Quantum Efficiency Of Photodiodes Research Articles

Determination of Quantum Efficiency in In<inline-formula><tex-math>$_{\bf {0.53}}$</tex-math> </inline-formula>Ga<inline-formula><tex-math>$_{\bf{0.47}}$</tex-math></inline-formula>As-InP-Based APDs

A method to precisely determine the quantum efficiency and primary photocurrent in avalanche photodiodes (APDs) is presented based on a linear relationship between excess noise factor F and gain, M. The new method is used to accurately compare performance of modern APD designs when nonlocal impact ionization effects govern the relationship between noise and gain.

Carrier transport properties of Be-doped InAs/InAsSb type-II infrared superlattices

The InAs/InAsSb type-II superlattice materials studied to date for infrared detector applications have been residually n-type, but p-type absorber regions with minority carrier electrons can result in increased photodiode quantum efficiency, RoA, and detectivity. Therefore, Be-doped InAs/InAsSb superlattices were investigated to determine the p-type InAs/InAsSb superlattice material transport properties essential to developing high quality photodiode absorber materials. Hall measurements performed at 10 K revealed that the superlattice converted to p-type with Be-doping of 3 × 1016 cm−3 and the hole mobility reached 24 400 cm2/Vs. Photoresponse measurements at 10 K confirmed the 175 meV bandgap and material optical quality.

A Theoretical and Experimental Determination of the Internal Quantum Efficiency of Silicon Photodiodes

A new method of processing the experimental current-voltage characteristics of photodiodes using reference points is proposed. By comparing a trap detector, developed at the All-Russia Research Institute of Optophysical Measurements based on Hamamatsu S6337 photodiodes with an HH-03-1337 trap detector, certified using a cryogenic radiometer at the PTB, an experimental value of the internal quantum efficiency of the Hamamatsu S6337 photodiode is obtained.

Photodiodes based on InAs/InAsSb/InAsSbP heterostructures with quantum efficiency increased by changing directions of reflected light fluxes

It is shown, using the example of InAs/InAsSb/InAsSbP heterostructures, that the formation of a curvilinear reflecting surface consisting of hemispherical etch pits on the rear side of a photodiode chip leads to an increase in the quantum efficiency of photodiodes by a factor of 1.5–1.7 in the entire mid-IR wave-length interval studied (λ = 3–5 μm). For the obtained photodiodes with a cutoff wavelength of 4.8 μm, a photosensitive area of 0.1 mm2, and a chip area of 0.9 mm2, a monochromatic responsivity at λ = 4.0 μm reached 0.6 A/W, while a dark current at a reverse bias voltage of 0.2 V was within 4–6 A/cm2.

Quantum-efficiency enhancement of CMOS photodiodes by deliberate violation of design rules

In this paper we propose and experimentally prove that the quantum efficiency of CMOS-compatible photodiodes can be improved in any standard process at no additional complexity, cost or surface area. The improvement is obtained by slightly boosting the drift component with respect to the diffusion component of the photogenerated current by means of an increase in the p–n junction effective area, and consequently in the volume of the depletion layer. This is accomplished by texturing the junction profile, which is realized when we intentionally violate the design rules that dictate the minimum distance between supposedly independent diffusion or implanted regions, and when we use the gate-oxide mask accordingly. To form a composite photodiode these closer bordering regions partially merge due to lateral diffusion that expand further under the boundaries of the respective photomask definitions throughout the overall thermal cycle in the process. Several characteristics of different process generations are discussed. We achieved 4% measured efficiency gain in an n-well/p-epi textured structure compared to a p+/n-well/p-epi conventionally flat photodiode. A quantum efficiency gain of at least 18% can be inferred, from an artifactual test, between textured and flat n-well/p-epi junctions.

