Photodiode Circuit Research Articles

Impact of coherent core/shell architecture on fast response in InP-based quantum dot photodiodes.

Solution-processed, cadmium-free quantum dot (QD) photodiodes are compatible with printable optoelectronics and are regarded as a potential candidate for wavelength-selective optical sensing. However, a slow response time resulting from low carrier mobility and a poor dissociation of charge carriers in the optically active layer has hampered the development of the QD photodiodes with nontoxic device constituents. Herein, we report the first InP-based photodiode with a multilayer device architecture, working in photovoltaic mode in photodiode circuits. The photodiode showed the fastest response speed with rising and falling times of τ r = 4 ms and τ f = 9 ms at a voltage bias of 0 V at room temperature in ambient air among the Cd-free photodiodes. The single-digit millisecond photo responses were realized by efficient transportation of the photogenerated carriers in the optically active layer resulting from coherent InP/ZnS core/shell QD structure, fast separation of electron and hole pairs at the interface between QD and Al-doped ZnO layers, and optimized conditions for uniform deposition of each thin film. The results suggested the versatility of coherent core/shell QDs as a photosensitive layer, whose structures allow various semiconductor combinations without lattice mismatch considerations, towards fast response, high on/off ratios, and spectrally tunable optical sensing.

Placement Optimization of Infrared Sensors as Non-Invasive Blood Sugar Measurements

In the light of the increasing prevalence of diabetes, research on non-invasive blood sugar measuring devices have begun to be developed, one of which utilizes infrared spectroscopy methods. This method uses a pair of IR LED and photodiode placed in line. In doing so, the location of its placement in the human body has to be considered, thereby enabling the photodiode to capture the light emitted by the IR LED. Therefore, the voltage data generated by the photodiode circuit in several parts of the body is taken as the representation of the ability of the photodiode to absorb infrared light. A higher voltage value is captured in the range of 1 Volt when the sensor is on the finger. Meanwhile, there is no voltage read on the wrist. The results of this study will be used as a reference to determine the location of the sensor placement in the designed blood glucose monitoring device.

Development of photoelectric integrated single photon avalanche photodiode and front-end circuit based on BCD technology

Development of photoelectric integrated single photon avalanche photodiode and front-end circuit based on BCD technology

Coupled Equivalent Circuit for High-Speed Photodiodes

A coupled equivalent circuit for high-speed Si photodiodes is proposed, which is composed of a traditional resistance-capacitance-limited equivalent circuit and a carrier transit-limited equivalent circuit connected by a voltage controlled current source. All the resistances and capacitances in the carrier transit-limited equivalent circuit have physical meaning according to Laplace Transform. The proposed coupled equivalent circuit was applied to the Si p-i-n photodiodes and agreed well with the measured reflection coefficients and frequency response curves. Again, the minority carrier lifetime, diffusivity and interface state is verified to be the main limiting factors to the frequency response. This improved modeling can provide an effective way to design high speed photodiodes.

Design of Photodiode Circuit Based on Signal Acquisition

Most of optical signals is collected using optical instruments. Although photodiodes have the same unilateral conductivity as ordinary diodes, it can act as a photoelectric sensor in circuit and play a significant role in signal acquisition. In this study, the photosensitivity of photodiode was studied, a circuit was designed selecting photodiode as photoelectric sensor, and the signal acquisition was realized by testing the feasibility of the designed circuit. The equivalent model of the designed circuit was established by Pspice software, and the circuit performance under different illumination and bias voltage was simulated and analyzed. It is concluded that the photodiode circuit designed in this paper could effectively reflect the intensity of optical signals. When the optical signal was fixed, the increase of the reverse bias voltage in a certain range increased the photocurrent in the circuit; as a result, the signal was enhanced. The reverse bias voltage should not exceed 90 V; otherwise the dark current in the circuit would interfere with the detection of optical signals. The designed circuit can collect the pulse optical signal effectively and adjust the response characteristics of the circuit through the reverse bias voltage; the higher the bias voltage in a certain range, the better the response characteristics.

