors for 1.3 μm operation

Abstract: Performance of strained‐layer superlattice Ge0.6Si0.4 waveguide avalanche photodetectors is evaluated for optical fiber applications at 1.3 μm. These devices are grown on Si substrates by molecular beam epitaxy. Waveguiding is accomplished by means of a 1.5–1.8‐μm‐thick Si rib waveguide which provides an effective index step of δn=8×10−3. The detector response bandwidth exceeds 8 GHz at a gain of 6. A receiver sensitivity of ηP=−29.4 dBm has been obtained at the data rate of 800 Mb/s with the corresponding error‐free transmission over 45 km of single mode fiber.

Balanced dual-detector receiver for optical heterodyne communication at Gbit/s rates

Abstract: A balanced dual-detector receiver which requires low local-oscillator power has been designed and fabricated for optical heterodyne detection at 1·5 ?m wavelength and Gbit/s rates. The receiver consists of two InGaAs PIN photodiodes connected with opposite polarities to a high-impedance GaAs FET amplifier. Frequency response, noise suppression and noise spectrum measurements are reported.

Semiconductor laser device.

Abstract: A semiconductor laser device includes a base, a semiconductor laser chip and a resin layer enclosing the semiconductor laser chip. The base may have a monitor photodiode chip mounted thereon in the vicinity of the semiconductor laser chip. The resin layer enclosing the semiconductor laser chipor both of the semiconductor laser chip and the monitor photodiode chip is made of a single synthetic resin having a thickness not greater than 500µm and also having a surface substantially parallel to an outwardly oriented beam emitting end face of the semiconductor laser chip.

Monolithic four-channel photodiode/amplifier receiver array integrated on a GaAs substrate

Abstract: A four-channel optoelectronic integrated receiver array operating at the wavelength near 850 nm has been fabricated on a single GaAs substrate by using metal-semiconductor-metal (MSM) photodiodes (PD's) and metal-semiconductor field-effect transistors (MESFET's). The largest integration scale for a monolithic receiver and uniform characteristics among circuit channels have been achieved due to the structural simplicity and the process-compatibility of this array. Also, an extremely small capacitance of MSM-PD, 0.10 pF, has lead us to obtain a high-speed operation up to a bit rate of 1.5 Gbit/s, NRZ, and a low noise characteristic exhibiting an equivalent input noise current as small as 5 pA/Hz1/2. These results have indicated the suitability of MSM-PD/MESFET's circuits for large-scale multichannel optoelectronic integration of receivers.

Characterisation of frequency response of 1.5 μm InGaAsP DFB laser diode and InGaAs PIN photodiode by heterodyne measurement technique

Abstract: The frequency response of an InGaAs PIN photodiode and the ratio of the frequency modulation (FM) index to the intensity modulation (IM) index of a 1.5 μm InGaAsP vapour-phase-transported DFB laser diode have been measured by an optical heterodyne measurement technique. From the response of the photodiode to the laser radiation beat frequency, a 20 GHz detector bandwidth is determined. The ratio of the FM and IM indices at 3 mW laser output power per facet decreases from 60 at 100 MHz modulation frequency to 3.3 above 2 GHz.

Gate‐controlled Hg1−xCdxTe photodiodes passivated with native sulfides

Abstract: The properties of ion‐implanted junctions in Hg1−xCdxTe with x=0.22, passivated by a novel native sulfide technique, are described. The junctions are typically operated at 77 K, with 50% responsivity at a wavelength of 10.5 μm. To study the effects of the passivated surface on the diode properties, special gate‐controlled diodes were processed, including both nickel and titanium gate metals. In addition, a novel enhancement mode metal–insulator–semiconductor field‐effect transistor (MISFET) is presented. The measured dc properties and noise current spectral densities of various diodes as a function of reverse bias and gate control voltage show that close to background limited devices may be realized with the above surface passivation. In particular, such diodes exhibit good 1/f noise performance at low frequency, with reverse bias of close to 200 mV, without requiring a special gate electrode.

Two-photon digital imaging of CO in combustion flows using planar laser-induced fluorescence.

Abstract: Two-dimensional imaging of CO distributions in combustion gases is demonstrated using planar laser-induced fluorescence. The illumination technique is based on the combination of a nonlinear absorption scheme, in which two photons at 230.1 nm excite several rotational transitions of the B (1)Sigma(+) ? X(1)Sigma(+) system, and the use of an ultraviolet multipass cell for producing the laser sheet. The subsequent visible fluorescence (B(1)Sigma(+) ? A (1)Pi) is imaged onto an intensified two-dimensional photodiode array. Experimental results are presented for carbon monoxide-air and methane-air flames.

Variably spaced superlattice energy filter, a new device design concept for high-energy electron injection

Abstract: A new variably spaced superlattice energy filter is proposed which provides high‐energy injection of electrons into a bulk semiconductor layer based on resonant tunneling between adjacent quantum well levels which are brought into alignment by an applied bias. Applications of this concept to a variety of optoelectronic devices and to thin‐film electroluminescent devices and photodetectors are discussed.

