Si PIN Research Articles

In situ analysis of carrier lifetime and barrier capacitance variations in silicon during 1.5 MeV protons implantation

Results of the in situ measurements of the recombination lifetime and of barrier capacitance variations in Si substrates and pin diodes, respectively, during 1.5 MeV protons implantation are presented. Carrier recombination lifetime has been measured by employing microwave probed photoconductivity method, while parameters of the barrier capacitance changes have been extracted by transient technique of barrier capacitance charging current measurements using linearly increasing voltage pulses. Sub-linear decrease of carrier lifetime as a function of fluence has been revealed and peculiarities of such characteristic are explained in terms of formation of two layered structure within implanted Si material. Carrier recombination processes determine the increase of dielectric relaxation time within electrically neutral region (ENR) of a diode base. Carrier capture/emission processes within space charge (SC) and transition layer (between ENR and SC) regions lead to increase of generation/recombination currents in the irradiated diode.

Performance test of Si PIN photodiode line scanner for thermal neutron detection

Abstract Thermal neutron imaging using Si PIN photodiode line scanner and Eu-doped LiCaAlF6 crystal scintillator has been developed. The pixel dimensions of photodiode are 1.18 mm (width)×3.8 mm (length) with 0.4 mm gap and the module has 192 channels in linear array. The emission peaks of Eu-doped LiCaAlF6 after thermal neutron excitation are placed at 370 and 590 nm, and the corresponding photon sensitivities of photodiode are 0.04 and 0.34 A/W, respectively. Polished scintillator blocks with a size of 1.18 mm (width)×3.8 mm (length)×5.0 mm (thickness) were wrapped by several layers of Teflon tapes as a reflector and optically coupled to the photodiodes by silicone grease. JRR-3 MUSASI beam line emitting 13.5 meV thermal neutrons with the flux of 8×105 n/cm2 s was used for the imaging test. As a subject for imaging, a Cd plate was moved at the speed of 50 mm/s perpendicular to the thermal neutron beam. Analog integration time was set to be 416.6 μs, then signals were converted by a delta–sigma A/D converter. After the image processing, we successfully obtained moving Cd plate image under thermal neutron irradiation using PIN photodiode line scanner coupled with Eu-doped LiCaAlF6 scintillator.

Impact of generation current on the evaluation of the depletion width in heavily irradiated Si detectors

The depletion width and full depletion condition are essential parameters in the search for radiation tolerant detector design and operational regimes. In this work, results of measurements of barrier capacitance by combining a transient technique for barrier evaluation by linearly increasing voltage (BELIV), with temperature dependent capacitance-voltage and current-voltage characteristics of neutron irradiated Si pin detectors are discussed. It is shown that the generation current, caused by a high density of radiation induced traps, distorts the capacitance measurements in heavily irradiated devices. There is no space charge sign inversion effect, however, and heavily irradiated detectors become fully depleted in equilibrium.

A new mini gas ionization chamber for IBA applications

Novel prototypes of high resolution gas ionization chambers ( GIC) were designed with increased compactness and simplicity of the setup. They have no Frisch-grid and a simple anode wire. Under certain operating conditions these mini detectors have an energy resolution comparable with that of state-of-the-art GICs of much higher complexity. They can be operated both under vacuum and atmospheric pressure. First measurements were made with protons in the energy range of 0.3–1.0 MeV. For protons at 0.3 MeV an energy resolution of about 12 keV was achieved. With a 72 MeV 129Xe beam a relative resolution of 1.4% was obtained. Due to their versatility and reduced size the detectors can easily be applied in the field of ion beam analysis ( IBA) and accelerator mass spectrometry ( AMS) . Since they are almost completely insensitive to radiation damage they are especially suited for use in high fluence applications such as scanning transmission ion microscopy ( STIM). A comparison of the radiation hardness of the mini GIC with a Si PIN diode was therefore performed. The GIC showed no peak shift or change in energy resolution at all after collecting 10 15 protons per cm 2 while the performance of the Si detector clearly started to degrade at 10 12 particles per cm 2.

