Showing papers on "Photodiode published in 2007"

Recent Advances in Telecommunications Avalanche Photodiodes

Abstract: For high-bit-rate long-haul fiber optic communications, the avalanche photodiode (APD) is frequently the photodetector of choice owing to its internal gain, which provides a sensitivity margin relative to PIN photodiodes. APDs can achieve 5-10-dB better sensitivity than PINs, provided that the multiplication noise is low and the gain-bandwidth product is sufficiently high. In the past decade, the performance of APDs for optical fiber communication systems has improved as a result of improvements in materials and the development of advanced device structures. This paper presents a brief review of APD fundamentals and describes some of the significant advances

High-performance 4H-SiC-based ultraviolet p-i-n photodetector

Abstract: A high-performance 4H-SiC p-i-n photodetector for visible-blind ultraviolet (UV) applications has been designed and fabricated. The electrical and optical characteristics were measured at room temperature. The photodetector suffered from significant dark current of 2.5 pA/mm2 at reverse bias of 5 V, and the UV light photocurrent was larger than four orders of magnitude higher than the dark current. The built-in potential and the unintentional i-layer doping concentration were obtained from capacitance-voltage (C-V) measurements. The spectral peak responsivity of the detector reached 0.13 A/W at a wavelength of 270 nm, corresponding to a maximum external quantum efficiency of ∼61%. And the ratio of responsivity at 270 nm to that at 380 nm was >103. The characteristics imply that the photodetector has a great improved ultraviolet-visible rejection ratio which is needed for ultraviolet signal detection.

CMOS-Compatible All-Si High-Speed Waveguide Photodiodes With High Responsivity in Near-Infrared Communication Band

Abstract: Submicrometer silicon photodiode waveguides, fabricated on silicon-on-insulator substrates, have photoresponse from <1270 to 1740 nm (0.8 AW-1 at 1550 nm) and a 3-dB bandwidth of 10 to 20 GHz. The p-i-n photodiode waveguide consists of an intrinsic waveguide 500times250 nm where the optical mode is confined and two thin, 50-nm-thick, doped Si wings that extend 5 mum out from either side of the waveguide. The Si wings, which are doped one p-type and the other n-type, make electric contact to the waveguide with minimal effect on the optical mode. The edges of the wings are metalized to increase electrical conductivity. Ion implantation of Si+ 1times10 13 cm-2 at 190 keV into the waveguide increases the optical absorption from 2-3 dBmiddotcm-1 to 200-100 dBmiddotcm-1 and causes the generation of a photocurrent when the waveguide is illuminated with subbandgap radiation. The diodes are not damaged by annealing to 450 degC for 15 s or 300 degC for 15 min. The photoresponse and thermal stability is believed due to an oxygen stabilized divacancy complex formed during ion implantation

A CMOS 3-D Imager Based on Single Photon Avalanche Diode

Abstract: A 64-pixel linear array aimed at 3-D vision applications is implemented in a high-voltage 0.8 mum CMOS technology. The detection of the incident light signals is performed using photodiodes biased above breakdown voltage so that an extremely high sensitivity can be achieved exploiting the intrinsic multiplication effect of the avalanche phenomenon. Each 38times180-mum2 pixel includes, besides the single photon avalanche diode, a dedicated read-out circuit for the arrival-time estimation of incident light pulses. To increase the distance measurement resolution a multiple pulse measurement is used, extracting the mean value of the light pulse arrival-time directly in each pixel; this innovative approach dramatically reduces the dead-time of the pixel read-out, allowing a high frame rate imaging to be achieved. The sensor array provides a range map from 2 m to 5 m with a precision better than plusmn0.75% without any external averaging operation. Moreover, with the same chip, we have explored for the first time the implementation of an indirect time-of-flight measurement by operating the proposed active pixel in the photon counting mode

Very high quantum efficiency in type-II InAs/GaSb superlattice photodiode with cutoff of 12 μm

Abstract: The authors report the dependence of the quantum efficiency on device thickness of type-II InAs∕GaSb superlattice photodetectors with a cutoff wavelength around 12μm. The quantum efficiency and responsivity show a clear delineation in comparison to the device thickness. An external single-pass quantum efficiency of 54% is obtained for a 12μm cutoff wavelength photodiodes with a π-region thickness of 6.0μm. The R0A value is kept stable for the range of structure thicknesses allowing for a specific detectivity (2.2×1011cmHz∕W).

