Si Photodiode Research Articles

A butterfly shape acceptor with rigid skeleton and unique assembly enables both efficient organic photovoltaics and high-speed organic photodetectors

Abstract It remains challenging to design efficient bifunctional semiconductor materials in organic photovoltaic and photodetector devices. Here, we report a butterfly-shaped molecule, named WD-6, which exhibits low energy disorder and small reorganization energy due to its enhanced molecular rigidity and unique assembly with strong intermolecular interaction. The binary photovoltaic device based on PM6:WD-6 achieved an efficiency of 18.41%. Notably, an efficiency of 19.42% was achieved for the ternary device based PM6:BTP-eC9:WD-6. Moreover, the photodetection device based on WD-6 demonstrated an ultrafast response speed (205 ns response time at λ of 820 nm) and a high cutoff frequency of -3 dB (2.45 MHz), surpassing the values of most commercial Si photodiodes. Based on these findings, we show-cased an application of the WD-6-based photodetection device in high-speed optical communication. These results offer valuable insights into the design of organic semiconductor materials capable of simultaneously exhibiting high photovoltaic and photo detective performance.

Direct characterisation of AM-to-PM phenomena in fast Si and InGaAs photodiodes

The direct measurement method of AM-to-PM phenomena in fast silicon and InGaAs photodiodes is described. The setup is simple, relatively inexpensive and allows fast and precise measurements not only in a laboratory environment. During sample tests, the authors have found that the influence of bias voltage on the phase shift of an optical signal conversion is significant. The reported effect together with the influence of modulation depth on phase shift (AM-to-PM conversion) has a negative impact on an optical signal reception especially in coherent applications. The authors show that, with our proposed setups, it is possible to find optimal bias voltage and optimal optical power in order to reduce electrical phase noise of the photodetector.

Hybrid trap detector sensitive at visible and telecom wavelengths

Abstract We have developed a transmission trap detector sensitive over a wide optical wavelength range. The developed device takes advantage of the smooth reflectance profile of silicon photodiodes. The detector is based on two 10 mm size photodiodes – a Si photodiode and an InGaAs photodiode. The constructed hybrid trap detector is sensitive at the wavelength range from 400 nm up to 1600 nm. The detector is designed to provide a tool for countermeasures against attacks to secure quantum communication.

A mosaic-type array composed of Si photodiodes for charged-particle detection

A mosaic-type array composed of Si photodiodes for charged-particle detection

SPECIFICS OF DESIGNING AN INFRARED PYROMETER-REFLECTOMETER FOR SEMICONDUCTOR HETEROSTRUCTURE FABRICATION

There are general technical requirements for all types of reactors for chemical vapour deposition technology using AIII- BV metalorganic compounds. Among them, it is worth highlighting the large temperature gradients that cause the origin of convection loops, which in turn, taking into account the high speed of the gas flow, lead to turbulence in the reactor instead of the expected laminar flow. It is also important to take into account the change in parameters of the wafer surface during the growth process and the need for signal separation between the useful signal from the wafer surface and the background signal from the wafer carrier, which rotates at fixed speed for uniform deposition of compounds. To obtain high-quality heterostructures with reproducible parameters, it is important to have a system of precise temperature control on the wafer surface directly in the deposition area, since the deposition process for many complex semiconductor devices (for example, laser diodes, LEDs, photodiodes, transistors on heterojunctions) is very sensitive to temperature changes. The method of optical pyrometry is a non-contact method that allows to precisely determine the temperature of the wafer surface and meets the technical requirements of CVD epitaxy growth reactors. This article is devoted to the analysis of the features of the development of optoelectronic systems for precise temperature measurement during epitaxial growth in order to determine the criteria for the selection or development of components of the optoelectronic system of the pyrometer-reflectometer. The main physical processes, electro-optical characteristics of Si photodiode, AlGaAs/GaAs LED and parameters of bandpass interference filters were investigated. Based on the analysis of the obtained research and measurement results, scientific recommendations have been developed. The recommendations aimed at the selection and optimization of the parameters of the components of the pyrometer-reflectometer (photodetectors, light emitting diodes, optical filters) in order to improve the accuracy and temperature stability of measurements in the pyrometer’s operation conditions, which take into account the compensation of emissivity change from the surface of the wafer.

Flexoelectric Engineering of Bulk Photovoltaic Photodetector.