Si PIN X-ray photon counter

A Si PIN detector for visible light detection, instead of a Geiger-Muller tube, is applied to X-ray photon counting. We counted radiation from a checking source of a Geiger-Muller counter with a Si PIN counter and with a Geiger-Muller counter. White X-ray of energy up to 20 keV emitted from a pyroelectric X-ray emitter was also counted, and the Si PIN X-ray counter showed a similar curve of count rate versus source distance in both measurements. Pulse counting was performed by spectroscopy circuits. An audio digitizer with computer software for signal processing was also used to simplify the photon counter. A plot of count rate versus time was obtained with this setup. With simple pulse counting circuits, Si PIN X-ray counters have advantages such as compact structure, low cost and easy application. Copyright © 2011 John Wiley & Sons, Ltd.

Precision measurements of theCo60β-asymmetry parameter in search for tensor currents in weak interactions

The $\beta$-asymmetry parameter $\widetilde{A}$ for the Gamow-Teller decay of $^{60}$Co was measured by polarizing the radioactive nuclei with the brute force low-temperature nuclear-orientation method. The $^{60}$Co activity was cooled down to milliKelvin temperatures in a $^3$He-$^4$He dilution refrigerator in an external 13 T magnetic field. The $\beta$ particles were observed by a 500 ${\mu}m$ thick Si PIN diode operating at a temperature of about 10 K in a magnetic field of 0.6 T. Extensive GEANT4 Monte-Carlo simulations were performed to gain control over the systematic effects. Our result, $\widetilde{A} = -1.014(12)_{stat}(16)_{syst}$, is in agreement with the Standard-Model value of $-0.987(9)$, which includes recoil-order corrections that were addressed for the first time for this isotope. Further, it enables limits to be placed on possible tensor-type charged weak currents as well as other physics beyond the Standard Model.

An iterative method applied to optimize the design of PIN photodiodes for enhanced radiation tolerance and maximum light response

An iterative method based on numerical simulations was developed to enhance the proton radiation tolerance and the responsivity of Si PIN photodiodes. The method allows to calculate the optimal values of the intrinsic layer thickness and the incident light wavelength, in function of the light intensity and the maximum proton fluence to be supported by the device. These results minimize the effects of radiation on the total reverse current of the photodiode and maximize its response to light. The implementation of the method is useful in the design of devices whose operation point should not suffer variations due to radiation.

Evidence of decay of flux ratio of Fe to Fe-Ni line features with electron temperature in solar flares

We report observational evidence of the decay of the flux ratio of Fe to Fe-Ni line features as a function of plasma electron temperature in solar flares in comparison to that theoretically predicted by Phillips (2004). We present the study of spectral analysis of 14 flares observed by the Solar X-ray Spectrometer (SOXS) — Low Energy Detector (SLD) payload. The SLD payload employs the state-of-the-art solid state detectors, viz., Si PIN and Cadmium-Zinc-Telluride (CZT) devices. The sub-keV energy resolution of Si PIN detector allows us to study the Fe-line and Fe-Ni line features appearing at 6.7 and 8 keV, respectively, in greater detail. In order to best-fit the whole spectrum at one time in the desired energy range between 4 and 25 keV we considered Gaussian-line, the multi-thermal power-law and broken power-law functions. We found that the flux ratio of Fe to Fe-Ni line features decays with flare electron temperature by the asymptotic form of polynomial of inverse third order. The relative flux ratio is ∼30 at temperature 12 MK which drops to half, ∼15 at 20 MK, and at further higher temperatures it decreases smoothly reaching to ∼8 at ∼50 MK. The flux ratio, however, at a given flare plasma temperature, and its decrease with temperature is significantly lower than that predicted theoretically. We propose that the difference may be due to the consideration of higher densities of Fe and Fe-Ni lines in the theoretical model of Phillips (2004). We suggest revising the Fe and Fe-Ni line densities in the corona. The decay of flux ratio explains the variation of equivalent width and peak energy of these line features with temperature.

Feasibility of spectro-photometry in X-rays (SPHINX) from the moon

Doing space Astronomy on lunar surface has several advantages. We present here feasibility of an All Sky Monitoring Payload for Spectro-photometry in X-rays (SPHINX) which can be placed on a lander on the moon or in a space craft orbiting around the moon. The Si–PIN photo-diodes and CdTe crystals are used to detect solar flares, bright gamma bursts, soft gamma-ray repeaters from space and also X-ray fluorescence (XRF) from lunar surface. We present the complete Geant4 simulation to study the feasibility of such an instrument in presence of Cosmic Diffused X-Ray Background (CDXRB). We find that the signal to noise ratio is sufficient for moderate to bright GRBs (above 5 keV), for the quiet sun (up to 100 keV), solar flares, soft gamma-ray repeaters, X-ray Fluorescence (XRF) of lunar surface etc. This is a low-cost system which is capable of performing multiple tasks while stationed at the natural satellite of our planet.