Characterization of the First Prototypes of Silicon Photomultiplier Fabricated at ITC-irst

Abstract: This paper reports on the electrical characterization of the first prototypes of Geiger-Mode Avalanche Photodiodes (GM-APDs) and Silicon Photomultipliers (SiPMs) produced at ITC-irst, Trento. Both static and functional measurements have been performed in dark condition. The static tests, consisting in reverse and forward IV measurements, have been performed on 20GM-APDs and 90 SiPMs. The breakdown voltage, the quenching resistance value and the current level have been proved to be very uniform. On the other hand, the analysis of the dark signals allowed the extraction of important properties such as the dark count rate, the gain, the after-pulse and optical cross-talk (in case of the SiPMs) rates. These parameters have been evaluated as a function of the bias voltage, showing trends perfectly compatible with the theory of the device

Organic light emitting device and method of manufacturing the same

Abstract: An organic light emitting device and a manufacturing method thereof are provided to reduce a size of a display device by decreasing a size of a photodiode An organic light emitting device includes a substrate(100), a transistor, an OLED(Organic Light Emitting Diode), a photodiode, and a reflective film(110) The transistor is formed on the substrate and includes a gate, a source, and a drain The OLED is connected to the transistor and includes a first electrode(180), an organic film(210), and a second electrode(220) The photodiode generates an electrical signal according to incident light The reflective film is formed under the photodiode and reflects the incident light toward the photodiode A brightness of the light emitted from the OLED is varied according to the electrical signal from the photodiode

InGaAsP–InP Avalanche Photodiodes for Single Photon Detection

Abstract: In this paper, we describe the design, characterization, and modeling of InGaAsP/InP avalanche diodes designed for single photon detection at wavelengths of 1.55 and 1.06 mum. Through experimental and theoretical work, we investigate critical performance parameters of these single photon avalanche diodes (SPADs), including dark count rate (DCR), photon detection efficiency (PDE), and afterpulsing. The models developed for the simulation of device performance provide good agreement with experimental results for all parameters studied. For 1.55-mum SPADs, we report the relationship between DCR and PDE for gated mode operation under a variety of operating conditions. We also describe in detail the dependence of afterpulsing effects on numerous operating conditions, and in particular, we demonstrate and explain a universal functional form that describes the dependence of DCR on hold-off time at any temperature. For 1.06-mum SPADs, we present the experimentally determined relationship between DCR and detection efficiency for free-running operation, as well as simulations complementing the experimental data.

PbSe nanocrystal/conducting polymer solar cells with an infrared response to 2 micron

Abstract: We investigated the photovoltaic response of nanocomposites made of colloidal, infrared-sensitive, PbSe nanocrystals (NCs) of various sizes and conjugated polymers of either regioregular poly (3-hexylthiophene) (RR-P3HT) or poly- (2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene) (MEH-PPV). The conduction and valence energy levels of PbSe NCs were determined by cyclic voltammetry and revealed type II heterojunction alignment with respect to energy levels in RR-P3HT for smaller NC sizes. Devices composed of NCs and RR-P3HT show good diode characteristics and sizable photovoltaic response in a spectral range from the ultraviolet to the infrared. Using these materials, we have observed photovoltaic response at wavelengths as far to the infrared as 2 μm (0.6 eV), which is desirable due to potential benefits of carrier multiplication (or multi-exciton generation) from a single junction photovoltaic. Under reverse bias, the devices also exhibit good photodiode responses over the same spectral region.

Schottky ultraviolet photodiode using a ZnO hydrothermally grown single crystal substrate

Abstract: A Schottky ultraviolet photodiode using a (0001) ZnO single crystal grown by the hydrothermal growth method is reported. The photodiode consisted of a semitransparent Pt film for the Schottky electrode and an Al thin film for the Ohmic electrode. The photodiode had polarity dependences on current-voltage characteristics and on responsivity. In the case of the Schottky electrode on the zinc surface, the responsivity was 0.185A∕W at a wavelength of 365nm. On the other hand, the responsivity was 0.09A∕W for an oxygen surface. The results are attributed to the polarity dependences of surface chemical reactivity and the surface state density on ZnO surfaces.

Hole-initiated multiplication in back-illuminated GaN avalanche photodiodes

Abstract: Avalanche p-i-n photodiodes were fabricated on AlN templates for back illumination. Structures with different intrinsic layer thicknesses were tested. A critical electric field of 2.73MV∕cm was estimated from the variation of the breakdown voltage with thickness. From the device response under back and front illumination and the consequent selective injection of holes and electrons in the junction, ionization coefficients were obtained for GaN. The hole ionization coefficient was found to be higher than the electron ionization coefficient as predicted by theory. Excess multiplication noise factors were also calculated for back and front illumination, and indicated a higher noise contribution for electron injection.