The bulk photovoltaic effect (BPVE) offers an interesting approach to generate a steady photocurrent in a single-phase material under homogeneous illumination, and it has been extensively investigated in ferroelectrics exhibiting spontaneous polarization that breaks inversion symmetry. Flexoelectricity breaks inversion symmetry via a strain gradient in the otherwise nonpolar materials, enabling manipulation of ferroelectric order without an electric field. Combining these two effects, we demonstrate active mechanical control of BPVE in suspended 2-dimensional CuInP2S6 (CIPS) that is ferroelectric yet sensitive to electric field, which enables practical photodetection with an order of magnitude enhancement in performance. The suspended CIPS exhibits a 20-fold increase in photocurrent, which can be continuously modulated by either mechanical force or light polarization. The flexoelectrically engineered photodetection device, activated by air pressure and without any optimization, possesses a responsivity of 2.45 × 10-2 A/W and a detectivity of 1.73 × 1011 jones, which are superior to those of ferroelectric-based photodetection and comparable to those of the commercial Si photodiode.

Large optoelectronic chromatic dispersion in PN-type silicon photodiodes and photovoltaic cells.

Optoelectronic chromatic dispersion (OED) is a significant source of effective chromatic dispersion in photodiodes. We present an experimental and theoretical study of OED in PN-type Si photodiodes and photovoltaic cells and report on a very large effective chromatic dispersion in these devices. As measured with the modulation phase-shift technique at a frequency of 4 kHz for these slow devices, the OED spectral sensitivity for a commercial Si photodiode is approx. 0.02 deg/nm in the 720-850 nm wavelength band and increases to 0.25 deg/nm at λ = 1µm. For a Si photovoltaic cell, the OED is approx. 0.09 deg/nm in this spectral region. These values translate into an effective chromatic dispersion parameter of approx. 1012ps/(n m ×k m) for these sub-millimeter device lengths, which is over eight orders of magnitude larger than high-dispersion materials such as chalcogenide glass. The enormous dispersion in these sub-millimeter sized silicon-based devices can be utilized for on-chip optoelectronic sensors such as wavelength monitoring and spectroscopy. The substantial OED of photovoltaic cells can be utilized for the characterization and optimization and new applications for optical sensing with these self-powered devices.

Effect of Surface Structure on the Sensitivity of Fluorescence-Enhanced Si Photodiodes for Ultraviolet C Light Measurement

This study aims to significantly enhance the sensitivity of a fluorescence-enhanced Si photodiode (FE-PD) to ultraviolet C-ray (UVC) light by optimizing the three-dimensional surface shape of the phosphor attached to the Si-PD, thereby increasing the UVC detection sensitivity. In the sensitivity-enhanced FE-PD, the surface of the red fluorescent acrylic resin phosphor affixed to the Si-PD was carved with a stripe and grid at varying depths, and triangular roofs and square pyramids at various angles. The effects of roughening the phosphor surfaces with diamond abrasives of varying mesh sizes—ranging from #180 to #3000—were comparatively evaluated against those with flat, mirror-like surfaces. As observed, the UVC light sensitivity of the FE-PD using a surface-carved triangular roofs and square pyramids at angle of 70° exhibited significant improvements compared to the Si-PD with both non-modified and mirror-polished phosphors. Thus, the FE-PD with a surface-modified phosphor is a promising candidate for UVC light sensor.

Development of a mosaic-type array formed by Si photodiodes for charged-particle detection in heavy-ion collisions

Silicon (Si) detectors find widespread application in heavy-ion collisions. In order to achieve a position-sensitive charged-particle detection with a relatively low cost, we have developed a mosaic-type array based on off-the-shelf Si photodiodes (Hamamatsu S13955-01). Its high modularity allows one to modify the geometric configuration of the array according to specific experimental requirements. In this contribution, characteristics of the photodiode tested with α source and experimental results of the α-decay spectroscopy are presented.

Enhanced efficiency of high-speed Si and Si-based PbSe MSM photodiodes with integrated photon-trapping holes at 800–1550 nm wavelengths

Enhanced efficiency of high-speed Si and Si-based PbSe MSM photodiodes with integrated photon-trapping holes at 800–1550 nm wavelengths

New Crystal Photodiode Combination for Environmental Radiation Measurement

Here, a new design will be introduced to detect radiation in the environment with high efficiency. The designed structure consists of placing ZnS–Si APD and PIN photodiodes at the ends of conventional crystals such as NaI(Tl) and CsI(Tl). Since ZnS is transparent to photons with wavelengths between 340 and 10000 nm, photons coming from the crystals are absorbed directly in the depletion region and generate primary particles. With an increase in the number of generated primary particles, a stronger and cleaner signal is obtained. In the simulation work, the light generated by 30 keV–3 MeV gamma rays in the crystals was obtained using the Geant4 simulation code. The single-particle Monte Carlo technique was used to calculate the photodiode output signal for the crystal emission spectrum. The simulation results showed that the crystals and ZnS–Si photodiode structures formed a good combination. The high quantum efficiency and low excess noise factor make the ZnS–Si structure an excellent choice for scintillating light detection.

High-speed flexible near-infrared organic photodiode for optical communication.