Fabrication and Study Zinc Sulfide Schottky Barrier Detectors

Schottky barrier photodiode of zinc sulfide (ZnS) thin film have been fabricated by thermal evaporation method. The ntype ZnS thin films of thickness 400 nm were deposited onto glass substrates at 150°C. The photodiode was form by evaporation of gold thin films on the n-type ZnS films and evaluated as UV near visible detectors. ZnS thin films were checked by using X-ray diffraction (XRD); the result shows that the films were polycrystalline. The lattice constant for ZnS films was calculated and it was 5.41A°. The absolute quantum efficiency of the photodiode was measured for wavelengths between 200-600 nm. The responsivety of the prepared photodiodes of different thickness of gold thin films (50, 80&100 nm) was measured for wavelengths at the range as mentioned above. These detectors have negligible response to wavelengths longer than 340 nm which correspond to energies less than the band gap of the zinc sulfide. Finally the barrier height of diode was measured by the C-V method and found as low as 1.9 V.

Effect of strain on quantum efficiency of InAlN-based solar-blind photodiodes

A series of InxAl1−xN-based Schottky solar-blind photodiodes are fabricated on the InxAl1−xN epilayers with high and very close crystal qualities. The quantum efficiency varies from 14.5% to 68.5%. The microstructure and strain state of epilayers are investigated in detail. It is found that the quantum efficiency of photodiode depends on the strain state in InxAl1−xN films. This indicates that adjusting the strain state in InxAl1−xN film is one of the promising approaches to optimize the performance of InAlN-based solar-blind photodiode.

Optical matching layer structures in evanescent coupling photodiodes at a wavelength of 1.55 μm: physics, design and simulation

We have studied the optical matching layers (OMLs) and external quantum efficiency in the evanescent coupling photodiodes (ECPDs) integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-vectorial beam propagation method (BPM). The physical basis of OML has been identified, thereby a general designing rule of OML is developed in such a kind of photodiode. In addition, the external quantum efficiency and the polarization sensitivity versus the absorption and coupling length are analysed. With an optical matching layer, the absorption medium with a length of 30 μm could absorb 90% of the incident light at 1.55 μm wavelength, thus the total absorption increases more than 7 times over that of the photodiode without any optical matching layer.

Modeling the imaging performance of prototype organic x‐ray imagers

A unified Monte Carlo and cascaded systems model for the simulation of active-matrix flat-panel imagers is presented. With few input parameters, the model simulated the imaging performance of previously measured flat-panel imagers with reasonable accuracy. The model is used to predict the properties of conceptual flat-panel imagers based on organic semiconductors on plastic substrates. The model suggests that significant improvements in resolution and detective quantum efficiency could be achieved by operating such a detector in a back-side illuminated configuration, or by employing two imaging arrays arranged face-to-face. The effect of semiconductor properties on the conceptual imagers is investigated. According to the model, a photodiode quantum efficiency of 25% and dark current of less than 100 pA mm(-2) would be satisfactory for a prototype imager, while a competitive imager would require a photodiode quantum efficiency of 40-50% with a dark current of less than 10 pA mm(-2) to be quantum limited over the radiographic exposure range.

Extended One-Dimensional Analysis to Effectively Derive Quantum Efficiency of Various CMOS Photodiodes

This paper proposes an extended 1-D analysis to derive quantum efficiency of various commonly used CMOS photodiodes. The theoretical model of the CMOS photodiode with the n-/p-epitaxial/p + substrate (n-/p-epi/p + sub) structure is established from steady-state continuity equations, where most existing boundary conditions are applied. In particular, the minority carrier and current densities are continuous across the interface between two layers with the same dopant type. Models of the other commonly used CMOS photodiodes are also examined. Three CMOS photodiodes with n-/p-substrate (n-/p-sub), p+/n-/p-substrate (p+/n-/p-sub), and n-/p-epi/p + sub structures are fabricated and characterized to validate the proposed model. Additionally, the surface recombination velocity is adequately determined by fitting the simulated quantum efficiency to the measured value. The simulated quantum efficiency of the proposed model for these three photodiodes is quite consistent with the measured values, revealing the feasibility and effectiveness of the proposed model in characterizing various CMOS photodiodes.

Characterization of quantum efficiency, effective lifetime and mobility in thin film ungated SOI lateral PIN photodiodes

This paper presents an analytical model of the optical sensitivity and dark current of thin film SOI PIN diodes validated by measurements. This allows us to prove the very good adequacy of thin film SOI for UV-sensing (quantum efficiency in excess of 60% without any anti-reflection coating and dark current lower than pA for a total diode area of 50 × 50 μm 2) and to propose a new method for extracting the effective lifetime and electron, and hole mobilities in SOI thin film ungated structures.