Integrated thin-film polymer/fullerene photodetectors for on-chip microfluidic chemiluminescence detection

Abstract: We report the use of solution-processed thin-film organic photodiodes for microscale chemiluminescence. The active layer of the photodiodes comprised a 1 : 1 blend by weight of the conjugated polymer poly(3-hexylthiophene) [P3HT] and [6,6]-phenyl-C(61)-butyric acid-methylester [PCBM]--a soluble derivative of C(60). The devices had an active area of 1 mm x 1 mm, and a broad-band response from 350 to 700 nm, with an external quantum efficiency of more than 50% between 450 and 550 nm. The photodiodes have a simple layered structure that permits facile integration with planar chip-based systems. To evaluate the suitability of the organic devices as integrated detectors for microscale chemiluminescence, a peroxyoxalate based chemiluminescence reaction (PO-CL) was monitored within a poly(dimethyl-siloxane) (PDMS) microfluidic device. Quantitation of hydrogen peroxide indicated excellent linearity and yielded a detection limit of 10 microM, comparable with previously reported results using micromachined silicon microfluidic chips with integrated silicon photodiodes. The combination of organic photodiodes with PDMS microfluidic chips offers a means of creating compact, sensitive and potentially low-cost microscale CL devices with wide-ranging applications in chemical and biological analysis and clinical diagnostics.

Wide bandgap UV photodetectors: a short review of devices and applications

Abstract: Ultraviolet detectors are of a great interest to a wide range of industrial, military, environmental and even biological applications. This paper intends first to review some of the most relevant recent developments in the field of wide bandgap semiconductor UV detectors, and to give an overview of their applications. A special focus is given on III-nitride based devices, which more and more clearly represent to date one of the most promising and flexible technical solutions for UV detection. Keywords : ultraviolet detectors, wide bandgap semiconduc tors, Si photodiode, SiC photodiode, diamond, III-nitrides 1. INTRODUCTION The ultraviolet (UV) light spectral range starts from the visible (400 nm, 3.1 eV) and reaches the X-ray spectral low energy frontier (10 nm, 124 eV). It can be divided in 4 spectral regions : - UV A, for wavelengths between 400 and 320 nm (from 3.1 to 3.87 eV), - UV B, for wavelengths between 320 et 280 nm (from 3.87 to 4.43 eV), - UV C, for wavelengths between 280 et 200 nm (from 4.43 to 6.20 eV), - Far UV, for wavelengths between 200 et 10 nm ( from 6.2 to 124 eV). Given its specific light absorption properties, the earth atmosphere does not allow the free propagation of a light whose wavelength is shorter than 200 nm : the far UV spectrum located in the 200 – 10 nm therefore needs a high level of vacuum to propagate, and for that reason is very commonly called “vacuum UV” (VUV). Relevant applications of UV detectors are as follows : - Emitters calibration : UV dosimetry and imaging, incl uding solar UV measurements and astronomical studies, - Flame sensors (fire alarm systems, missile plume detection, combustion engine control), - Spatial optical communications (intra- and inter-satellite secured communications), - Biological and chemical sensors (ozone detection, determination of pollution levels in air, biological agents detection etc.).

Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation.

Abstract: Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.

High resolution gamma ray tomography scanner for flow measurement and non-destructive testing applications.

Abstract: We report on the development of a high resolution gamma ray tomography scanner that is operated with a Cs-137 isotopic source at 662 keV gamma photon energy and achieves a spatial image resolution of 0.2 line pairs/ mm at 10% modulation transfer function for noncollimated detectors. It is primarily intended for the scientific study of flow regimes and phase fraction distributions in fuel element assemblies, chemical reactors, pipelines, and hydrodynamic machines. Furthermore, it is applicable to nondestructive testing of larger radiologically dense objects. The radiation detector is based on advanced avalanche photodiode technology in conjunction with lutetium yttrium orthosilicate scintillation crystals. The detector arc comprises 320 single detector elements which are operated in pulse counting mode. For measurements at fixed vessels or plant components, we built a computed tomography scanner gantry that comprises rotational and translational stages, power supply via slip rings, and data communication to the measurement personal computer via wireless local area network.

Near bulk-limited R0A of long-wavelength infrared type-II InAs/GaSb superlattice photodiodes with polyimide surface passivation

Abstract: Effective surface passivation of type-II InAs∕GaSb superlattice photodiodes with cutoff wavelengths in the long-wavelength infrared is presented. A stable passivation layer, the electrical properties of which do not change as a function of the ambient environment nor time, has been prepared by a solvent-based surface preparation, vacuum desorption, and the application of an insulating polyimide layer. Passivated photodiodes, with dimensions ranging from 400×400to25×25μm2, with a cutoff wavelength of ∼11μm, exhibited near bulk-limited R0A values of ∼12Ωcm2, surface resistivities in excess of 104Ωcm, and very uniform current-voltage behavior at 77K.

