Low Multiplication Noise Research Articles

Electron-initiated low noise 1064 nm InGaAsP/InAlAs avalanche photodetectors.

We report an electron-initiated 1064 nm InGaAsP avalanche photodetectors (APDs) with an InAlAs multiplier. By utilizing a tailored digital alloy superlattice grading structure, a charge layer and a p type InAlAs multiplier, an unity gain quantum efficiency of 48%, a low room temperature dark current of 470 pA at 90% breakdown voltage, and a low multiplication noise with an effective k ratio of ∼0.2 are achieved. The measured maximum gain factor is 5 at room temperature, which is currently limited by the non-optimized electric field profiles, and can be readily enhanced by modifying the doping and thickness parameters for the multiplier and the charge layer.

Influence of δ p-doping on the behaviour of GaAs/AlGaAs SAM-APDs for synchrotron radiation

This work focuses on the development and the characterization of avalanche photodiodes with separated absorption and multiplication regions grown by molecular beam epitaxy. The i-GaAs absorption region is separated from the multiplication region by a δ p-doped layer of carbon atoms, which ensures that after applying a reverse bias, the vast majority of the potential drops in the multiplication region. Therein, thin layers of AlGaAs and GaAs alternate periodically in a so-called staircase structure to create a periodic modulation of the band gap, which under bias enables a well-defined charge multiplication and results in a low multiplication noise. The influence of the concentration of carbon atoms in the δ p-doped layer on the device characteristics was investigated and experimental data are presented together with simulation results.

AlInAsSb/GaSb staircase avalanche photodiode

Over 30 years ago, Capasso and co-workers [IEEE Trans. Electron Devices 30, 381 (1982)] proposed the staircase avalanche photodetector (APD) as a solid-state analog of the photomultiplier tube. In this structure, electron multiplication occurs deterministically at steps in the conduction band profile, which function as the dynodes of a photomultiplier tube, leading to low excess multiplication noise. Unlike traditional APDs, the origin of staircase gain is band engineering rather than large applied electric fields. Unfortunately, the materials available at the time, principally AlxGa1−xAs/GaAs, did not offer sufficiently large conduction band offsets and energy separations between the direct and indirect valleys to realize the full potential of the staircase gain mechanism. Here, we report a true staircase APD operation using alloys of a rather underexplored material, AlxIn1−xAsySb1−y, lattice-matched to GaSb. Single step “staircase” devices exhibited a constant gain of ∼2×, over a broad range of applied bias, operating temperature, and excitation wavelengths/intensities, consistent with Monte Carlo calculations.

1.31 μm GaAsSb resonant-cavity-enhanced separate absorption, charge and multiplication avalanche photodiodes with low noise

A GaAsSb resonant-cavity-enhanced avalanche photodiode with separate absorption, charge, and multiplication regions has been demonstrated. The peak external quantum efficiency was 36% for device with two pairs of λ/4 MgF2/ZnSe layers as the dielectric top mirror and the full width at half maximum was 7 nm. The breakdown occurred at 24 V and a gain up to 40 was obtained. At 90% of the breakdown, the dark current was 5 nA. The device also exhibited very low multiplication noise and keff was approximately 0.1.

GaAsSb: a novel material for near infrared photodetectors on GaAs substrates

We have studied the molecular beam epitaxy (MBE) growth of GaAsSb on GaAs substrates. The optical properties and composition of GaAsSb layer strongly depend on the growth temperature, the Ga growth rate, and the As and Sb fluxes and their ratios. We also report on two GaAsSb-GaAs photodiode structures operating at 1.3 /spl mu/m. The peak quantum efficiency was 54% for the GaAsSb resonant-cavity-enhanced (RCE) p-i-n photodiode and 36% for the RCE GaAsSb avalanche photodiode (APD) with separate absorption, charge, and multiplication regions (SACM). At 90% of the breakdown, the dark current of the SACM APD was 5 nA. The GaAsSb SACM APD also exhibited very low multiplication noise and k/sub eff/ was approximately 0.1, which is the lowest ever reported for APDs operating at 1.3 /spl mu/m.

Multiplication noise of AlxGa1−xAs avalanche photodiodes with high Al concentration and thin multiplication region

We report that homojunction AlxGa1−xAs avalanche photodiodes (APDs) exhibit very low multiplication noise when the Al content is ⩾80%. It was also found that, due to nonlocal effects, the multiplication noise decreased as the ionization region thickness was reduced from 0.8 μm to ⩽0.2 μm for Al ratios (from 0 to 0.9). The excess noise factor of the thin (140 nm) Al0.9Ga0.1As APDs is the lowest reported to date for III–V compounds and is comparable to that of Si avalanche photodiodes.

Quantum-dot resonant-cavity separate absorption, charge, and multiplication avalanche photodiode operating at 1.06 μm

We report on the design, fabrication and performance of a quantum-dot (QD) resonant-cavity separate absorption, charge, and multiplication avalanche photodiode (APD). The device was grown on GaAs using molecular beam epitaxy and was designed to detect light near 1.06 μm. The absorbing region consists of a stack of five self-assembled QD layers, that were formed by the deposition of six monolayers of In/sub 0.5/Ga/sub 0.5/As, with GaAs spacer layers. The peak efficiency at 1.06 μm is 57% with a spectral bandwidth of 1.3 nm. The photodiode exhibits low dark current, low multiplication noise (k<0.3), good gain characteristics and a low-breakdown voltage (/spl sim/15 V), which is much lower than that of Si-based APD's operating at 1.06 μm.

