Types Of Photodiodes Research Articles

Measurement and comparison of silicon p-i-n-photodiodes with ac impedance at different voltages

The dark alternating current (ac) parameters of commercially available silicon p-i-n-photodiodes are measured and compared at room temperature both in forward and reverse bias using the impedance spectroscopy technique. The ac behavior of the photodiodes is found to be almost the same. For bias voltages in the range from −0.8 to 0.0 V, the typical photodiode behaves like a pure capacitor. For higher voltages (V >-0.2 V) the impedance spectra are nearly semicircular and typically distorted on the high frequency side. At 0.2 V the distortion apparently arises from one of the two interfaces. However, at high bias voltages the nature of the distortion is attributed to the variation of photodiode capacitance and resistance with measurement frequency.

The Performance of X-Ray Scanner Using Ceramic Scintillator Base Detector Module

Using Eu-doped (Gd,Y) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ceramic scintillator and linear array 16-channel photodiodes, a detector module for X-ray scan inspection system was fabricated. Each Eu-doped (Gd,Y) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ceramic scintillator with a reflector based on the mixture of TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> powder and epoxy was coupled to a PIN type photodiode of 1.4 mm (W) and 3.2 mm (L). For a Data Acquisition System (DAS) of the full system, six detector module interface boards were fabricated. The detector interface board was able to obtain the digital scan data from 16 analog input channels by two ADCs with 8-channel analog input, in parallel. The output of ADC has a 16-bit serial data format to minimize the wire connection between the detector interface board and the main control board, to maximize the noise immunity of the resulting digital scan data. The measured signal to noise ratio (SNR) of the system was 61.73 dB and the system showed clear X-ray images for various materials and objects.

Development of Alpha Detector Module based on Large Area PIN Photodiode

Two alpha detectors based on scintillator coated PIN PD were manufactured and investigated for 3.5 MeV alpha particles. ZnO(Ga) and CsI(Tl) scintillators were coated on the large area of 1 cm × 1 cm PIN type photodiode, respectively. After connecting them with a charge sensitive preamplifier, system noise, signal output, and signal speed were measured and analyzed. Although the system noise after scintillator coating was increased, especially large in ZnO(Ga) coating, alpha detection was possible for both detectors. The output signal was relatively large in the CsI(Tl) coated detector compared with the ZnO(Ga) coated detector. In detection time test, the ZnO(Ga) coated detector showed the performance of about 3 times faster than the CsI(Tl) coated detector.

Analysis of interface states of metal–insulator–semiconductor photodiode with n-type silicon by conductance technique

A metal–insulator–semiconductor photodiode (MIS-PD) as active layer with n-type silicon as interdigitated Schottky electrodes has been fabricated. The current–voltage characteristics, density of interface states and photovoltaic properties of the MIS-PD diode have been investigated. The diode has a metal–insulator–semiconductor configuration with ideality factor higher than unity. The electronic parameters (ideality factor, series resistance and barrier height) of the diode were found to be 1.94, 2.23 × 10 4 Ω and 0.74, respectively. At voltages between 0.13 and 0.50 V, the charge transport mechanism of the diode is controlled by space charge-limited current mechanism. The interface state density of the diode was found to vary from 5.54 × 10 12 to 5.67 × 10 12 eV −1 cm −2 with bias voltage. The Au/SiO 2/n-Si/Al device shows a photovoltaic behavior with a maximum open circuit voltage V oc of 97.7 mV and short-circuit current I sc of 17.4 μA under lower illumination intensities. The obtained electronic parameters confirm that the Au/SiO 2/n-Si/Al diode is a MIS type photodiode.

A Wide-Dynamic-Range Photodiode-Type Active Pixel Sensor Cell with Seamlessly Combined Logarithmic–Linear–Logarithmic Response

A wide-dynamic-range photodiode-type (PD) active pixel sensor (APS) cell with seamlessly combined logarithmic–linear–logarithmic response is proposed for the first time and its operation is verified by circuit simulation. It has two additional metal–oxide–semiconductor field-effect transistors (MOSFETs) stacked in parallel to the reset MOSFET of conventional three-transistor (3-Tr) PD APS cells. By utilizing our previously proposed operation scheme that achieves automatic linear–logarithmic response switching, the proposed 5-Tr APS cell realizes seamlessly combined logarithmic–linear–logarithmic response.