Characteristics of a Fabricated PIN Photodiode for a Matching With a CsI(Tl) Scintillator

Recently a PIN photodiode is more widely used than a conventional PMT, because it requires less bias to operate it and it is very compact. A PIN photodiode was designed and fabricated for a matching with a CsI(Tl) scintillator in consideration of low leakage current and high biasing voltage. Leakage current and spectral response were measured with the fabricated PIN photodiode as preliminary tests. A CsI(Tl)/PIN photodiode radiation detector was also fabricated and about 10.4% FWHM was achieved at 662 keV gamma-ray. In this study, characteristics of a fabricated PIN photodiode and a CsI(Tl)/PIN photodiode radiation detector were presented. Several important aspects to consider in the fabrication of a Si PIN photodiode radiation detector are also addressed.

Radiation hardness of optoelectronic components for the optical readout of the ATLAS inner detector

Optical links are used for data transmission of the ATLAS inner detector in a radiation hazard environment at the Large Hadron Collider (LHC). The radiation tolerance is studied for the opto-electronics of GaAs VCSEL and epitaxial Si PIN with 30 and 70 MeV protons at CYRIC. High speed Si and GaAs PIN photo-diodes are also investigated for upgrade to super-LHC. The annealing of GaAs VCSEL by charge injection is characterized. The GaAs devices show approximately linear degradations to fluence. The dependence on proton energy is compared to the Non-Ionizing Energy Loss calculations.

Tailoring a plasma focus as hard x-ray source for imaging

An investigation on temporal and spatial properties of hard x-rays (15–88 keV) emitted in a 5.3 kJ plasma focus using Si pin diodes and a pinhole camera is reported. The maximum yield of hard x-rays of 15–88 keV range is estimated about 4.7 J and corresponding efficiency for x-ray generation is 0.09%. The x-rays with energy >15 keV have 15–20 ns pulse duration and ∼1 mm source size. This radiation is used for contact x-ray imaging of biological and compound objects and spatial resolution of ∼50 μm is demonstrated.

用于高能X光测量的Si-PIN阵列探测器

One-dimensional little-area Si PIN detectors array for high energy X-ray measurement was developed. The sensitivity, linear output current and time response of the Si PIN were calculated theoretically and also simulated using MC software EGSnrc. According to the theoretical study, little-area Si PIN detectors array can be used to detect high intensity and high energy X-ray with better spatio-temporal resolution(3 mm-8 ns). Primary experiments were carried out based on the theoretical design on “Dragon-Ⅰ” linear induction electron accelerator using the Si-PIN photoelectric cell and the corresponding amplifier. Rreasonable response of Si-PIN photoelectric cell was gained for optimum design of practical one-dimensional little-area Si PIN detectors array.

Dependence of silicon PIN diode electrical characteristics on proton fluence

A comparative analysis of capacitance–voltage (C–V ) and current–voltage (I–V ) characteristics dependent on proton irradiation fluence in the range from 7·1012 to 7·1014 p/cm2 has been performed in float zone (FZ) silicon PIN diodes. A δ-shape and triangle profiles of radiation induced defects were formed by irradiation with protons having energy in the range from 2.0 to 2.7 MeV. Temperature-dependent variations of current (I–T) at fixed reverse voltage VR enable one to extract the thermal activation parameters. These values are found to be in a quantitative agreement with trap activation parameters measured by DLTS technique. The role of point and extended defects in correlated modifications of C–V and I–V characteristics of the irradiated diodes is discussed. Keywords: radiation defects, Si PIN diodes, capacitance–voltage, current–voltage characteristics

Investigation of the switching and carrier recombination characteristics in the proton irradiated and thermally annealed Si PIN diodes