An avalanche photodiode photon counting camera for high-resolution astronomy

A system is described which makes best use of the high quantum efficiency and high count rate capability of avalanche photodiodes for high time resolution observations of optical pulsars. The use of three APDs allows simultaneous photometry of the target and a reference star, and the monitoring of the sky background. By minimising the optical components in the light path the optical efficiency of the system is maximised. The TRIFFID (Shearer, A., Stappers, B., O'Connor, P., Golden, A., Strom, R., Redfern, M., Ryan, O.: Science 301, 493–495 (2003)) and OPTIMA (Straubmeier, C., Kanbach, G., Schrey, F.: Exp. Astron. 11, 157–170 (2001)) have shown that fibre-fed APD arrays can produce excellent results. This, new, system was used on the 6m BTA in November 2003 – results on the Crab pulsar are presented.

Detection Efficiencies and Generalized Breakdown Probabilities for Nanosecond-Gated Near Infrared Single-Photon Avalanche Photodiodes

A rigorous model is developed for determining single-photon quantum efficiency (SPQE) of single-photon avalanche photodiodes (SPADs) with simple or heterojunction multiplication regions. The analysis assumes nanosecond gated-mode operation of the SPADs and that band-to-band tunneling of carriers is the dominant source of dark current in the multiplication region. The model is then utilized to optimize the SPQE as a function of the applied voltage, for a given operating temperature and multiplication-region structure and material. The model can be applied to SPADs with In/sub 0.52/Al/sub 0.48/As or InP multiplication regions as well as In/sub 0.52/Al/sub 0.48/As--InP heterojunction multiplication regions for wavelengths of 1.3 and 1.55 /spl mu/m. The predictions show that the SPQE generally decreases with decreasing the multiplication-region thickness. Moreover, an InP multiplication region requires a lower breakdown electric field (and, hence, offers a higher SPQE) than that required by an In/sub 0.52/Al/sub 0.48/As layer of the same width. The model also shows that the fractional width of the In/sub 0.52/Al/sub 0.48/As layer in an In/sub 0.52/Al/sub 0.48/As--InP heterojunction multiplication region can be optimized to attain a maximum SPQE that is greater than that offered by an InP multiplication region. This effect becomes more pronounced in thin multiplication regions as a result of the increased significance of dead space.

New model for the internal quantum efficiency of photodiodes based on photocurrent analysis

A new expression for the internal quantum efficiency of a photodiode is presented. It is obtained from the analysis of the photocurrent generated within the diode, considering the power and the cross-sectional diameter of the incident beam. The model explains variations of the internal quantum efficiency with irradiance that are not explained by other existing models, although this experimental fact was already known. The well-known phenomenon of supraresponsivity is also explained with this model. Finally, we show the dependence of the internal quantum efficiency on the variables involved in the model.

Ge∕Si Photodiodes and Phototransistors with Embedded Arrays of Germanium Quantum Dots for Fiber-Optic Communication Lines

Photodetectors based on Ge/Si multilayer heterostructures with germanium quantum dots are fabricated for use in fiber-optic communication lines operating in the wavelength range 1.30–1.55 μm. These photodetectors can be embedded in an array of photonic circuit elements on a single silicon chip. The sheet density of germanium quantum dots falls in the range from 0.3 × 1012 to 1.0 × 1012 cm−2, and their lateral size is approximately equal to 10 nm. The heterostructures are grown by molecular-beam epitaxy. For a reverse bias of 1 V, the dark current density reaches 2 × 10−5 A/cm2. This value is the lowest in the data on dark current densities available in the literature for Ge/Si photodetectors at room temperature. The quantum efficiency of photodiodes and phototransistors subjected to illumination from the side of the plane of the p-n junctions is found to be 3% at a wavelength of 1.3 μm. It is demonstrated that the maximum quantum efficiency is achieved for edge-illuminated waveguide structures and can be as high as 21 and 16% at wavelengths of 1.3 and 1.5 μm, respectively.