Optical communication is a particularly compelling technology for tackling the speed and capacity bottlenecks in data communication in modern society. Currently, the silicon photodetector plays a dominant role in high-speed optical communication across the visible-near-infrared spectrum. However, its intrinsic rigid structure, high working bias and low responsivity essentially limit its application in next-generation flexible optoelectronic devices. Herein, we report a narrow-bandgap non-fullerene acceptor (NFA) with a remarkable π-extension in the direction of both central and end units (CH17) with respect to the Y6 series, which demonstrates a more effective and compact 3D molecular packing, leading to lower trap states and energetic disorders in the photoactive film. Consequently, the optimized solution-processed organic photodetector (OPD) with CH17 exhibits a remarkable response time of 91ns (λ = 880nm) due to the high charge mobility and low parasitic capacitance, exceeding the values of most commercial Si photodiodes and all NFA-based OPDs operating in self-powered mode. More significantly, the flexible OPD exhibits negligible performance attenuation (<1%) after bending for 500 cycles, and maintains 96% of its initial performance even after 550h of indoor exposure. Furthermore, the high-speed OPD demonstrates a high data transmission rate of 80MHz with a bit error rate of 3.5 [Formula: see text] 10-4, meaning it has great potential in next-generation high-speed flexible optical communication systems.

Ultra‐High Detectivity MBene/Si vdW Schottky Photodiode for Color Single‐Pixel Imaging

AbstractThe color single‐pixel imaging (SPI) has received significant attention due to its ability to provide more comprehensive real‐world information compared to grayscale imaging. The performance of single‐pixel photodetector is the primary determinant for the quality of color SPI. Silicon‐based Schottky photodiodes provide desirable qualities for the essential requirements of high detectivity in high resolution color SPI. Herein, a novel Mo4/3B2‐XTZ/Si hexagonal micro‐hole array (SiHMA) van der Waals (vdW) Schottky photodiode is first constructed for application in color SPI. The resultant Schottky junction possesses a Schottky barrier height up to 1.18 eV, thus leading to a dark current density of 1.47 × 10−13 A cm−2 and an ultra‐high detectivity of 4.4 × 1014 Jones at zero bias voltage, which are superior to most of Si‐based Schottky photodiodes reported and even some commercial Si photodiodes thus far. Importantly, the high detectivity and low dark current density of the photodiode allow for the use as a photodetector in high resolution Hadamard SPI. Notably, a high‐quality 256 × 256‐pixel color image can be successfully achieved under even 25% sampling rate without an additional filter circuit. This work opens an avenue toward the fabrication of high detectivity Schottky photodiode for high quality color SPI.

Higher harmonics of the intensity modulated Photocurrent/Photovoltage spectroscopy response - a tool for studying photoelectrochemical nonlinearities

In this work, a higher harmonic analysis (HHA) of the intensity modulated photocurrent/photovoltage (IMPS/IMVS) spectroscopy data is proposed as a potent tool for studying nonlinear phenomena in photoelectrochemical and photovoltaic systems. Analytical solutions of kinetic equations were constructed for cases of single and double resonance accounting for various sources of higher harmonics. These sources correspond to the physical sources of nonlinear effects in the response including intensity-dependent generation current, intensity-dependent recombination, and second-order recombination. Due to the fact that the solutions for those cases are different, a qualitative methodology for analysis of harmonics is proposed. The methodology is illustrated by two experimental examples – Si photodiode for IMVS and TiO2 nanotubes for IMPS. It was capable of distinguishing second order recombination in the first case and intensity-dependent transport rate for the latter.

Off-Grid Electrogenerated Chemiluminescence with Customized p-i-n Photodiodes.

Electrochemiluminescence (ECL) is the generation of light induced by an electrochemical reaction, driven by electricity. Here, an all-optical ECL (AO-ECL) system is developped, which triggers ECL by the illumination of electrically autonomous "integrated" photoelectrochemical devices immersed in the electrolyte. Because these systems are made using small and cheap devices, they can be easily prepared and readily used by any laboratories. They are based on commercially available p-i-n Si photodiodes (≈1€unit-1), coupled with well-established ECL-active and catalytic materials, directly coated onto the component leads by simple and fast wet processes. Here, a Pt coating (known for its high activity for reduction reactions) and carbon paint (known for its optimal ECL emission properties) are deposited at cathode and anode leads, respectively. In addition to its optimized light absorption properties, using the commercial p-i-n Si photodiode eliminates the need for a complicated manufacturing process. It is shown that the device can emit AO-ECL by illumination with polychromatic (simulated sunlight) or monochromatic (near IR) light sources to produce visible photons (425nm) that can be easily observed by the naked eye or recorded with a smartphone camera. These low-cost off-grid AO-ECL devices open broad opportunities for remote photodetection and portable bioanalytical tools.