Infrared light scattering tomography with an electrical streak camera for characterization of semiconductor crystals

Abstract: An electrical streak camera has been developed for IR imaging. Integration for noise reduction and subtraction of dark current were successfully performed using a 16‐bit personal computer, improving the signal‐to‐noise ratio of a PbO–PbS visicon for IR detection. In this paper, the camera was applied to infrared light‐scattering tomography for characterization of semiconductor crystals such as GaAs, InP, and CdTe crystals. In this streak camera, the IR detector can be replaced by a photodiode array such as HgCdTe, to detect even much longer wavelength radiation, which will be useful to study some electronic centers in semiconductors.

Reflective photometry instrument

Abstract: A relative reflectivity photometry instrument is provided for measuring surface reflectance as a measure, for example, of surface roughness of a specimen. The instrument includes a housing or barrel having a source of light at one end and a pair of photosensors such as photodiodes at the other end, one of which is positioned to receive rays directly from the light source and the other of which is oriented in a different direction to receive light only after the rays from the light source have struck the specimen and are scattered back onto the second sensor. Typically, the light source is mounted at the top of a barrel with the photodiodes positioned at the lower end of the barrel. The photodiodes are provided with a central opening through which a portion of the bundle of rays passes onto the specimen and is thereafter reflected onto the photosensitive surface of the second diode. Circuitry is provided for amplifying and comparing the signals received the first and second photosensitive surfaces. The comparing circuit can comprise a divider circuit for establishing a ratio between the signals from the first and second photodiodes.

Coaxially mounted 67 GHz bandwidth InGaAs PIN photodiode

Abstract: We report high-speed measurements of an InGaAs PIN photodiode in a millimetre-wave coaxial mount. The photodiode has an impulse response (including diode, parasitics and connector) of 9 ps FWHM and a 3 dB bandwidth of 67 GHz. This is the largest bandwidth reported to date for a photodiode in a coaxial mount with a connector.

Theory of the doped quantum well superlattice APD: A new solid-state photomultiplier

Abstract: A new superlattice avalanche photodiode structure consisting of repeated unit cells formed from a p-i-n Al 0.45 Ga 0.55 As region immediately followed by near intrinsic GaAs and Al 0.45 Ga 0.55 As layers is examined using an ensemble Monte Carlo calculation. The effects of various device parameters, such as the high-field layer width, GaAs well width, low-field AlGaAs layer width, and applied electric field on the electron and hole ionization coefficients is analyzed. In addition, the fraction of electrons which ionize in a spatially deterministic way, at the same place in each stage of the device, is determined. As is well known, completely noiseless amplification can be achieved if each electron ionizes in each stage of the device at precisely the same location while no holes ionize anywhere within the device. A comparison is made between the doped quantum well device and other existing superlattice APD's such as the quantum well and staircase APD's. It is seen that the doped quantum well device most nearly approximates photomultiplier-like behavior when applied to the GaAs/AlGaAs material system amongst the three devices. In addition, it is determined that none of the devices, when made from GaAs and AlGaAs, fully mimic ideal photomultiplier-like performance. As the fraction of electron ionizations per stage of the device is increased, through variations in the device geometry and applied electric field, the hole ionization rate invariably increases. It is expected that ideal performance can be more closely achieved in a material system in which the conduction band edge discontinuity is a greater fraction of the band gap energy in the narrow-band gap semiconductor.

Collection efficiency and crosstalk in closely spaced photodiode arrays

Abstract: Lateral diffusion of carriers in closely spaced photodiode arrays leads to image degradation. The effect is analyzed for backside illuminated arrays in the limiting cases of very small and very large optical absorption lengths. It is concluded that closely spaced two‐dimensional arrays for thermal imaging applications will require the use of semiconductors whose thicknesses are less than the diameters of the photodiodes.

Picosecond optical mixing in fast photodetectors

Abstract: We report a simple optical correlation technique which is capable of measuring the intrinsic response speeds of fast photosensitive electronic devices. The appeal of the method is that neither high‐speed electrical connections to a device nor cross‐correlation measurements between two devices are required. An example is given of measurements of the response speed of a GaAs Schottky barrier photodiode. Under appropriate illumination conditions the detector is found to be sufficiently fast to be capable of replacing optical second harmonic generation techniques for monitoring the quality of a beam of 1.5 ps pulses.

Bidirectional optoelectronic component operating as an optical coupling device

Abstract: The invention concerns bidirectional optical fiber connections, and more particularly an optical coupling device between an emitting electroluminescent diode and a detecting photodiode, the optoelectronic component according to the invention comprising an electroluminescent diode called DEL sealed in a box of the transistor box type the cover of which carries a microlens centered on the optical axis of the box, while inside the box are integrated: a photodiode mounted at the side of the DEL and outside the optical axis, a semitransparent mirror and a mirror support, this support being machined so as to form a second mirror that reflects light to be detected towards the detecting diode; the novel component can be used in bidirectional optical connections, in computers and telephone exchange centers.

