Showing papers on "Photodiode published in 1983"

Silicon photodiode device with 100% external quantum efficiency

Abstract: A device utilizing four inversion layer photodiodes in a light-trapping arrangement was constructed and tested. The device was found to have a photon-to-electron conversion efficiency of 0.999 for short wavelength and low power visible radiation. It was found that applying a reverse bias voltage extended the high quantum efficiency response over the entire visible spectrum and up to the highest radiant power level studied (several milliwatts). Several radiometrically important characteristics were studied and the results presented: spectral reflectance; polarization sensitivity; quantum efficiency vs wavelength, photon flux density, and reverse bias voltage; and dark current vs reverse bias.

Staircase solid-state photomultipliers and avalanche photodiodes with enhanced ionization rates ratio

Abstract: The theory of the staircase avalanche photodiode (APD) is presented and recent results on a new class of APD's with enhanced ratio of ionization coefficients are reviewed. The staircase APD consists of a multistage graded gap structure where only electrons ionize; the entire ionization energy is provided by large conduction band steps (dynodes). A general expression for the excess noise factor F in terms of the number of stages and the multiplication per stage is presented. For high ionization yields per dynode the F factor is near unity independently of the number of stages, implying virtually noise free multiplication at high gain similar to a photomultiplier. This cannot be achieved in a conventional APD at high gain even if one of the ionization coefficients is zero. A comparison between the noise behavior of the staircase APD and that of a phototube is also presented. A microscopic theory of the ionization yield γ is discussed; to obtain a high γ electrons must approach the dynode with an energy in the order of ten times the optical phonon energy. The possible problem of residual hole-initiated ionization is also discussed. Formulas for the electron and hole initiated multiplications are derived; from a measurement of these quantities one can directly obtain the ionization yield and the residual hole ionization coefficient. Experimental and theoretical results on other structures (superlattice, channeling, graded gap APD's) with high \alpha/\beta ratio are also reviewed and design considerations for a long-wavelength multilayer APD are presented.

High-performance avalanche photodiode with separate absorption ‘grading’ and multiplication regions

Abstract: High-speed operation of avalanche photodiodes with separated absorption and multiplication regions has been achieved by incorporating an intermediate bandgap InGaAsP ‘grading’ layer between the InP multiplication layer and the InGaAs absorption layer. These APDs also exhibit low dark currents, high quantum efficiencies and good avalanche gains. Sensitivity measurements have been made at 1.3 μm and 1.55 μm with one of these APDs in a high-speed optical receiver: at bit rates of 420 Mbit/s and 1 Gbit/s the minimum average powers required for 10−9 BER are −43 dBm and −38 dBm at 1.55 μm, and −41.5 dBm and −37.5 dBm at 1.3 μm, respectively.

100 GHz bandwidth planar GaAs Schottky photodiode

Abstract: In the letter we report the development and characterisation of a planar-structure GaAs Schottky-barrier photodiode whose response to a mode-locked laser pulse of 600 nm wavelength has a full-width half-maximum of 5.4 ps and a 3 dB bandwidth of 100 GHz.

17‐GHz bandwidth electro‐optic modulator

Abstract: A high‐speed integrated‐optic Ti:LiNbO3 Mach–Zehnder interferometric modulator for 0.83‐μm wavelength operation has been fabricated and characterized. The modulator exhibits smooth, resonance‐free frequency response with a 17‐GHz 3‐dB bandwidth. The modulator has a built‐in phase bias of π/2 for maximum linearity. Complete intensity modulation can be achieved with 120‐mW drive power. Optical modulation was measured up to 18 GHz directly by using a very high‐speed photodiode and indirectly using the swept frequency technique.

Band‐gap engineering via graded gap, superlattice, and periodic doping structures: Applications to novel photodetectors and other devices

Abstract: Recent new multilayer structures and their device applications are reviewed. These new concepts allow one to radically modify the conventional energy band diagram of a pn junction and thus tailor the high field transport properties to an unprecedented degree (band‐gap engineering). This approach has been used to propose and implement a new class of avalanche photodiodes with enhanced ionization rates ratio and the solid state analog of a photomultiplier (staircase detector). Other device applications such as repeated velocity overshoot structures are also discussed.