Results of comparative study of deep level transient spectroscopy and of reverse recovery time (RR) of PIN diodes with δ-and triangle-shape radiation defect distribution profiles are presented. FZ silicon PIN diodes were irradiated by varying proton fluence in the range of 1013–1015 p/cm2 and keeping fixed or gradually changing protons energy in the range of 2–2.7 MeV to introduce different profiles of radiation defects. Variations of the functional characteristics of PIN diodes containing different density of radiation defects and their distribution profiles are compared. Isochronous 24 h annealings in the temperature range of 80–400°C have been performed in order to suppress the detrimental carrier generation centres Keywords: reverse recovery time, deep level transient spectroscopy, radiation defects, carrier lifetime, Si PIN diodes

Numerical Simulations of Pillar Structured Solid State Thermal Neutron Detector: Efficiency and Gamma Discrimination

This paper reports numerical simulations of a three-dimensionally integrated, Boron-10 (10B) and Silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and 7Li) created from the neutron-10B reaction. In this paper, the effect of both the 3-D geometry (including pillar width, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the experimental data available at this time, for 7- and 12-mum tall micropillar arrays. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.

Enhancing soft X-ray emission with depleted uranium in neon plasma focus

Depleted uranium (U 238 ) is used for pre-ionization in the neon gas to study the soft X-ray emission in a Mather type plasma focus of 3.3 kJ. The X-rays are detected using an assembly of Quantrad Si pin diodes, masked with differential Ross fitters, and with a multi pinhole camera. The X-ray yield and pinhole images are found strongly influenced by the preionization and the pressure of the working gas. The soft X-ray yield of 82.5 ± 4.0 J in 1.3-1.56 keV energy window is obtained in the case of preionization of neon gas at the optimum pressure of 5 mbar, leading to the conversion efficiency of 2.5% of the stored energy. The total yield with preionization is 195 ± 9.0 J in 4π geometry measured at the optimum pressure of 5 mbar giving conversion efficiency of 5.9%. The time integrated images indicate the broadening of X-ray emission zone with preionization.

Transient current mapping obtained from silicon photodiodes using focused ion microbeams with several hundreds of MeV

Single Event Effects (SEEs) triggered by energetic heavy ions traversing a sensitive parts of electric devices have been studied using high-energy heavy ion microbeams connected with Transient Ion Beam Induced Current (TIBIC) measuring system at the Japan Atomic Energy Agency (JAEA) Takasaki Ion Accelerators for Advanced Radiation Applications (TIARA) facility. In the TIBIC system, SEE for semiconductor device, that is fast charge collection, has been observed in timescales of the order of picoseconds. In this paper, we show successful demonstration of the performance of the system, in which clear images of TIBIC map have been observed for Si pin photodiodes irradiated by 260 MeV 20Ne 7+ and also by 520 MeV 40Ar 14+ microbeams.

Uso da fluorescência de raios X portátil (XRF) in vivo como técnica alternativa para acompanhamento dos níveis de ferro em pacientes com sobrecarga de ferro

Foi investigada a viabilidade da aplicação da técnica de fluorescência de raios X (XRF) como alternativa para acompanhamento dos níveis de ferro em pacientes portadores de talassemia maior (beta-thalassemia) e hemocromatose hereditária (HH). As medidas foram realizadas no Hemocentro do Hospital Universitário e no Laboratório de Física Nuclear Aplicada da Universidade Estadual de Londrina. Foi acompanhada uma portadora de talassemia maior e quatro pessoas sadias. Foi utilizado um sistema portátil de XRF constituído de uma fonte de Raios X de 238Pu e um detector de SiPIN diodo, para as medidas in vivo na mão. O sistema foi calibrado medindo simulados de solução aquosa com 15 a 150 ppm de ferro. A duração de cada medida foi de 50 s. O limite de detecção (LLD) atingido foi de 13 ppm de ferro. A dose de radiação na pele foi de 10 mSv. A paciente de talassemia apresentou 74 ± 6 ppm de ferro, enquanto pessoas sadias apresentaram valor médio de 53 ± 5 ppm de ferro. Os resultados estão de acordo com a literatura, que informa níveis de ferro na pele de 15 a 60 ppm em pessoas sadias e de 70 a 150 ppm em pacientes portadores da talassemia maior. Foi concluído ser viável a aplicação da XRF para acompanhamento de pacientes de talassemia maior e HH.

High-Speed Response Si PIN Photodetector Fabricated and Studied for Visible and Near Infrared Spectral Detection

High-Speed Response Si PIN Photodetector Fabricated and Studied for Visible and Near Infrared Spectral Detection