CMOS-Based Active Pixel for Low-Light-Level Detection: Analysis and Measurements

Abstract: An analysis of the active pixel sensor (APS), considering the doping profiles of the photodiode in an APS fabricated in a 0.18 mum standard CMOS technology, is presented. A simple and accurate model for the junction capacitance of the photodiode is proposed. An analytic expression for the output voltage of the APS obtained with this capacitance model is in good agreement with measurements and is more accurate than the models used previously. A different mode of operation for the APS based on the dc level of the output is suggested. This new mode has better low-light-level sensitivity than the conventional APS operating mode, and it has a slower temporal response to the change of the incident light power. At 1 muW/cm2 and lower levels of light, the measured signal-to-noise ratio (SNR) of this new mode is more than 10 dB higher than the SNR of previously reported APS circuits. Also, with an output SNR of about 10 dB, the proposed dc level is capable of detecting light powers as low as 20 nW/cm2, which is about 30 times lower than the light power detected in recent reports by other groups.

InGaAs–InP Photodiodes With High Responsivity and High Saturation Power

Abstract: InGaAs-InP modified charge compensated uni- traveling carrier photodiodes with both absorbing and nonabsorbing depleted region are demonstrated. The fiber-coupled external quantum efficiency was 60% (responsivity at 1550 nm = 0.75 A/W). A 40-mum-diameter photodiode achieved 14-GHz bandwidth and 25-dBm RF output power and a 20-mum-diameter photodiode exhibited 30-GHz bandwidth and 15.5-dBm RF output power. The saturation current-bandwidth products are 1820 mA ldr GHz and 1560 mA GHz for the 40-mum-diameter and 40-mum-diameter devices, respectively.

Ge-on-SOI-Detector/Si-CMOS-Amplifier Receivers for High-Performance Optical-Communication Applications

Abstract: In this paper, an overview and assessment of high-performance receivers based upon Ge-on-silicon-on-insulator (Ge-on-SOI) photodiodes and Si CMOS amplifier ICs is provided. Receivers utilizing Ge-on-SOI lateral p-i-n photodiodes paired with high-gain CMOS amplifiers are shown to operate at 15 Gb/s with a sensitivity of -7.4 dBm (BER=10-12) while utilizing a single supply voltage of only 2.4 V. The 5-Gb/s sensitivity of similar receivers is constant up to 93 degC, and 10-Gb/s operation is demonstrated at 85 degC. Error-free (BER<10-12) operation of receivers combining a Ge-on-SOI photodiode with a single-ended high-speed receiver front end is demonstrated at 19 Gb/s, using a supply voltage of 1.8 V. In addition, receivers utilizing Ge-on-SOI photodiodes integrated with a low-power CMOS IC are shown to operate at 10 Gb/s using a single 1.1-V supply while consuming only 11 mW of power. A perspective on the future technological capabilities and applications of Ge-detector/Si-CMOS receivers is also provided

Single Schottky-barrier photodiode with interdigitated-finger geometry: Application to diamond

Abstract: The authors propose a single Schottky-barrier photodiode (SPD) with interdigitated Ohmic and Schottky contacts. A homoepitaxial diamond layer with low boron concentration has been utilized as an example for the fabrication of solar-blind deep-ultraviolet detector. This device structure enables the operations in both photoconductive mode with large photocurrent gain and depletion mode with fast response speed. The photosensitivity and spectral response of such kind of device are greatly improved when compared with a conventional SPD with semitransparent dotted Schottky contact. The present device structure can be extended to other semiconductor photodetectors.

Secondary scintillation yield in pure xenon

Abstract: The xenon secondary scintillation yield was studied as a function of the electric field in the scintillation region, in a gas proportional scintillation counter operated at room temperature. A large area avalanche photodiode was used for the readout of the VUV secondary scintillation produced in the gas, together with the 5.9 keV x-rays directly absorbed in the photodiode. The latter was used as a reference for the determination of the number of charge carriers produced by the scintillation pulse and, thus, the number of VUV photons impinging the photodiode. A value of 140 photons/kV was obtained for the scintillation amplification parameter. The attained results are in good agreement with those predicted, for room temperature, by Monte Carlo simulation and Boltzmann calculations, as well as with those obtained for saturated xenon vapour, at cryogenic temperatures, and are about a factor of two higher than former results measured at room temperature.