High-speed resonant-cavity separate absorption and multiplication avalanche photodiodes with 130 GHz gain-bandwidth product

Previously it has been shown that resonant-cavity, separate absorption and multiplication (SAM) avalanche photodiodes (APDs) exhibit high peak external quantum efficiency (∼75%), low dark current, low bias voltage (&amp;lt;15 V), and low multiplication noise (0.2&amp;lt;k&amp;lt;0.3). We describe the frequency response of resonant-cavity AlGaAs/GaAs/InGaAs SAM APDs. A unity-gain bandwidth of 23 GHz and a high gain-bandwidth product of 130 GHz have been achieved.

High-speed distributed feedback laser and InGaAs avalanche photodiodes

Optical semiconductor devices, including InGaAsP/InP distributed feedback lasers and InGaAs avalanche photodiodes, are required for high-bit-rate transmission systems. In distributed-feedback lasers, it is important to increase the 3-dB bandwidth, to reduce the frequency chirping, and to stabilize the longitudinal mode under large signal modulation. For avalanche photodiodes, high gain-bandwidth product, low multiplication noise, low multiplied dark current, and low capacitance are key factors. How to realize these characteristics is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The p-n junction quantum well APD: A new solid-state photodetector for lightwave communications systems and on-chip detector applications

A novel variation on the doped quantum well avalanche photodiode is presented that provides comparable signal-to-noise performance at more realizable material doping requirements. The device consists of repeated unit cells formed from a p-n Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</inf> As junction immediately followed by near-intrinsic Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</inf> As and Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</inf> As layers. As in the doped quantum well device, the asymmetric unit cell selectively heats the electron distribution much more than the hole distribution prior to injection into the narrow-gap Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</inf> As layer in which impact ionization readily occurs. The effects of various device parameters, such as the junction doping, Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</inf> As and intrinsic Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</inf> In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</inf> As layer widths as well as the overall bias on the electron and hole ionization rates, is analyzed using an ensemble Monte Carlo method. From the determination of the ionization rates and the ionization probabilities per stage, P and Q, an optimal device design can be obtained that provides high gain at low multiplication noise. In addition, a structure that operates at less than 5 V bias is presented that can provide moderate gain at very low noise. It is expected that the device designs presented herein can serve either as high-gain low-noise detectors for lightwave communications systems or as moderate-gain low-noise detectors for on-chip application.

A low-noise n+np germanium avalanche photodiode

A low-noise n+np germanium avalanche photodiode which successfully operates in the wavelength region of 0.8-1.5 \mu m has been designed, fabricated, and tested. Low-excess noise factor F \sim 7 is experimentally obtained at a multiplication factor of M \sim 10 and at a wavelength \lambda \sim 1.3 \mu m, whereas the calculated one is 7.6. Quantum efficiency is as high as 80 percent and a cutoff frequency (-3 dB) is 500 MHz at M \sim 10 and \lambda \sim 1.3 \mu m. Overall performance of an n+np Ge-APD fabricated is estimated at \lambda = 1.3 \mu m, and compared with that of a III-V alloy APD (InGaAs-InP) by calculating minimum detectable power. An n+np Ge-APD has shown minimum detectable power only 1.7 dB larger than that of a III-V APD at a signal-to-noise ratio of 22 dB and at a bandwidth of 100 MHz. An n+np Ge-APD also shows low-multiplication noise and considerably low minimum detectable power in the 0.8 μm region. Breakdown voltage of an n+np Ge-APD is 31 V and is much lower than that of a Si-APD. The n+np Ge-APD is found to be a useful detector in the whole wavelength region 0.8-1.5 \mu m of optical communication systems.

New InGaAs/InP avalanche photodiode structure for the 1-1.6 &amp;#181;m wavelength region

Low dark current and low multiplication noise properties for an In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</inf> As/InP avalanche photodiode are described. The diode is prepared with an In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</inf> As light absorption layer and an InP avalanche multiplication region. The lowest dark current density of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5.2 \times 10^{-4}</tex> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is obtained at 90 percent of a breakdown voltage. Multiplication noise power is proportional to the 2.7th power of the current multiplication factor. Impact ionization coefficient by holes is larger by 2-3 times than that by electrons in

Design and Characteristics of Low Noise and High Speed Silicon Avalanche Photodiodes

Multiplication noise and depletion layer width of silicon avalanche photodiodes are calculated for several impurity density profiles adjacent to the junction. From calculated results on these models of impurity density profile, a low-high-low structure is shown to be superior in obtaining a low multiplication noise property and wide depletion layer width at a given breakdown voltage. Experimental multiplication noise on a diode with low-high-low structure with 100 V breakdown voltage is k=0.03–0.04, where k is ionization coefficient ratio. Pulse response is improved by incorporating an impurity gradient deep in the light absorption region. The gain-bandwidth product is 150 GHz at the multiplication factor of 100.

Silicon avalanche photodiodes with low multiplication noise and high-speed response

Low-noise and high-speed silicon avalanche photodiodes with low breakdown voltage are reported. The diode structure with a low-high-low impurity density profile is proposed to have low-noise characteristics. Multiplication noise and depletion layer width of several structures are compared theoretically, and effects of impurity density profile of the avalanche region are discussed. Built-in field is also provided to realize high-speed response without increasing operating voltage. Silicon avalanche photodiodes with the above mentioned structure have been fabricated with long time substrate annealing, ion implantation, and epitaxial growth. Attained performances are as follows: noise parameter k = 0.027 - 0.040, output pulse half width τ = 260 ps for a mode-locked Nd:YAG laser pulse, gain-bandwidth product up to 300 GHz at M = 400, quantum efficiency 0.55 - 0.66 at the 0.81- to 0.83-µm wavelength, and breakdown voltage about 100 V.