A Comparison of Lattice-Matched GaInNAs and Metamorphic InGaAs Photodetector Devices

AbstractThe dilute-nitride GaInNAs shows great promise in becoming the next choice for 1 eV photodetector and multi-junction photovoltaic applications due to the ability for it to be grown lattice-matched on GaAs substrates. This paper will present results from high-power photodetector devices fabricated from high-quality thick GaInNAs and metamorphic InGaAs materials grown by MBE. The internal quantum efficiency of rear-illuminated PIN photodiodes with thick GaInNAs films as the intrinsic region (roughly 62% at 1064 nm) is somewhat lower than comparable metamorphic InGaAs devices (roughly 75% at 1064 nm). However, the dark current density of the GaInNAs devices is also somewhat lower (roughly 3 μA/cm2 at 2×104 V/cm bias) than the InGaAs devices (roughly 20 μA/cm2 at 2×104 V/cm bias), while the breakdown voltages (beyond -20 V) are comparable. Materials characterization of each structure, including x-ray diffraction and room-temperature as well as temperature-dependent photoluminescence studies will be presented in order to explain the characteristics observed in the devices composed of the two different material systems.

BGO readout with photodiodes as a soft gamma-ray detector at [formula omitted

BGO is expected to be plausible devices for soft gamma-ray detectors, because of a high detection efficiency for soft gamma-rays. Here we report on the good performance of BGO readout with PIN—photodiode or avalanche photodiode as a soft gamma-ray detector. We confirmed that the signal output of BGO becomes comparable to that of GSO when it is readout with photodiodes due to better matching between emission wavelength of BGO and quantum efficiency of photodiode. The energy resolution of 6.2% and 3.4% for 662 and 1836 keV, respectively, gamma-rays at - 30 ∘ C is obtained with the combination of the 5 × 5 × 5 mm 3 cube BGO and the Hamamatsu avalanche photodiode (APD) S8664-55. In this combination, the lowest detectable energy is found to be ∼ 10 keV . These performances are better than that obtained with Photomultiplier tube (PMT), and our results increase many possible applications of BGO readout with photodiodes as soft gamma-ray detectors.

Detector efficiency limits on quantum improvement

Although the National Institute of Standards and Technology has measured the intrinsic quantum efficiency of Si and InGaAs avalanche photo diode (APD) materials to be above 98% by building an efficient compound detector, commercially available devices have efficiencies ranging between 15 and 75%. This means bandwidth, dark current, cost, and other factors are more important than quantum efficiency for existing applications. For non-classical correlated photon applications, the system's correlated signal-to-noise ratio is proportional to (ηN)½ /(1 − η)½, rather than the classical signal-to-noise (ηN)½. Consequently, the detector design trade space must be re-evaluated. This paper systematically examines the generic detection process, lays out the considerations needed for designing detectors for non-classical applications, and identifies the ultimate physical limits on quantum efficiency.

Dark count probability and quantum efficiency of avalanche photodiodes for single-photon detection

We propose a physical model that quantitatively describes the behavior of the dark count probability and single-photon quantum efficiency of avalanche diodes under conditions that allow these devices to be used for single-photon detection. The model shows analytically how various physical parameters such as dark current, dc gain, Geiger mode gain, carrier detrap time, pulse repetition rate, etc., can affect the dark count probability and single-photon quantum efficiency of a Geiger mode avalanche photodiode. The theory agrees well with the experimental results.

Quantum efficiency of silicon photodiodes in the near-infrared spectral range.

The quantum efficiency of silicon photodiodes and factors that might be responsible for the drop in quantum efficiency in the near-infrared spectral range were analyzed. It was shown that poor reflectivity from the rear surface of the die could account for a decrease in Si photodiode quantum efficiency in near-infrared spectral range by more than 20%. The photodiode quantum efficiency was modeled with an appropriate representation for the carrier-collection efficiency dependence on the die penetration depth. A corrected analytical expression for calculating the photodiode quantum efficiency is given. Some methods to improve the quantum efficiency of silicon photodiodes in near-infrared spectral range are discussed.