Analysis and Verification of a New Photoelectric-Motivated Memristor Based on Avalanche Photo-Diode

This work reports a device based on photoelectric-motivated memristor. In this paper, the simulation model of photoelectric-motivated memristor was established, and we stimulated the memristive characteristics by this model. The device goes from the non-triggered state to the triggered state, then back to non-triggered state and we obtained the simulation results. Then the current curve and the voltage curve fit a hysteresis loop of this device. The results of this memristive characteristics are verified by the test of the real photoelectric-motivated memristor device. According to the memristive properties of this device, it can be used to study the memristor circuit integrated with avalanche photo-diode and signal processing circuit, and applied in neural network and a new type of photoelectric memory.

Temperature Compensated Bias Supply Circuit for Photodiodes

Temperature Compensated Bias Supply Circuit for Photodiodes

Optical Sensor for Analysis of Amonia, Iron and Manganese Nutrients

The soil nutrients sensor is developed with the help of Light Emitting diodes (LEDs), Photodiode, microcontroller or microprocessor circuit and data logger system. The sensor is working on photometric principle and detects the soil nutrients. The wavelength of LED used as chemical agent and that is reacts with soil sample. The wavelength of LED is useful to detect nutrients like ammonia nitrogen (NHf4-N), iron (Fe), manganese (Mn) by colour changes with the help of different chemical reagent. The resolution of 1.0-20 mg/100 g has been performed for solution of soil nutrients. The samples are taken from different land and results are compared with database created for analysis.

Chaotic He-Ne laser

A He-Ne laser is an example of a class A laser, which can be described by a single nonlinear differential equation of the complex electric field. This laser system has only one degree of freedom and is thus inherently stable. A He-Ne laser can be driven to the chaotic condition when a large fraction of the output beam is injected back to the laser. In practice, this can be done simply by adding an external mirror. In this situation, the laser system has infinite degrees of freedom and therefore it can have a chaotic attractor. We show the fundamental laser equations and perform elementary stability analysis. In experiments, the laser intensity variations are measured by a simple photodiode circuit. The laser output intensity time series is studied using nonlinear analysis tools which can be found freely on the internet. The results show that the laser system with feedback has an attractor of a reasonably high dimension and that the maximal Lyapunov exponent is positive, which is clear evidence of chaotic behaviour. The experimental setup and analysis steps are so simple that the studies can even be implemented in the undergraduate physics laboratory.

CDS 전자눈 회로와 뇌 컴퓨터 연동 분광 문자 파형 인식

In a brain computer interface, visible wave recognition of memory sensing tasks is developed using the electric eye circuit of a cadmium sulfide photo diode (CDS). The probe was used for the chronocyclic voltammetry of three electrode systems. On the in vitro skin muscles, diagnostic neuro currents were varied using the muscle tension strength. Optimum detection parameters were explored - such as analytical potential windows, anodic and cathodic scan directions, and the amplified frequency. Other para meters were also examined. The statistic chrono cyclic detection limit sought was from the initial.-2.0 V to -0.8 V switching potential, as well as the 0.5 V/Sec scan rate. Diagnostic optimum results can be applied to in vivo memory detection on the muscles of forehead skin as well as on the surface of the back of the hand. This process can be used for muscle strength, thinking memory recognition and the brain-computer interface augment character control.

An Improved Measurement Method for the Strength of Radiation of Reflective Beam in an Industrial Optical Sensor Based on Laser Displacement Meter.

An optical sensor such as a laser range finder (LRF) or laser displacement meter (LDM) uses reflected and returned laser beam from a target. The optical sensor has been mainly used to measure the distance between a launch position and the target. However, optical sensor based LRF and LDM have numerous and various errors such as statistical errors, drift errors, cyclic errors, alignment errors and slope errors. Among these errors, an alignment error that contains measurement error for the strength of radiation of returned laser beam from the target is the most serious error in industrial optical sensors. It is caused by the dependence of the measurement offset upon the strength of radiation of returned beam incident upon the focusing lens from the target. In this paper, in order to solve these problems, we propose a novel method for the measurement of the output of direct current (DC) voltage that is proportional to the strength of radiation of returned laser beam in the received avalanche photo diode (APD) circuit. We implemented a measuring circuit that is able to provide an exact measurement of reflected laser beam. By using the proposed method, we can measure the intensity or strength of radiation of laser beam in real time and with a high degree of precision.