A new prospect to measure the built-in potential for photodiodes

We present a novel approach to determine the built-in potential for photodiodes, which depends on the excitation of the photodiode by a pulsed or modulated light under forward bias. The proposed method was tested for commercially available photodiodes and the measurement results were compared with the values, which were obtained by conventional current–voltage and capacitance–voltage measurements. It was found that the proposed method gave consistent results with current–voltage and capacitance–voltage measurements. For the confirmation of the accuracy of this method, temperature dependent measurements were also performed for Si photodiode in a temperature range of 298−333 K to compare the obtained built-in potential values with theory. This analysis showed that the results of the proposed method were more reliable than the conventional measurements.

Nonlinearity Measurement of Si Transferring Photodetector in the Low Radiation Flux Range

In order to establish a transferring chain from a photon flux of a single-photon source in quantum radiometry, the nonlinearity of the photodetector needs to be accurately measured. Using the flux superposition method, a nonlinearity measurement setup has been designed. The measurement setup consists of two tungsten halogen lamps, parent–child integrating spheres, an adjustable aperture, a diaphragm tube, and an optical filter. It has the advantage of low polarization error, low interference error, and low stray light effect. The Si photodiode to be measured is cooled to −40 °C to obtain a low noise level for low-flux radiation measurement. The nonlinearity of the Si photodetector is measured for photocurrent ranges from 10−12 A~10−6 A level, with a relative standard uncertainty from 0.0092~0.023%. The relative standard uncertainty of the nonlinearity correction factor ranged from 0.023~0.049%.

Designing Ordered Organic Small-Molecule Domains for Ultraviolet Detection and Micrometer-Sized Flexible Imaging.

Photodetectors displaying an ultraviolet (UV) spectral response window are typically based on wide-bandgap semiconductors that have long been dominated by inorganic materials that suffer from bottlenecks of low flexibility and a limited material family. Here, we synthesized a novel organic small molecule and controlled its crystallization to suppress leakage currents and facilitate separation of the carriers, and the relationship between the nanoscale phase separation morphology and the optoelectrical performance of the photodetectors is disclosed. Our optimized organic photodetector (OPD) presents a UV spectral response window, with superior self-powered responsivities of 45 mA/W (under 250 nm light) and 70 mA/W (under 300 nm light), outperforming the Si photodiode and rivaling other reported UV self-powered photodetectors. Finally, an imaging system was constructed to demonstrate the application potential of the OPD in UV flexible imaging with high-resolution arrays of 400 pixels × 400 pixels (5 μm × 5 μm per pixel), which could work in bent states and successfully output images of micrometer-sized objects.

Probing the tunable optical properties of highly luminescent functionalized graphene quantum dots as downconverters for superior detection of ultraviolet radiation

Detection and utilization of ultraviolet (UV) radiation are of paramount importance as commonly used Si photodetectors and photovoltaic cells suffer from poor UV response. Herein, we demonstrate the applications of graphene quantum dots (GQDs) as downconverters to sensitize Si photodiodes for extended and enhanced UV detection down to 300 nm and facilitating distinct visible response to UV wavelength-specific excitation. Stable blue (B-) and orange-red (R-) emitting nitrogen functionalized GQDs, synthesized by cost-effective solvothermal method, exhibit high photoluminescence (PL) quantum yield (57–62%), strong UV absorption, and large Stokes shift (130–250 nm). A scalable threefold improvement in UV response (330 nm) with a relative enhancement factor of 200% is recorded from a Si photodetector externally sensitized with visible-blind B-GQDs. The engineered combination of B- and R-GQDs in a tandem fashion exhibits distinct visible emission and facilitates bare-eye recognition of UV sub-bands. The present study provides a new pathway of UV detection with or without integrated devices by employing thin layers of solution-processed GQDs.

Optical Autocorrelation Measurement for Ultrafast Pulses at NIR Wavelengths Using GaP, GaAsP, and Si Photoconductive Detectors

In this article, we report on an optical real-time autocorrelator readout with a 5 Hz refresh rate, equipped with a transimpedance amplified photodetector based on the two-photon absorption (TPA) of semiconductor photodiodes (PDs) for ultrashort (1 &lt; ps) pulse measurement. By replacing the GaP PD of a commercial TPA detector with GaAsP and Si PD elements, we demonstrated that the spectral response based on the TPA of each photodetector followed the linear response of the corresponding semiconductor PD within accessible wavelength regions. The TPA spectral response of the GaAsP detector exhibited a peak at 1200 nm and a long wavelength limit near 1300 nm. The TPA spectral response of the Si detector exhibited a short wavelength limit near 1170 nm and a linear response up to 1300 nm. The two types of PD were compared with the characteristics of the GaP photodiode. These photoconductive detectors are efficient, compact, and robust sensors and can be used to diagnose the pulse characteristics of ultrafast fiber lasers and light sources near IR wavelengths.