Infrared reflectance densitometer

Abstract: An integral, compact infrared reflectance densitometer including a substrate supporting an LED, a control photodiode to compensate for component degradation, a background photodiode to compensate for background radiation, and a large area photodiode to provide an electrical signal representative of the amount of toner particles on the photosensitive surface. Also carried on the substrate is a field lens to focus light rays reflected from the photosensitive surface onto the signal photodiode. The substrate is precisely secured to a molded housing having integral collector and collimating lenses. Four extending pins on the housing engage four apertures on the substrate to locate the substrate with respect to the housing and align the LED and field lens carried on the substrate with the collector and collimating lenses of the housing. Also carried on the substrate is an aperture box to permit a portion of the LED light to project through the collimating lens to the photosensitive surface and a portion of the light to be reflected onto the control photodiode to control light output. The light rays reflected from the photosensitive surface are gathered in a collector lens and projected through the field lens to be focused onto the signal photodiode. An L-shaped clip and an appendage with an elongated aperture extend from opposite ends of the housing to position and align the infrared reflectance densitometer in the reproduction machine with respect to the photosensitive surface.

20‐GHz bandwidth GaAs photodiode

Abstract: A high‐speed GaAs Schottky barrier photodiode with 3‐dB bandwidth of 20 GHz, an external quantum efficiency at 600 and 845 nm of ≥25%, and operating at less than 5‐V reverse bias is reported. Accurate characterization of these devices in both the time and the frequency domains is discussed.

Impact ionization in (100), (110), and (111) oriented InP avalanche photodiodes

Abstract: The impact ionization process in the 〈100〉, 〈110〉, and 〈111〉 crystallographic directions in InP has been investigated by analysis of photomultiplication and multiplication noise data from InP avalanche photodiodes. This is the first report of such measurements for (110)‐oriented InP and the first consistent investigation of impact ionization in the three principal crystallographic directions. Our measurements indicate that, unlike the reports for GaAs, no significant orientation dependence of the impact ionization coefficients exists in InP. Momentum‐randomizing collisions with phonons, which result in intervalley transfer of energetic electrons, are believed to be the reason for the lack of anisotropy in the electron impact ionization coefficients.

Analysis of the dark current and photoresponse of In0.53Ga0.47As/InP avalanche photodiodes

Abstract: The doping profiles, current-voltage (I–V) and photoresponse characteristics of five In0.53Ga0.47As/InP avalanche photodiode (APD) wafers are presented. A detailed analysis indicates that the dark current is due largely to generation and recombination of carriers in the diode bulk, and in some wafers tunneling at the p-n junction is dominant near breakdown (VB). In some cases, significant surface currents are also observed. In three high-performance wafers, however, low primary dark currents (∼5 nA) with no evidence for tunnelling at 0.99 VB have been obtained. In addition, microplasmas have been found in some wafers, due to local breakdown possibly arising from crystalline defects. Nevertheless, we report uniform gains as high as 100. The dark current and gain characteristics of these devices are among the best reported to date for In0.53Ga0.47As/InP APDs. Finally, the response of the APDs to fast optical pulses has been analyzed at both low and high illumination intensity. The slow speed of response, which has been reported elsewhere, is considered in detail and is found to be due to charge pile-up at the abrupt n-In0.53Ga0.47As/n-InP heterointerface which is characteristic of our devices. Using an analysis of the response time thermal activation energy along with the transient pulse shape, we infer that the heterointerfaces are graded over a length of 2 L ≌ 300 A . The model predicts that fast response can be obtained for heterointerface grading lengths of 2 L ⩾ 500 A , depending on the epitaxial layer doping and extent of penetration of the depletion region into the In0.53Ga0.47As layer at breakdown.

Planar monolithic integration of a photodiode and a GaAs preamplifier

Abstract: A monolithic optical receiver chip consisting of a pin photodiode and a transimpedance preamplifier on a GaAs semi‐insulating substrate is reported. The epitaxial layers for the photodiode are grown by hydride vapor phase epitaxy and the circuit elements are fabricated by selective ion implantation in the semi‐insulating substrate. The integration scheme results in a planar surface which simplifies the processing of optoelectronic integrated chips.

Photosensor array device

Abstract: A photosensor array device comprises a line sensor including a plurality of sets of sensors juxtaposed on a transparent glass substrate. Each set comprises an amorphous silicon photodiode, a crosstalk preventing element in the form of a diode or a transistor and a matrix wiring connected to the element. A selector is provided for driving the crosstalk preventing elements of the line sensor. The photodiode and the crosstalk preventing element are formed integrally.

Ultrahigh speed modulation‐doped heterostructure field‐effect photodetectors

Abstract: We have developed a sensitive, ultrahigh speed photodetector which has a structure of a modulation‐doped AlxGa1−xAs/GaAs field‐effect transistor. In spite of a large gate‐drain spacing of >8 μm and a gate length of >20 μm, this detector exhibited a rise time of 12 ps and a full width at half‐maximum of 27 ps. When tested by a 8200‐A GaAs injection laser, the detector showed an ac (>20 MHz) external quantum efficiency of >630%, i.e., 9 times more sensitive than a pin photodiode. In view of its high sensitivity, ultrahigh speed, and compatibility with modulation‐doped field‐effect transistors, this detector has promise for a variety of high‐speed optical applications.