Effect of Temperature on Bandwidth and Responsivity of Uni-Traveling-Carrier and Modified Uni-Traveling-Carrier Photodiodes

Temperature-dependent bandwidths and responsivities of uni-traveling-carrier (UTC) and modified uni-traveling-carrier (MUTC) photodiodes were theoretically and experimentally investigated. Theoretical and experimental responsivities of the UTC and MUTC photodiodes were improved as the operating temperature increased. On the other hand, each type of photodiode exhibited different temperature-dependent bandwidth characteristics depending on the thickness of the undoped photoabsorption layer. The bandwidth characteristics of the MUTC photodiode showed weak temperature dependence, which makes it suitable for application to outdoor optoelectronic converters.

The design of an active pixel sensor test structure optimised for the read out of scintillator screens

Indirect detection of X-rays using a scintillator coupled to a Solid-state sensor is an application where the CMOS Active Pixel Sensor (APS) can offer improved performance compared with conventional charge coupled device (CCD) based systems. The main advantages that CMOS sensors offer are reduced susceptibility to radiation damage, lower power consumption and increased on chip functionality. We describe the operation of a basic photodiode type pixel and explain how the read-out and sensing arrangement can be optimised for indirect X-ray detection in digital radiography applications. The optimised pixel is designed to have a narrow-band response to visible light generated by a scintillator screen, while at the same time suppressing signal from direct X-ray interaction. We outline a programme that has recently begun at Brunel University and e2v technologies to design, fabricate, and characterise variants of these pixel structures to perform a parametric study of CMOS imager performance.

Novel Operation Scheme for Realizing Combined Linear-Logarithmic Response in Photodiode-Type Active Pixel Sensor Cells

A novel operation scheme that realizes a combined linear-logarithmic response in conventional photodiode-type (PD) three-transistor (3-Tr) active pixel sensor (APS) cells is presented. It has been revealed that, by setting a reset transistor in weak inversion through properly selected bias voltages, conventional PD 3-Tr APS cells can be operated with a seamlessly combined linear-logarithmic response. A modification in the conventional APS cells that enhances their dynamic ranges in a linear response mode is also described.

Temperature dependence of the EUV responsivity of silicon photodiode detectors

Responsivity of silicon photodiodes was measured from -100 C to +50 C in the 3 to 250 nm wavelength range using synchrotron and laboratory radiation sources. Two types of silicon photodiodes were studied, the AXUV series having a thin nitrided silicon dioxide surface layer and the SXUV series having a thin metal silicide surface layer. Depending on the wavelength, the responsivity increases with temperature with the rates 0.013%/C to 0.053%/C for the AXUV photodiode and 0.020%/C to 0.084%/C for the SXUV photodiode. The increase in responsivity is consistent with the decrease in the silicon bandgap energy which causes a decrease in the pair creation energy. These results are particularly important for dose measurement in extreme ultraviolet (EUV) lithography steppers and sources since the detector temperature often increases because of the high EUV intensities involved.

Spatial non-uniformity analyses of radiometric detectors to identify suited transfer standards for optical radiometry

The non-uniformity of responsivity of photodiodes and thermal detectors limits the accuracy of their calibration. Spatial non-uniformity properties of a pyroelectric radiometer, a thermopile detector, silicon, germanium and indium gallium arsenide photodiodes are investigated in the scope of our work. Silicon type photodiodes showed best uniformity characteristics among the analysed photodiodes and detectors. Significant changes have been found in the spatial responsivity close to the band gap of silicon. The spatial responsivity of thermopile detector was measured at two different wavelengths and no wavelength dependence was observed.

Quantum well intermixing and MOCVD regrowth for monolithic integration of 40 Gbit∕s UTC type photodiodes with QW based components

A novel fabrication method for uni-travelling carrier (UTC) type photodiodes using quantum well (QW) intermixing and MOCVD regrowth is presented. This scheme will enable the monolithic integration of the photodiodes with high gain laser diodes, high efficiency electroabsorption modulators, and high saturation power semiconductor optical amplifiers. The photodiodes fabricated on intermixed quantum wells presented exhibit excellent photocurrent handling capabilities, minimal response roll-off over the 20 GHz of the testing capability, and open 40 Gbit/s eye diagrams.

