PIN-type Photodiode Research Articles

Large and tunable optoelectronic chromatic dispersion in PIN-type photodiodes.

It is known that PN-type photodiodes possess high optoelectronic chromatic dispersion (OED). Here we present a theoretical and experimental study of OED in PIN-type photodiodes. Applying the modulation phase-shift technique, a Ge PIN photodiode exhibits ∼0.5 deg/nm phase-shift sensitivity at 10 MHz modulation, corresponding to a dispersion of 1.4 ×109ps/(n m ×k m), many orders of magnitude larger than high-dispersion optical materials such as chalcogenide glass. A striking feature of the PIN device is the ability to tune the amount and sign of the OED through the bias voltage. Electronic tuning between -0.8 deg/nm and +0.5 deg/nm is shown. The PIN photodiode is an on-chip device possessing significant tunable dispersion for applications in optical sensing and spectroscopy.

A PIN photodiode ionizing radiation detector with small angular dependence and low buildup

PurposeTo develop an improved PIN photodiode detector that has low angular dependence and small buildup. Show that the measured dose compares well with the dose calculated by a treatment planning system for static fields at oblique angles and rotationally delivered fields. MethodsCommercially available PIN photodiodes, VEMD1060X01, (Vishay Semiconductor, Shelton, CT), are fabricated into detectors that can be used for measurement of ionizing radiation. PIN photodiodes are soldered onto coaxial cables in an edge-on orientation and are mounted in a symmetrical package. Detector signals are measured with an electrometer with zero input bias voltage. Dose is measured from a Varian Trilogy (Varian Medical Systems, Milpitas, CA) linear accelerators 6 MV photon and 6 MeV electron beams. An Eclipse (Varian Medical Systems, Milpitas, CA) commercial treatment planning system Acuros and electron Monte Carlo algorithms are used for calculating dose expected in various irradiation geometries. ResultsThe single diode detector has an angular dependence between −1.1% and +1.2% and a buildup of 0.6 mm water equivalence. Measurements of dose at 0.3, 0.5, 1.0 and 1.5 cm depth from oblique static beams and from intensity modulated radiation therapy (IMRT) delivered beams agree with planning system calculations within ±1.5%. ConclusionsA clinically useable dose detector can be fabricated from a PIN type photodiode. This diode detector can be used to measure dose at the surface of a patient under a bolus if one is used. Measurements agree with calculations for static fields at oblique angles as well as rotational IMRT delivered beams.

Analysis of transient signal broadening of silicon-based photodiodes irradiated by nanosecond laser

To investigate the saturation characteristics of silicon-based optoelectronic devices caused by short-pulse laser irradiation, an Nd:YAG laser with a wavelength of 1064 nm and two typical silicon-based photodiodes, PN and PIN, were employed to build an experimental system to measure the transient response signal of the device. The change. The experimental results demonstrate that with the increase of laser energy density, the nonlinear saturation of the two devices occurs, and the response time is significantly increased. This is a response degradation phenomenon for the response of the device and the signal after the saturation of the two devices. By analyzing the rising edge, half-height width, and bottom width of the characteristic quantity, it can be found that the broadening of the two devices is mainly due to the broadening of the falling edge of the response signal. However, the broadening of the PIN-type photodiode after laser irradiation is compared with that of PN. Type photodiodes remain more remarkable. Through the analysis of carrier dynamics, when the signal is restored, the movement of carriers is affected by a large number of photogenerated carriers after the laser irradiation ends, affecting the drift movement and space charge region during the bipolar transport of carriers. The width of the two devices attenuates the speed when the signals of the two devices are restored, leading to the saturation caused by the laser irradiation of the two devices