Asymmetric Abel Inversions on Inductively Coupled Plasma Spatial Emission Profiles Collected from a Photodiode Array

Abstract: The utility of a photodiode array based spatial emission profiling system has been enhanced by using a method for performing an Abel inversion on asymmetric lateral data which preserves the asymmetry in the radial emission profiles. This procedure has been implemented with an APPLE II plus computer, coupled with a Reticon RL-1024S photodiode array that has been masked with a narrow exit slit. The method has been tested with a theoretical set of lateral data and with actual measured spatial emission profiles.

P-i-n and avalanche photodiodes

Abstract: High-speed p-i-n and avalanche photodetectors (photodiodes) use a heavily doped buried layer to greatly limit minority carriers generated by incident light in the buried layers and the substrates of the devices from reaching the cathodes and thus enhances response time while substantially decreasing dark current. A p-i-n diode of this type with a 1.1 square millimeter active area can operate with 4 volt reverse bias and is capable of having edge rise and fall times in the 4 nanosecond range.

A high photosensitive IL-CCD image sensor with monolithic resin lens array

Abstract: A high photosensitivity interline transfer CCD image sensor with monolithic resin lens array was developed. The resin lens array was made on the 2/3 inch scheme 768(H) × 490(V) pixels interline CCD image sensor by using the resin thermal flow technique. The resin lens array consists of a smooth base resin layer and overlaid vertical stripe semicylindrical lens array corresponding to photodiode vertical lines. The effective photodiode aperture, which was only 40% for the original device, was increased to 80% for the device with monolithic resin lens array. The photosensitivty reached 0.18 µA/µW at 550 nm, which corresponds to 0.4 quantum efficiency.

High-speed traveling-wave directional coupler switch/modulator for λ = 1.32 µm

Abstract: We have designed and fabricated a Ti:LiNbO 3 waveguide traveling-wave directional coupler switch/modulator operating at \lambda = 1.32 \mu m that exhibits a 3 dB modulation bandwidth of 7.2 GHz, a switching voltage of 4.5 V, and power per unit bandwidth of 7.6 mw/ GHz. Using short drive pulses, optical pulsewidths as short as 58 ps have been generated and directly measured with a high-speed InGaAs/InP p-i-n photodiode. Thick ( \sim 2.8 \mu m) electroplated gold has been used to produce a small gap (5 μm) and low-loss coplanar strip electrode. The 1.5 cm long, 15 μm wide electrode has a dc resistance of 7 Ω and a total microwave power loss of ∼4dB at 5 GHz.

Photon counting with photodiodes

Abstract: Preliminary results concerning the use of silicon photodiodes designed to be used in the photon counting or Geiger mode are described. These Geiger photodiodes have higher detected quantum efficiency than photomultiplier tubes over the 5000–9000-A wavelength region and are especially superior at longer wavelengths, although they can only be used in the Geiger mode at relatively low flux rates (<104/sec). Diodes operating in this mode are probably the fastest photon counting detectors in existence. The limitations and properties of Geiger diodes currently available are discussed.

Thermal lens spectrophotometry with argon laser excitation source for nitrogen dioxide determination

Abstract: In order to improve the sensitivity of thermal lens spectrophotometry, a new type of optical configuration was studied. An Ar/sup +/ laser for excitation was focused into a sample cell as usual, but a probe laser was introduced directly without focusing the beam. The laser beams were collimated and isolated with two prisms to eliminate optical interference of the laser beams. A part of the probe laser passing through the sample cell was split out by a quartz wedge and the intensity at the beam center was detected by a photodiode. The signal was measured by a digital lock-in amplifier system. The detection limit of NO/sub 2/ was 5 ppb, using the 488-nm line of the Ar/sup +/ laser (700 mW). The dynamic range of the linear analytical curve was obtained over 4 orders of magnitude. The present method has a distinct advantage over a photoacoustic method with respect to the capability of continuous monitoring of atmospheric NO/sub 2/. 5 figures, 2 tables.

The Gas Photodiode as a Possible Large-Area Photon Detector

Abstract: Testing extensively a dozen custom-manufactured gas photodiodes, we have observed stable and reproducible characteristics of the argon-filled devices at pressures around 1 Torr, with gains up to 30-40. Methane-filled diodes operate at even higher gains (60-70) at around the same pressure, and have a faster response; they show, however, long-term degradation at relatively low light fluxes. At higher pressures, while the argonfilled device is largely degraded, high quantum efficiency and a good collection plateau is observed in methane. When operated in the collection mode, the CH4 high-pressure device does not show any sign of degradation.

