Avalanche Photodiode Noise Research Articles

A simple model to determine multiplication and noise in avalanche photodiodes

Avalanche multiplication and noise in 1.0, 0.5, 0.1, and 0.05 μm GaAs p+-i-n+ diodes have been calculated for both electron and hole initiated multiplication using a simple model which incorporates a randomly-generated ionization path length (RPL) and a hard-threshold dead space. We find that the mean multiplication obtained using this RPL model is in excellent agreement, even for the shortest structure, with that obtained from an analytical-band structure Monte Carlo (MC) model, which incorporates soft-threshold effects. However, it predicts slightly lower avalanche noise in the shorter devices. This difference results from the narrower ionization path length probability distribution and larger dead space of the hard-threshold RPL model at high electric fields as compared to the more realistic distribution function associated with the relatively sophisticated MC model.

Avalanche photodiodes operating parameter optimization for the Frascati Tokamak Upgrade Thomson scattering system (abstract)

Measured figures (linearity, avalanche gain, frequency response, and noise) of the avalanche photodiodes (APD) detectors used on the FTU Thomson scattering system (FTU-TS) are reported. This investigation on the APD figures is motivated by the necessity of knowing their values over a wide range of input signals, and also of checking the validity of McIntyre model of APD noise, since using this model the experimental signal-to-noise ratio is calculated. From the noise analysis, a method of optimization of the detection system sensitivity is derived, leading to the optimization of the signal-to-noise ratio over the entire FTU-TS system.

Avalanche photodiodes operating parameter optimization for the Frascati Tokamak Upgrade Thomson scattering system

Measured figures (linearity, avalanche gain, frequency response, and noise) of the avalanche photodiodes (APD) detectors used on the FTU Thomson scattering system (FTU-TS) are reported. This investigation on the APD figures is motivated by the necessity of knowing their values over a wide range of input signals, and also of checking the validity of McIntyre model of APD noise, since using this model the experimental signal-to-noise ratio is calculated. From the noise analysis, a method of optimization of the detection system sensitivity is derived, leading to the optimization of the signal-to-noise ratio over the entire FTU-TS system.

Avalanche photodiodes as large dynamic range detectors for synchrotron radiation

We investigated silicon-based avalanche photodiodes (APDs) as X-ray detectors in terms of their linearity, maximum counting rates, and dynamic range with 8.4 keV synchrotron radiation. Measurements resulted in counting rates that extend from the APD's noise level of 10 −2 Hz to saturation counting rates in excess of 10 8 Hz. In addition, by monitoring the APD's noise level and photon counting efficiency between synchrotron bursts, we demonstrate nine orders of magnitude dynamic range.

Optical orthogonal code-division multiple-access system .I. APD noise and thermal noise

In an optical multiple-access system, overall system throughput efficiency add significant implementation cost-reduction would be achieved if many users could access a common optical channel at any time without control among users. Recently one such scheme, an optical orthogonal code division multiple-access system (OOCDMA), was introduced by Salehi et al. (1982) for the case of no noise. In this paper, some extensions of that work are presented, including the effects of avalanche photodiode (APD) noise and thermal noise as well as interference for the OOCDMA direct-detection receiver. Since it has been shown that an optical hard-limiter before the receiver correlator can reduce the interference effect for the OOCDMA system in the absence of noise, the hard-limiter role in the presence of thermal and APD noise is also examined. >

Modeling high-speed optical transmission systems

Computer simulation of a 2.5-Gb/s intensity-modulated/direct-detected optical system with high path dispersion is described. This simulation, based on single-mode laser diode rate equations, includes transmit and receiver circuit filtering, receiver circuit noise, avalanche photodiode noise, fiber dispersion, and laser chirp. The rate equations are sufficiently general to model mode-offset distributed feedback laser diodes. The system power penalty, due to laser chirp and fiber dispersion, is calculated using Gaussian quadrature numerical integration. By simulating a population of some 12800 laser diodes and correlating the performance of each laser in a transmission system with its spectral characteristics, it is possible to deduce laser specifications that will assure satisfactory operation in long-span links. These results are used to study a laser diode specification under consideration by CCITT, and, by studying the simulated laser line shapes, some modifications to the CCITT specification are considered. >

A low-noise, wideband, integrated CMOS transimpedance preamplifier for photodiode applications