Design and simulation of Mg<sub>2</sub>Si/Si avalanche photodiode

InGaAs and HgCdTe materials are widely used in short wave infrared photodetectors, which contain heavy metal elements. The massive use of the heavy metal elements naturally results in their scarcity, and the nonnegligible environmental pollution. Searching for other suitable materials for infrared devices becomes a key to solving the above problems. As a kind of abundant and eco-friendly material, Mg<sub>2</sub>Si has a high absorption coefficient in the near-infrared band. Its application in infrared detector makes it possible to replace the infrared devices containing toxic elements on the market in the future. The Mg<sub>2</sub>Si/Si avalanche photodiode(APD) with separation structure of absorption layer, charge layer and multiplication layer, with Mg<sub>2</sub>Si serving as the absorption layer, is constructed by using the Atlas module in Silvaco software. The effects of the thickness and doping concentration of the charge layer and multiplier layer on the distribution of internal electric field, punch-through voltage, breakdown voltage (<i>V</i><sub>b</sub>), <i>C-</i><i>V</i> characteristics, and transient response of Mg<sub>2</sub>Si/Si SACM-APD are simulated. The effects of bias voltage on the <i>I-</i><i>V</i> characteristics and spectral response are analyzed. The punch-through voltage, breakdown voltage, dark current density, gain coefficient (<i>M</i><i><sub>n</sub></i>) and the current amplification factor (<i>M</i>) after avalanche effect of APD are obtained after the structure optimization. According to the simulation results, the spectral response wavelength of the device is extended to 1.6 μm, so the selection of Mg<sub>2</sub>Si as the absorption layer effectively extends the spectral response band of Si based APD. When the wavelength of incident light is 1.31 µm and the optical power is 10 mW/cm<sup>2</sup>, the obtained punch-through voltage is 17.5 V, and the breakdown voltage is 50 V. When the bias voltage is 47.5 V (0.95<i>V</i><sub>b</sub>), the peak value of spectral response is 25 A/W at a wavelength of 1.1 μm, a density of dark current is about 3.6 × 10<sup>–5</sup> A/cm<sup>2</sup>, a multiplication factor <i>M</i><i><sub>n</sub></i> is 19.6, and <i>M</i><i><sub>n</sub></i> achieves a maximum value of 102 when the device is broken down. Meanwhile, the current amplification factor <i>M</i> after avalanche effect is 75.4, and the current gain effect of the SACM structure is obvious. The peak value of spectral response for the pin-type photodiode in the previous study is only 0.742 A/W. Comparing with the pin-type photodiode, the spectral response of Mg<sub>2</sub>Si/Si SACM-APD is greatly improved. In this work, the structure parameters of the device are optimized, which lays a nice foundation for fabricating the high-performance devices.

Investigation of defects influencing performance of type-II InAs/GaInSb superlattice based infrared PIN type photodetectors

We report on an investigation of dark current contributions from common microscale crystallographic defects in type-II InAs/GaInSb superlattice infrared PIN type photodiode structures grown on (100) GaSb substrates and have identified three general classifications. Defects on several wafers of varying design were examined from multiple perspectives to correlate electrical activity with structural properties, to develop the identification and classification scheme. Active defects were first identified by current density vs voltage (J-V) measurements and electron beam induced current (EBIC) scans of individual diodes with micrometer resolution. The EBIC scans were then correlated with plan-view optical and atomic force microscopy images, both before and after anisotropic etch-pit analysis using a newly developed etchant. The atomic scale structure of active and inactive defects was then compared using cross-sectional transmission electron microscopy (TEM) on vertical slices of defects extracted using focused ion beam milling. Analysis of the TEM images yielded important clues as to the structure and root causes of benign and active defects, in which only significant disruptions at the epi-substrate interface appear to play a key role in producing microscale defects that efficiently promote dark current.

Investigation of thermal treatment on improving the performance behavior of Si PIN alpha radiation detectors

The silicon-based PIN-type photodiode was designed and fabricated employing conventional bipolar planar technology using different annealing process to reduce the leakage current and detector energy resolution. In this process the effects of the Annealing and gas flow rate on the detector electrical properties such as capacitance-voltage (C–V) of MOS capacitors and current-voltage (I–V) of diodes and alpha spectral measurement are specified. Silicon PIN radiation detectors are made on four similar fabrication process with different post thermal annealing at constant temperature and different hydrogen gas flow (10 sccm–60 sccm). The study results proves that the detector with 15 sccm hydrogen gas flow shows lower leakage current due to the lower remained interface traps density at the Si/SiO2 interface. Si PIN diodes were fabricated, by considering all the important aspects discussed in this paper, and consequently an excellent spectral response was observed.