Surface‐tunneling‐induced 1/ f noise in Hg1−xCdxTe photodiodes

Abstract: The reverse bias dark curent of Hg1−xCdxTe (MCT) photodiodes is often dominated by tunneling across a pinched off surface depletion region. The width of this critical region may be modulated by charge exchange with slow surface states in a passivant insulator. Numerical calculations give the correct order of magnitude for observed 1/ f noise in ZnS passivated MCT photodiodes.

Solid state image pick-up device

Abstract: A solid state image pick-up device includes a number of picture elements arranged in a matrix form each picture element being constituted by a MOS transistor and a photodiode, gates of the MOS transistors arranged in a vertical direction are connected to respective horizontal scanning lines which are connected to outputs of a horizontal shift register. Drains of the MOS transistors arranged in a horizontal direction are connected to respective vertical scanning lines both ends of which are connected to first and second signal read-out lines via first and second vertical selection switches, respectively. The first and second vertical shift registers produce first and second vertical scanning pulses which are shifted by given time period corresponding to a desired shutter open time. Each picture element is scanned twice by means of the first and second vertical scanning pulses. By adjusting said time period, the shutter open time can be set at with within a wide range.

Monolithic integration of a photodiode and a field‐effect transistor on a GaAs substrate by molecular beam epitaxy

Abstract: A Schottky barrier photodiode and a field‐effect transistor (FET) have been monolithically integrated on a GaAs substrate using molecular beam epitaxy. The electronic isolation between constituent elements has been achieved by the present device structure in which a semi‐insulating substrate is used. The dark current at the punchthrough voltage as low as 8×10−10 A and a uniform quantum efficiency over the photosensitive area have been observed by the measurements. A linear amplification of the photocurrent by the FET over a wide range of incident light power has been confirmed. The amplification ratio of 19 has been achieved with a 10‐kΩ photodiode load resistor. The present result demonstrates the usefulness of molecular beam epitaxy in realizing optoelectronic integrations.

Optical rotary encoder

Abstract: An optical rotary encoder includes a slit plate having a plurality of circumferentially aligned slits of a pitch P, a light emitting diode, and a light responsive section. The light responsive section includes four photodiodes formed on a single substrate. The four photodiodes are aligned in the tangential direction of the slit plate with the interval corresponding to 1/4 P. Output signals derived from each of the four photodiodes are introduced into a detection circuit for determining the angular position and velocity of a rotating shaft to which the slit plate is secured.

Scintillation Detectors Using Large Area Silicon Avalanche Photodiodes

Abstract: Low noise, large area silicon avalanche photodiodes have now been made to replace photomultiplier tubes in certain scintillator detector applications in which overall size and ruggedness are important. Previous devices have been limited by poor optical sensitivity and very small active size. These sensors when coupled to a 1-inch NaI(T1) crystal have produced pulse height spectra with resolution for Cs 137 gamma radiation as low as 9.5% FWHM. This achievement is the result of improvements in both silicon material quality and device design. Based on these results the future prospects of such detectors are very encouraging.

Solid state relay with fast turnoff

Abstract: A solid state relay having a light-emitting diode, an array of series connected photodiodes, a field-effect-transistor (FET) and optically controlled switch for FET turn off is described. The light-emitting diode is optically coupled to the array of photodiodes. Turn on of the transistor is determined entirely by the voltage developed by the array of photodiodes. Turn off of the transistor is determined by the state of the optically controlled switch.

A numerical analysis of a heterostructure InP/InGaAs photodiode

Abstract: Electrical properties of a heterostructure InP/In 0.53 Ga 0.47 - As photodiode have been analyzed numerically. A device simulator, which can handle a heterostructure up to a high voltage operation, was developed for this work. The numerical simulator explains the experimental results obtained regarding photocurrent. The band-gap discontinuities, i.e., 0.22 eV for the conduction band and 0.37 eV for the valence band, were confirmed to be plausible. The photocurrent switching mechanism in the photodiode by bias voltage was clarified through carrier and potential distributions. It was revealed that the photo-excited holes accumulate at the heterointerface, and the switching voltage for photocurrent varies according to the incident optical power level. It is expected that this simulator will be a powerful tool for optimum heterostructure photodiode design.

Peripheral photoresponse of a p–n junction

Abstract: A quantitative theory is presented for the enhanced photoresponse of p–n junctions that arises from the lateral diffusion of photogenerated carriers. This mechanism leads to a photoactive area for a photodiode that may be much larger than its p–n junction area. The main theory pertains to the geometry that arises with mesa diodes, the results for which are also applicable to planar junctions that are shallow when compared with the minority‐carrier diffusion length. The solution for infinitely deep planar junctions is obtained by separate analysis. The magnitude of the peripheral photoresponse is sensitive to geometric and physical factors such as semiconductor thickness, surface recombination, optical absorption length, and competition for photogenerated carriers by adjacent photodiodes. The dependence of the response upon all of these features is presented.