A low-noise, wideband, integrated CMOS transimpedance preamplifier is presented for silicon avalanche photodiode (APD) applications. The preamplifier, fabricated in a standard 2- mu CMOS technology, features a transimpedance gain of 45 k Omega , a risetime of 22 ns, a series noise of 1.6 nV/Hz/sup 1/2/, and a wideband equivalent input-noise current of 12 nA for a source capacitance of 12 pF. The measured /sup 22/Na timing resolution of 9.2-ns full width at half maximum (FWHM) and energy resolution of 22.4% FWHM for the RCA C30994 BGO/APD detector module coupled to the preamplifier are comparable to the performance reported using charge-sensitive preamplifiers. This shows that transimpedance preamplifiers should be considered for APD applications, especially where APD noise current dominates noise from feedback resistors in the 10-k Omega to 50-k Omega range. The transimpedance preamplifier reported here offers advantages of being fully monolithically integrated, having low power dissipation (38 mW), having low bandwidth sensitivity to source capacitance, requiring no shaping-amplifier pole-zero compensation, and requiring no feedback capacitance reset at high count rates. >

Toward minimum ionizing particle detection using scintillating fibers and avalanche photodiodes

Scintillating fibers are potentially competitive with silicon microstrip detectors for moderately high resolution ( approximately 100 mu m) particle tracking in high-energy physics experiments. Realizing this potential requires the development of a compact, efficient, and high-speed readout. The feasibility of using avalanche photodiodes (APD) for the detection of minimum-ionizing particles in submillimeter scintillating fibers is assessed. In tests to date, the expected small signal has been overwhelmed by amplifier noise. The fact that APD noise was a negligible contribution, even at an APD gain of 300, was verified by observing that the pulse-height spectrum with and without APD bias voltage showed no difference, and the RMS width of the distribution was consistent with the amplifier noise. Contemplated improvements to the apparatus include using veto counters to restrict the qVt triggers to beta rays definitely passing through the fiber (which should improve the signal-to-noise by a factor not more than approximately=(6 mm/1 mm)=6), and constructing an adjustable mount to allow optimal centering of the fiber relative to the APD's sensitive area.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A theory of multiplication noise

A general theory of noise in avalanche photodiodes (APDs), photomultipliers, and other cascaded multiplication devices in which ionization is independent of a carrier's history is presented. The theory is based on a composition law that allows the calculation of the gain distribution of a multilayer structure from the known distributions for each layer. The composition law is used to establish some well-known results and a number of new results. New formulas are derived for the gain and excess noise of a general double-carrier structure composed of multiple identical stages. A set of differential equations is derived for the case of continuous multiplication, as in a conventional APD. New results are reported for the noise of the staircase APD and for an APD with two regions of constant but different ionization ratios. The latter can be used to model the InGaAs/InP separated absorption and multiplication APD.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Realization of a staircase photodiode: Towards a solid-state photomultiplier

Abstract A few years ago a low noise avalanche photodiode with a near unity excess noise factor was proposed. This detector achieves a high ratio of ionization coefficient κ via a suitable staircase band diagram. This APD can in principle exhibit photomultiplier-like noise behavior. In this paper we report the first realization of a staircase APD, grown in AlGaAs/GaAs by MBE, consisting of a ten-stage undoped staircase high-field region between p+ and n+ GaAs layers. Typical dark currents were 200 pA at the breakdown onset. The electron initiated avalanche gain was greater than 100 at the same voltage. Ionization ratios greater than 10 were estimated. Pulse responses with a full width at half maximum (FWHM) of 200 ps were demonstrated.

Ein schnelles Näherungsverfahren zur Berechnung der Bitfehlerwahrscheinlichkeit bei nicht-gaußschem Rauschen

A numerical method is described for calculating the bit error rate in digital transmission channels, whose noise has an asymmetric non-Gaussian amplitude distribution, such as the noise of avalanche photodiodes, for example. This method was developed for a computer program for the stimulation of fiber-optic transmission systems and can combine the effects of multiple noise sources

Impact ionisation thresholds in silicon and germanium under hydrostatic pressure and strain

We have studied experimentally and theoretically impact ionisation thresholds in the indirect band-gap semiconductors, silicon and germanium. The threshold energies for electron- and hole-initiated ionisation processes were calculated numerically using an empirical pseudopotential band-structure which includes spin-orbit interactions. In silicon, the threshold energy for holes is significantly greater than that for electrons, whereas in germanium the thresholds are almost equal. We point out the band-structure features responsible for this behaviour, and its influence on the multiplication noise of avalanche photodiodes fabricated in these materials. We have measured the breakdown voltage in silicon and germanium avalanche photodiodes while varying the band-structure using hydrostatic pressure. For silicon, the results are consistent with impact ionisation dominated by electron-initiated umklapp processes associated with the Δ minima, in agreement with the calculations. The results for germanium show experimental evidence for impact ionisation above the threshold energy (‘soft’ threshold), and for multiple ionisation processes contributing to the carrier multiplication. We have also calculated the thresholds for impact ionisation in strained silicon grown on (100) germanium, and for strained germanium grown on (100) silicon. The results show that strained layers fabricated in indirect band-gap semiconductors are potentially attractive for use in low-noise avalanche photodiodes.