Elaboration of Conductive Polymer thin films (P3HT/PCBM) by spin coating method – Application for hybrid organic solar cell

The nanostructured polymer-fullerene thin film is one of the most prominent materials to make the hybrid bulk heterojunction solar cell (BHJ) with high conversion efficiency. Especially when the blend of P3HT and PCBM was used as the donor and acceptor materials. The properties of P3HT and PCBM layer in solar cell has been much studied and considered as high performance systems. One of the important factors for the high performance device is the fabrication of photo active layer with the appropriate thickness and morphology. In the ideal case, the intermolecular distance between the polymer and fullerene should be approximately 10-20 nm (the exciton diffusion distance) giving an area of extensive contact between the two phases. After the dissociation of carriers, the two polymer phases should create the path way for carriers to reach electrodes. But so far, this ideal configuration has not been published. In this work, we’ve elaborated the P3HT and PCBM photo active layers by spin coating methodon glass substrates covered ITO electrode. The rotational velocity was determined to get the necessary effective thickness of the polymer film. The annealing effect on structure, optical and electrical properties of the polymer thin film with different content of PCBM were also investigated. The experiments show the best device on electrode ITO has I-V characteristic as a photodiode and short circuit current (Isc) aboutmili-Ampere. These results demonstrate convincingly that polymer layers elaborated by spin coating method can result a good performance of the device.

Photodiode Circuits for Retinal Prostheses

Photodiode circuits show promise for the development of high-resolution retinal prostheses. While several of these systems have been constructed and some even implanted in humans, existing descriptions of the complex optoelectronic interaction between light, photodiode, and the electrode/electrolyte load are limited. This study examines this interaction in depth with theoretical calculations and experimental measurements. Actively biased photoconductive and passive photovoltaic circuits are investigated, with the photovoltaic circuits consisting of one or more diodes connected in series, and the photoconductive circuits consisting of a single diode in series with a pulsed bias voltage. Circuit behavior and charge injection levels were markedly different for platinum and sputtered iridium-oxide film (SIROF) electrodes. Photovoltaic circuits were able to deliver 0.038 mC/cm(2) (0.75 nC/phase) per photodiode with 50- μm platinum electrodes, and 0.54-mC/cm(2) (11 nC/phase) per photodiode with 50-μ m SIROF electrodes driven with 0.5-ms pulses of light at 25 Hz. The same pulses applied to photoconductive circuits with the same electrodes were able to deliver charge injections as high as 0.38 and 7.6 mC/cm(2) (7.5 and 150 nC/phase), respectively. We demonstrate photovoltaic stimulation of rabbit retina in-vitro, with 0.5-ms pulses of 905-nm light using peak irradiance of 1 mW/mm(2). Based on the experimental data, we derive electrochemical and optical safety limits for pixel density and charge injection in various circuits. While photoconductive circuits offer smaller pixels, photovoltaic systems do not require an external bias voltage. Both classes of circuits show promise for the development of high-resolution optoelectronic retinal prostheses.

Design and Implementation of a Photo Detector Using a Complementary Metal-Oxide Semiconductor

In this paper, we present a photo detector using a complementary metal-oxide semiconductor (CMOS) for plastic optical fiber (POF) applications. Generally, the PIN photodiode and optical receiver front-end circuit are made from III-V compound materials, such as GaAs, InP, and HEMT (High Electron Mobility Transistor), due to their high speed and low noise characteristics. However, silicon deep-submicron CMOS technology is more attractive due to its low cost and high integration capacity. A PIN photodiode using a CMOS suers from a low responsivity (R) a slow spreading speed of drift and diusion current generated by photon. To overcome the low responsivity of the CMOS PIN photodiode, we exploit a PN junction between the N-well and the P-substrate. We propose a finger-shaped arrangement of the P-substrate to compensate for the slow spreading speed of the drift currents. The implemented CMOS PIN photodiode exhibits 0.12-A/W responsivity and 4.5-pF parasitic capacitance. Also, the optical receiver front-end circuit for the POF applications is integrated with the CMOS PIN photodiode. The designed photo detector exhibits a 112-MHz 3-dB bandwidth and consumes only 3-mA of DC current from a single 3.3 V supply voltage.

Characterization of a Piezoelectric Buzzer Using a Michelson Interferometer

A piezoelectric material generates an electric potential across its surface when subjected to mechanical stress;1 conversely, the inverse piezoelectric effect describes the expansion or contraction of the material when subjected to some applied voltage. Piezoelectric materials are used in devices such as doorbell buzzers, barbeque igniters, and also as the scanning and approach mechanisms in scanning probing microscopy. The assembly of a scanning tunnelling microscope (STM)2 at Thompson Rivers University has motivated a characterization of the sensitivity and hysteresis3 of piezoelectric discs using a Michelson interferometer. The investigation uses an interferometer4 and a simple photodiode circuit to track the fringes. As a possible undergraduate lab, the measurement provides an introduction to piezoelectric materials (including hysteresis), the Michelson interferometer, and data acquisition techniques.