Micro concentrators elastically coupled with spherical photovoltaic cells

Abstract: With small dimensional optics, small photovoltaic cells have heat distribution surfaces, very high concentrations and subsequently high utilization of the semiconductors can be achieved. Discrete photodiodes can be formed as spherical and other geometric shaped, cells with high performance characteristics, precision dimensions, and low cost. This invention positions discrete photovoltaic cells by using their geometric shape, elastic electrical mounts, couples them to small optical concentrator systems of refractory and or reflective optics and makes electrical network connections to those photodiodes, reliably, adjusting for thermal expansion, and at low cost to form low cost and reliable electrical power arrays. The electrical connectors and network can form part of the reflective optics and heat removal system. The electrical interconnection system can also form a reliable network that is self-correcting and tolerant of point failures.

Active Pixel Concept Combined With Organic Photodiode for Imaging Devices

Abstract: The active pixel concept is a promising architecture for imaging systems. We report on the electrooptical characterization of a hybrid organic active pixel sensor (APS) where an organic photodiode is integrated on top of an amorphous silicon thin-film transistor circuitry, which drives the image sensor and performs the signal processing. The active pixel approach provides an on-pixel amplification of the signal with a charge gain of up to 10. A fill factor that is close to 100% is obtained by embedding all transistors underneath the organic photodetector. We show that, as compared with organic passive pixels, the organic APS shows a higher sensitivity, making the detection of smaller signals possible.

High-Performance InGaAs/InP Single-Photon Avalanche Photodiode

Abstract: In0.53Ga0.47As/InP avalanche photodiodes with very low dark current have been characterized in gated mode for single-photon detection. A 40-mum-diameter single-photon avalanche diodes (SPAD) exhibited high single-photon detection efficiency (SPDE = 45% at 1.31 mum), low dark count rate (DCR = 12 kHz), and low noise-equivalent power (NEP=4.5X 10-17W/Hz1/2 W/Hz) at 200 K and 1.31 mum. A timing resolution of 140 ps was achieved with an SPDE of 45%. In addition, the dark current and DCR of a 4X4 SPAD array are reported.

Geiger mode avalanche photodiode

Abstract: An avalanche mode photodiode array (102) is fabricated using a silicon on insulator wafer and substrate transfer process. The array includes a plurality of photodiodes (100). The photodiodes (100) include an electrically insulative layer (206), a depletion region (204), and first (208) and second (210) doped regions. An interconnection layer (212) includes electrodes (214, 216) which provides electrical connections to the photodiodes. The photodiode array (102) is carried by a handle wafer (217).

Ultraviolet Single Photon Detection With Geiger-Mode 4H-SiC Avalanche Photodiodes

Abstract: We report 4H-SiC avalanche photodiodes operated in Geiger mode for single photon detection at 265 nm. At room temperature, the single photon detection efficiency is 14% with a dark count probability of 1.7 x 10-4. Since the external quantum efficiency is 21% at 265 nm, it follows that 65% of the absorbed photons are counted as avalanche events. The jitter of the photodiodes is also characterized.

Low Dark-Current Germanium-on-Silicon Near-Infrared Detectors

Abstract: We demonstrate near-infrared Ge-on-Si photodiodes designed to minimize the dark current density and fabricated by chemical vapor deposition. The p-i-n detectors exhibit record low dark currents of 7 nA at 1-V reverse bias with responsivities close to the theoretical maximum. An excellent performance is ascertained even for very low reverse voltages.

Free-running InGaAs/InP Avalanche Photodiode with Active Quenching for Single Photon Counting at Telecom Wavelengths

Abstract: We present an InGaAs∕InP avalanche photodiode with an active quenching circuit on an application specific integrated circuit (ASIC) that is capable of operating in both gated and free-running modes. The 1.6mm2 ASIC chip is fabricated using complementary metal oxide semiconductor technology guaranteeing long-term stability, reliability, and compactness. In the free-running mode, we find a single photon detection efficiency of 10% with <2kHz of noise.

Effects of optical coupling in III-V multilayer systems

Abstract: A method to visualize and investigate radiative recombination processes in compound semiconductor materials by utilizing the effect of optical coupling in III-V multilayer systems is presented. For this purpose, a semiconductor material of interest is grown on an activated germanium (Ge) substrate which then serves as a photodiode. By means of spectral response measurements of the Ge photodiode, a response signal from the upper layers can be detected. It is proven both by experiment and by modeling that the signals from these layers can only be explained by optical transport mechanisms, i.e., radiative recombination.