Advanced detection systems for X-ray fluorescence excitation spectroscopy

This paper accounts for selected detector developments carried out over the past 15 years within the ESRF X-ray Absorption Spectroscopy group. This includes various types of photodiodes used as integrated current detectors. Special emphasis is put on the long-standing development of a Si drift-diode array suitable for energy-dispersive detection of X-ray fluorescence. This detector, which is now operational, was used to record high-quality XMCD/XAFS spectra on [Fe70Pt30] nanoparticles highly dispersed on a Si wafer. Using numerically deconvoluted spectra, energy resolution was decreased to 82 eV for the Si Kalphabeta line, 126 eV for the Fe Kalpha line and 176 eV for the Pt Lalpha line. A high-vacuum-compatible high-energy-resolution crystal analyzer was also installed on ID12, making it possible to record X-ray fluorescence excitation spectra in the photon-in/photon-out mode over a wide spectral range. Prospects of adapting these methods in order to investigate biological samples are briefly discussed.

Radiation tests of photodiodes for the ATLAS SCT and PIXEL opto-links

In previous research, epitaxial Si PIN photodiodes produced by Centronic which will be used in the ATLAS semiconductor tracker have been irradiated with 1 MeV neutrons and 24 GeV protons with fluences up to an equivalent of 10 15 1 MeV neutrons [1,2]. In this work 30 MeV proton beams were used to irradiate Centronic and Truelight epitaxial Si PIN diodes with accumulated fluences of up to 2.1×10 14–30 MeV p cm −2, an equivalent of 5.7×10 14 cm −2 1 MeV neutrons, to reach the pixel radiation environment. The responsivity was measured with different levels of fluence in order to study the responsivity behaviour of two different types of photodiodes. The responsivity behaviour of these two photodiodes was similar: a linear degradation at large fluences, >10 14 30 MeV p cm −2, but with different slopes. The response of the Centronic PIN diode showed a degradation to 73% after a proton fluence of 10 13 p cm −2 of 30 MeV and a linear degradation at a rate of −0.32% per 10 13 p cm −2 for fluences larger than 10 13 30 MeV p cm −2. The Truelight PIN degraded to 84% after a fluence of 10 13 p cm −2, with a linear degradation rate of –1.8% per 10 13 p cm −2. Annealing of both photodiodes with a bias voltage of –10 V for 180 h showed a 7% recovery for the Truelight PIN diode and a 2% recovery for the Centronic PIN diode after irradiation fluences of 2.1×10 14 p cm −2. A gamma source was also used to irradiate 6 Truelight PIN diodes with a total dose larger than 600 kGy; no obvious responsivity change was observed in this case.

Novel structure for large area image sensing

This work presents preliminary results in the study of a novel structure for a laser scanned photodiode (LSP) type of image sensor. In order to increase the signal output, a stacked p–i–n–p–i–n structure with an intermediate light-blocking layer is used. The image and the scanning beam are incident through opposite sides of the sensor and their absorption is kept in separate junctions by an intermediate light-blocking layer. As in the usual LSP structure the scanning beam-induced photocurrent is dependent on the local illumination conditions of the image. The main difference between the two structures arises from the fact that in this new structure the image and the scanner have different optical paths leading to an increase in the photocurrent when the scanning beam is incident on a region illuminated on the image side of the sensor, while a decreasing in the photocurrent was observed in the single junction LSP. The results show that the structure can be successfully used as an image sensor even though some optimization is needed to enhance the performance of the device.

Bioluminescent bioreporter integrated circuits: potentially small, rugged and inexpensive whole-cell biosensors for remote environmental monitoring.

1. SUMMARYA bioluminescent bioreporter integrated circuit (BBIC) is anovel whole-cell biosensor that combines the environmentalmonitoring capabilities of genetically engineered biolu-minescent micro-organisms (bioreporters) with optical appli-cation-specific integrated circuits. A BBIC device consistsof bioreporters sustained within a micro-environment, theintegrated circuit microluminometer, and a light-tightenclosure. The bioreporter typically contains the luxCDABEreporter genes encoding the enzymes required for biolumin-escence. In the presence of a targeted analyte, a gene(transcriptional) regulatory system induces the expressionof the luxCDABE genes. Analytical benchmark data forexposure of the bioreporter Pseudomonas fluorescens 5RLto salicylate was determined using a flow-through testsystem. The detection limit (after a 45 min exposure) wasca 50 lgl

Optical characterization of the silicon photodiodes for the establishment of national radiometric standards

Optical properties of the silicon photodiodes are investigated in the visible spectral regime. Non-linearity measurement standard was established by using Hamamatsu S1337-11 type windowless silicon photodiode whose non-linearity value was found to be better than 6×10 −5 at photocurrent level of 10 −9 to 10 −4 A . Temperature effects on the spectral responsivity for S1337-11, S1337-1010BQ and S1227-1010BQ type photodiodes were analyzed between 20°C and 40°C at 488.1, 514.7 and 632.8 nm vacuum wavelengths. The spatial uniformities of the responsivity for three type photodiodes are performed with a laser beam having 1 mm diameter by using home made two-axis micro translation system. Results of the reflectance measurements for three elements of reflection-based trap detectors were compared with the predicted values obtained from Fresnel equations.