Investigation of the Internal Carrier Distribution in 4H-SiC Pin-Diodes by Laser Absorption Experiments

We present an experimental equipment for studying the charge carrier distribution in the interior of bipolar 4H-SiC high power devices by means of laser absorption measurements. Since the light absorption coefficient in a semiconductor depends on the electron and hole concentration, the attenuation of a laser beam transmitted through a sample is an integral function of the local charge carrier density. In order to detect the tiny changes in the light intensity caused by the plasma-optical effect, a highly sensitive measurement set-up has been developed. Its crucial components are a low-noise blue laser and a high-speed and broad-band photo-diode amplifier circuit. Sample preparation is sophisticated and requires special care. We investigated charge carrier profiles in 4H-SiC pin-diodes in the high-injection regime at current densities between 175 A/cm² and 350 A/cm². The measured charge carrier profiles are in good agreement with computer simulations.

Single Photon Counting Module Based on Large Area APD and Novel Logic Circuit for Quench and Reset Pulse Generation

We present the design, implementation, and characterization of a single-photon counting module (SPCM) based on large-area avalanche photodiode (APD) and new logic circuit based on TTL integrated circuits (ICs) for generating precise quench and reset delays. Low dark count rate, high linearity of 2 MHz, maximum dynamic range of 12 MHz, and minimum dead time of 35 ns have been achieved with 0.2 mm peltier-cooled single photon avalanche diode (SPAD) [model C30902S-DTC, Perkin Elmer Optoelectronics (PKI)]. The developed module was fiberized and tested for the detection of fluorescently labeled DNA sequences. Detection sensitivity at the level of single fluorescent molecule has been demonstrated.

Silicon Photo-Diode Using Surface-Plasmon Resonance

The concept of nano-photodiode, employing surface-plasmon antenna to create sub-wavelength size nearfield, is described in relation to silicon photonics. Response time of the prototype silicon nano-photodiode was much shorter (-20 ps) than that of conventional silicon photodiodes (>1 ns). There are two reasons for the high-speed response: short distance between electrodes (-100 nm) and small electrode area (< 1 μm2). The former is realized by lapping near-field region over depletion region (Schottky barrier) in silicon thereby eliminating time-consuming carrier diffusion process. The latter results in small electrode capacitance and thus reducing response time of the photodiode circuit. This nano-photodiode technology can be applied to other semiconductor materials such as germanium and ternary compound semiconductors.

P-174L: Late-News Poster: The System-LCD with Monolithic Ambient-Light Sensor System

We describe a newly developed 352×RGB×440 System-LCD that incorporates an ambient light sensor system comprising a lateral photo diode and analog processing circuits integrated directly onto the display substrate in CG-Silicon. By intelligently controlling the LCD backlight level in response to ambient lighting conditions we achieve low power consumption with high reliability at low cost.

Artifact Removal Procedure Distorts Multifocal Electroretinogram

Purpose: To study whether the Artifact Removal procedure available for eliminating artifacts in multifocal electroretinograms (mERG) works correctly or not. Methods: A test response was made using a photo-diode circuit. mERGs were recorded from 3 well-trained normal subjects using the Veris III system, and were then analyzed by the procedure that is included in the Veris Science (Artifact Removal) software program. The stimuli consisted of densely arranged arrays of 103 or 37 hexagonal elements. It took a total of 8 minutes to obtain one mERG record, and 16 sessions were required to complete this record. The first-order as well as the second-order kernel response components were extracted by Veris Science software, and the Artifact Removal procedure was used for both components. Results: The Artifact Removal procedure influenced both the test response on the center element as well as the neighboring traces just around the test response. After the repetitions of the Artifact Removal procedure, the shape of the test response changed considerably. Some of the traces of the second-order kernel response components elicited from a normal subject changed irregularly when the Artifact Removal procedure was repeatedly used. The noise increased at the first iteration of the Artifact Removal procedure. Conclusion: This procedure has been considered useful for eliminating artifact distortion in mERG, but should be carefully checked by well-established testing methods before clinical use.