Light scattering particle detector for wafer processing equipment

Abstract: A particle detector includes a laser, a beam shaping lens, and a pair of mirrors which reflect the shaped laser beam back and forth between the mirrors a selected number of times in order to create a sheet of light or light net between the mirrors. The path of the beam is terminated by a beam stop which contains a photodiode to monitor beam intensity and thereby system alignment. Light scattered by a particle falling through the sheet of light is gathered and transmitted to a photodiode. A peak detector provides a measure of the peak intensity of light scattered by such a particle to a microprocessor, which counts the number of particles falling through the light net in a selected time interval. The microprocessor also uses the peak intensity to estimate the size of the particle.

High-speed GaInAsSb/GaSb PIN photodetectors for wavelengths to 2.3 μm

Abstract: Front-illuminated diffused-junction PIN mesa photodiodes for use at wavelengths up to 23 pm are described The impulse response is 160 ps FWHM at −10 V bias, and the external quantum efficiency is 56% The detector responds to pseudorandom modulation at bit rates up to 2 Gbit/s

Optical monitoring method and apparatus

Abstract: Monitor signals are produced which are qualitative or quantitative measures of the shape, size or position of a light spot on an optical head relative to fibre-optic receptors in the optical head. One pair or two pairs of receptors may be used. Production of the monitor signals involves modulating the incident light forming the light spot at a predetermined frequency, delaying the light signals in one or more of the fibre-optic receptors relative to the light signals in one or more of the other receptors by, say half a wavelength of the predetermined frequency, combining the outputs of the fibre-optic receptors to produce a compound light signal, producing an equivalent compound electrical signal by means of a photodiode, and processing the compound electrical signal in electronic processors to extract one or more of its components to act as the monitor signals. Use of the invention is particularly in the monitoring of relative displacements involving optical systems which image a light source on one object onto an optical head on another object, thereby forming the light spot whose shape, size, or position alters according to the relative displacement between the two objects and the type of optical system used.

Time and frequency response of the conventional avalanche photodiode

Abstract: An analytical expression for the time course of the average impulse response function for a conventional avalanche photodiode is derived. Delta-function absorption of a single photocarrier and single-carrier-initiated/single-carrier multiplication conditions are assumed. The result is obtained as a limiting case of a previously derived equation for the staircase avalanche photodiode. The initial exponential growth of the curves is shown to represent electron and hole contributions arising from multiplication in the avalanche region whereas the subsequent exponential decay arises from residual holes transiting backward across the multiplication region. The associated frequency response function is obtained by Fourier transformation. The analytical results are shown to be in good accord with average impulse response functions obtained by Riad and Hayes by means of simulation from the transport equations. The results should also apply to the channeling avalanche photodiode and to related structures in which the carriers are spatially separated and the multiplication is essentially single-carrier like.

Indium tin oxide/GaAs photodiodes for millimetric-wave applications

Abstract: In the letter we describe improved ITO/GaAs photodiodes for very high-speed applications. For the first time a GaAs device is reported which combines a millimetric wavelength response with a - 3dB bandwidth of ≥ 50 GHz (10 ps FWHM), with a high quantum efficiency in excess of 30% at 820 nm.

Reliability of InGaAs/InP long-wavelength p-i-n photodiodes passivated with polyimide thin film

Abstract: The long-term reliability of InGaAs/InP p-i-n photodiodes passivated with polyimide thin film was studied through a room temperature life test and through thermally accelerated life tests. No degradation in dark current was observed in a room temperature life test at a reverse bias of -15 V after aging for 7000 h. However, the dark current increased gradually in the accelerated life tests at 110°C, 130°C, and 150°C. It was confirmed that the activation energy of degradation in dark current was 0.85 eV and the average lifetime was estimated to be 107h at room temperature. The dark current recovered in high temperature storage tests. The phenomenon of degradation and recovery was qualitatively explained by a model of accumulation and diffusion of mobile ions at a junction perimeter.

Computer modeling of carrier transport in (Hg,Cd)Te photodiodes

Abstract: A numerical technique has been used to solve the carrier transport equations for several (Hg,Cd)Te photodiode configurations, namely n+pp+, n+np, and pin. Of particular interest are the fundamental recombination mechanisms of radiative and Auger. Results clearly demonstrate the importance of Auger type 1 and 7 mechanisms on the n and p sides of the junction, respectively, in limiting carrier lifetimes. For example, it was found that for defect‐free Hg1−xCdxTe alloys with x=0.2 and hole concentration less than 4×1014 cm−3 adjacent to the depletion region, the Auger recombination rate can be reduced below the radiative rate. An analysis of the spatial dependence of the electron mobility shows that the presence of high carrier concentrations and electric field strengths can reduce the mobility and consequently have an effect on the sensitivity and temporal response of the photodiode.

Digital pulse position modulation over optical fibres with avalanche photodiode receivers

Abstract: The question of performance evaluation in digital pulse position modulation (PPM) transmitted over slightly dispersive optical fibres and detected by avalanche photodiodes (APD) is considered. In view of numerical complexity implicit in exact average error probability evaluation, a bound on this probability is derived. Making use of this bound we conclude that optical fibre PPM receivers based on APDs offer some improvement over optical fibre PPM receivers based on PINFETs and a big improvement when compared with PCM receivers.