Sensitivity penalty calculation for burst-mode receivers using avalanche photodiodes

This paper presents the sensitivity penalty for burst-mode receivers using avalanche photodiodes. The analysis takes into account detailed avalanche photodiode statistics, additive Gaussian noise, intersymbol interference and dc offsets in the receiver channel. The penalty has been calculated via comparison of bit-error rates (BERs), obtained using numerical integration, both in continuous- and burst-mode operation. Sensitivity penalties for burst-mode operation as a function of the mean avalanche gain are presented. The Gaussian approximation systematically underestimates the burst-mode penalty. It is shown that the penalty depends upon both the type of avalanche photodiode (APD) and the required BER. Optimum avalanche gains maximizing the sensitivity of the receiver are given. The influence of dc-offsets upon the sensitivity is studied. Furthermore, it is shown that the impulse response of the filters used to extract the decision threshold profoundly impacts the receiver performance. Finally, some important guidelines for the design of high sensitivity and wide dynamic range burst-mode receivers are given.

Unintended filtering in a typical photodiode detection system for optical tweezers

We characterize the frequency-dependent response of a photo detection system based on a Si-PIN photodiode and a laser with wavelength 1064 nm, a system commonly used with optical tweezers. We chopped the laser beam with chopper frequencies from 200 Hz to 14 kHz, and found an exponentially delayed response of the detection system with a characteristic delay time of ∼20 μs. The physical mechanism causing this time delay is silicon’s transparency to 1064 nm light: Photons are absorbed and create charge carriers not only in the diode’s depletion layer, where they are detected within nano-seconds, but predominantly in the n-layer, where they remain undetected till transported out by thermal diffusion. The diode’s response is dominated by this delay which can be characterized as a first-order low-pass filter with a 3dB-frequency of 8–9 kHz, depending on laser intensity. Measurements exploiting frequencies near or above this 3dB-frequency must be corrected for this unintended filter effect. We describe how to do this, and how to diagnose other systems which may or may not have the same problem. Explanations are intended for users of photo detection systems, and present the little semi-conductor physics needed to make sense.

Present status of radiometric quality silicon photodiodes

Evaluation of five types of silicon photodiode was undertaken to verify their suitability for absolute radiometry and also for their use as transfer standards in the spectral region from 1 nm to 1100 nm. Four types of photodiode were fabricated for this study; these were the p-on-n photodiode, n-on-p photodiodes with silicon dioxide front windows and n-on-p photodiodes with a metal-silicide front window. Fabrication of photodiodes with 100% internal quantum efficiency is demonstrated and their necessity for making absolute radiometric measurements with the lowest possible uncertainty is pointed out. The linearity characteristics of these devices, as measured by the ac/dc method, are far superior to those of the p-on-n diodes especially fabricated for this work and also to those exhibited by p-on-n diodes widely used at present by the radiometric community. Results on the stability of the quantum efficiency of the fabricated diodes after exposure to intense radiation of 13 nm, 120 nm, 157 nm, 193 nm and 254 nm radiation will also be presented. Photodiodes with a metal-silicide front window were the only devices stable when exposed to the intense beams of third-generation synchrotrons and UV excimer lasers.

Ultrafast &amp; Highly Efficient Resonant Cavity Enhanced Photodiodes

In this paper, we review our research efforts on resonant cavity enhanced (RCE) high-speed high-efficiency p-i-n and Schottky photodiodes (PDs) operating in the 1 st optical communication window. Using a microwave compatible planar fabrication process, we have designed and fabricated GaAs based RCE photodiodes. For RCE Schottky type photodiodes, we have achieved peak quantum efficiencies of 50% and 75% with semi-transparent (Au) and transparent (indium-tin-oxide) Schottky layers, respectively. Along with 3-dB bandwidths of 50 and 60 GHz, these devices exhibit bandwidth-efficiency (BWE) products of 25 GHz and 45 GHz respectively. For RCE p-i-n type photodiodes, we have fabricated and tested widely tunable devices with 92% quantum efficiency, along with a 3-dB bandwidth of 50 GHz, resulting in a 46 GHz BWE performance. These results correspond to the highest detector performances reported for vertically illuminated Schottky and p-i-n PDs in scientific literature.