PIN diodes for radiation therapy use: Their construction, characterization, and implementation

PurposeDevelopment and implementation of a PIN diode measurement system that can measure dose on the surface of a patient, which can be compared to dose calculated by a treatment planning system. Measurements are to be possible for static or rotational photon beams and electrons. Simple calibration procedures are to be devised that require a minimum set of correction factors. MethodsReadily available PIN type photodiodes are fabricated into devices that can be used for detection of ionizing radiation. Single or dual PIN diodes are soldered onto flexible shielded cables for static and rotational irradiation use. Diode signals are measured with an electrometer with zero input bias voltage. Diode temperature is determined by operating it as a thermistor. Linac photon and electron dose is measured. A commercial treatment planning system is used for calculating dose expected in various test geometries. ResultsThe scanning and surface diodes have an intrinsic buildup of 0.3 mm water equivalence and the IMRT device a buildup of 1.5 mm. Correction factors are determined for changes in diode sensitivity with the following factors: dose-per-pulse, dose rate, angle of radiation incidence, temperature, and field size. The surface or IMRT diode detector measurements agree within 1.0% with Eclipse calculations. ConclusionsClinically useable dose detection devices can be fabricated from PIN type photodiodes. These diodes are used to measure dose at the surface of a patient or under bolus. Correction factors are unnecessary if a surface or IMRT type device is chosen for use with static orthogonal or rotational IMRT delivered beams, respectively.

Conceptual design of stacked-layer detectors to increase the sensitivity of Fast Neutron Gamma-ray Radiography (FNGR)

This study is focused on the structure and other possible factors related to scintillators used in the Fast Neutron and Gamma-ray Radiography (FNGR) system to increase its sensitivity. The CsI(Tl) crystal scintillator (Co-60 gamma-ray detection) and the BC430 plastic scintillator (14 MeV fast neutron detection) were analyzed with the Monte Carlo simulation (MCNPX and DETEC97 codes). Each scintillator was investigated with regard to the optimum thickness (1 cm × 1 cm), reconfiguration of detector modules (a stacked-layer structure), the optimum surface treatment, and the spectral matching with customized PIN-type photodiodes. As a result, the optimum thickness of the CsI(Tl) was found to be 4.5 cm; the optimum value was 5.5 cm for the BC430. When the detector modules were stacked in a sandwich structure rather than the existing single detector structure, the light photon transmission to the surface of the photodiode was enhanced by 40% and 58% for CsI(Tl) and BC430, respectively. In the matter of scintillator surface treatment, both scintillators were simulated with unpolished and polished condition before coating. The polished condition of the scintillator surfaces showed a higher performance, more than doubling that of the unpolished condition surfaces. Then, the performance improvement of the scintillator with the paint coating was compared to the scintillator with the metal coating conditions. For CsI(Tl), the metal coating showed a 10 % higher performance than that of the paint coating, and the metal coating of BC430 showed a 6% higher performance than that of the paint coating. As a result of spectral matching between the scintillators and the customized PIN-photodiodes, PS100-6b of Silicon AG, SD445-14-21-305 of API, and FSD1010-CAL of THOLABS were compared. The spectral matching factor of PS100-6b was 0.39 with CsI(Tl) and was 0.42 with BC430; the spectral matching factors of the other samples were relatively lower (SD445-14-21-305 with CsI(Tl): 0.29; SD445-14-21-305 with BC430: 0.33; FSD1010-CAL with CsI(Tl): 0.26; FSD1010-CAL with BC430: 0.29).

Development of a portable X-ray scan system (PXSS)

Using a linear array detector module, we have developed a portable X-ray scan system of 430( L)×62( W)×35( H) mm 3. The system is a battery-powered portable X-ray scan system that offers a maximum scan speed of 44 cms −1. The scanner module consists of a phosphor screen of Lanex regular TM coupled with linear array photodiodes of 0.1 kΩ cm and front-end electronics based on discrete charge-sensitive preamplifiers (C-amp). To derive the optimum performance of the X-ray scanner, the key components, including its PIN-type photodiode, feedback capacitor and resistor in C-amps, were investigated in terms of electronics and radiation responses. With an optimum combination of key components, the system showed a dynamic range of about 3500 and an image lag of 1 at a maximum scan speed in the X-ray condition of 100 kV/3 mA.