Erratum: Improved figure of merit for noise in avalanche photodiodes

Erratum: Improved figure of merit for noise in avalanche photodiodes

Improved figure of merit for noise in avalanche photodiodes

We propose a new noise figure for avalanche photodiodes (APDs). This new noise figure overcomesthe difficulty of estimating the internal multiplication and quantum efficiency in complex APD structures, such as III-V SAM APDs. Measurements of the new noise figure are presented for two commercial SAM APDs and we show theoretically that it represents a more complete figure of merit for comparing the performance of one APD with another, and with the ideal.

Measurements of Natural Radiation Effects in a Low Noise Avalanche Photodiode

Low noise avalanche photodiodes were irradiated to determine their sensitivity to the natural space environment. Radiation effects on important APD parameters were determined by exposure to 1.5 MeV electrons from a Van de Graaff generator and to gamma rays from a Co60 source, both to a total dose of 300 krad (Si). During irradiation, the DC dark current and an associated 1/f noise were found to increase linearly with dose only if bias voltage was applied. A t-x annealing behavior was observed. Radiation damage coefficients, threshold dose rates, and threshold fluences are calculated.

Ballistic avalanche photodiodes: Ultralow noise avalanche diodes with nearly equal ionization probabilities

Avalanche photodiode structures are proposed which theoretically exhibit very low excess noise. In these designs, the hole and electron ionization probabilities are made very close to unity for a single pass of the multiplication region. This is accomplished by ballistic injection across the gain region. The structures are less complex than other proposed low noise avalanche photodiode structures.

New avalanche multiplication phenomenon in quantum well superlattices: Evidence of impact ionization across the band-edge discontinuity

In suitably designed superlattice structures hot carriers in the barrier layers can collide with carriers confined or dynamically stored in the wells and impact ionize them out, across the band-edge discontinuity. Photomultiplication and spectral response measurements as a function of temperature and chopping frequency in Al0.48 In0.52 As/Ga0.47 In0.53As and AlSb/GaSb superlattices provide strong evidence of this effect. The observed phenomenon is characterized by a large ratio of the multiplication factors for holes and electrons implying that β≫α and can be the basis for a new class of very low noise avalanche photodiodes and solid-state photomultipliers.

CMT: The material for fiber optical communication devices

Over many years, Hg 1 - x Cd x Te ternary alloys have been widely investigated, principally in the mercury-rich composition range, mainly for far infrared military applications. However, recent developments of fiber optical telecommunication systems have led to a great interest in near infrared transmission links at 1.3 and 1.55 μm or higher. Cadmium mercury telluride (CMT) alloys in the cadmium-rich composition range have proved to be good candidates for the detection of these wavelengths. Besides excellent basic characteristics, the resonance between spin-orbit coupling and bandgap values makes this material exceptionally attractive for the manufacture of low noise avalanche photodiodes. Recent metallurgical progress has enabled us to grow high quality ingots up to 40 mm diameter using the Travelling Heater Method with a homogeneity better than 0.2% for x values around 0.7. A highly reproducible planar technology has been developed to manufacture high sensitivity (0.8 A/W)n + -n-p photodiodes with an active area up to 5 mm diameter and a very low reverse current. The high hole-to-electron multiplication coefficient ratio leads to high gain avalanche photodiodes with an excess noise factor lower than 0.5. These CMT components are currently being manufactured on an industrial basis for optical receiver equipments and for laser feedback photodiodes now in field use.

Avalanche Photodiodes with Enhanced Ionization Rates Ratio: Towards a Solid State Photomultiplier

Recent results on a new class of low excess noise avalanche photodiodes (APDs) are discussed. A significant enhancement of the ionization rates ratio has been demonstrated in AlGaAs/GaAs superlattice and graded gap APDs. In addition two novel APDs where only electrons ionize (channeling and staircase APDs) have been disclosed. The staircase APD has lower bias voltage (5-10V) than conventional APDs and virtually noise free multiplication similarly to a phototube.

Channeling photodiode: A new versatile interdigitated p-n junction photodetector

We report on the operation of the first channeling photodetector. This device can be operated as an ultrahigh sensitivity photocapacitive detector; large capacitance variations (≂1 pF) have been induced by very low power levels (≂20 pW). In addition this structure may be used as a low punch through voltage pin photodiode with an ultralow capacitance (≂0.06 pF) largely independent of the detector area and of the doping level of the layers. Finally this device represents the first step towards the implementation of the recently disclosed low noise avalanche photodiode with separated electron and hole avalanche regions.