Autocorrelation and phase retrieval in the UV using two-photon absorption in diamond pin photodiodes

We report on the utilization of the two-photon induced free carrier generation in a diamond pin-type photodiode to record fringe-resolved second-order autocorrelations of femtosecond pulses in the UV. Measurements in photovoltaic mode are performed at the second and third harmonic of a Ti:sapphire laser (lambda(0)=401 nm and lambda(0)=265 nm) with pulse energies down to about 2 nJ. The band gap of diamond of 5.5 eV sets a short wavelength limit at about 225 nm. Combined with the simultaneously recorded linear autocorrelation the spectral phase is reconstructed employing an iterative algorithm.

Portable gamma-ray tracking system for nuclear material safety

Using a CsI (Tl)-coupled PIN-type photodiode of 1 cm×1 cm and compact data acquisition system, a portable gamma monitoring system with lower cost has been fabricated and tested for gamma detection. After evaluating spectroscopy performance for gamma emission radioisotopes of Co-57 and Cs-137, we integrated the DAS with low-noise preamplifier, shaping amplifier, discriminator and multi-control unit (MCU) to acquire cumulative gamma detection data. The data are continuously sent to an observer, through a wireless telecommunication module of 400 MHz band, to monitor whether any gamma emitting material is out of sight or any accident takes place. A comparative study of gamma spectroscopy between our detector and a commercialized detector has been performed.

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.

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.

Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography

Using 5 cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1 cm×1 cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for both Co-60 and Cs-137 gamma sources. The first detector showed energy resolutions (FWHM) of 6.4% and 5.5% for 1.17 and 1.33 MeV, which were similar to energy resolutions of the second detector for Co-60, but the second detector showed 6.6% better resolution than the first detector's 11.8% for Cs-137. For 10 h exposure of Co-60 (14.5 μCi), noise equivalent quanta (NEQ) and spectroscopy for both detectors have been investigated in detail. The NEQ of 25% increased after the exposure and degradations of the FWHMs of 26% and 11% have been found for 1.17 and 1.33 MeV, respectively.

Ceramic scintillator-coupled linear array PIN photodiode for X-ray scanner

In order to design the full system of dual-energy X-ray scanner, each component of the system has been fabricated and tested. The high-energy X-ray detector modules used a ceramic scintillator of Eu 3+-doped (Gd,Y) 2O 3, manufactured using Glycine Nitrate Process (GNP). This was coupled to a 16-channel linear array PIN-type photodiode. The low-energy module was a commercially available Lanex Regular screen that was also coupled to a 16-channel linear array PIN-type photodiode. The 16-channel linear array PIN-type photodiode of 1.5 mm×3.2 mm was fabricated in the process of Electronics and Telecommunications Research Institute (ETRI). With a data acquisition system, signal-to-noise ratio was measured at low X-ray energy and low photon flux to evaluate each scintillator-coupled detector module. Through the experiment results and analysis, we inspected each component of the system as a dual-energy single-exposure X-ray scanner.

Design of pixellated scintillator on PIN-type photodiode for digital mammography

We tested the system resolution of the FOS-CsI (Tl) coupled to CMOS APS for mammography of 28 kV p. Through the results, this detector showed 14 cycle/mm at zero MTF. The reason it was showing lower resolution than was expected was analyzed using the characteristics of scintillator and sensor. The estimation method of system resolution using the ratio of dark current and photocurrent was derived. The resolution of the candidate detectors and conceptual design of pixellated 2-D sensor array performance were investigated through this method. One of the candidate detectors showed desirable resolution of over 20 cycle/mm.

Design of an improved neutron dose equivalent dosimeter

This paper describes the design and development of a new active area neutron dosimeter. The design incorporates a traditional central detector with a moderator/filter arrangement and a number of outer PIN type photodiodes sensitised to thermal neutrons by the application of a lithium fluoride converter. The outer thermal detectors allow the determination of the neutron radiation field characteristics. The experimental programme has demonstrated that such an arrangement is capable of discriminating between various neutron fields and the usefulness of MCNP4b as a design tool.