Silicon On Insulator Detector Research Articles

Simulation study on SOI based electron tracking Compton camera using deep learning method

Compton imaging is a promising method of sub MeV to a few MeV gamma-rays and expected to use in various application field, such as medical imaging, environmental monitoring and astrophysics. Several types of Compton camera has beed developed using different materials. One of the drawbacks in conventional Compton imaging is relatively low signal to background ratio caused by its projected Compton cones. Recoil electron tracking is one straight-forward way to improve the signal-to-background ratio, however, it is only realized in gaseous detectors. The realization of electron tracking in solid detectors is under investigation because of its short track in scatter materials. We demonstrated the capability of electron tracking in silicon-on-insulator (SOI) pixel detector with 30 μm pixels size. The extraction of ejected direction of recoil electrons in Compton scattering is an important problem. In this work, we investigated the use of deep learning for estimating the angle in plane and depth using Geant 4 Monte Carlo simulation. The effect of pixel size to the estimation accuracy and SPD is characterized for the application of actual silicon-on-insulator based SOI detectors. The imaging capability is also characterized using predicted recoil electron direction.

Development of integration-type silicon-on-insulator monolithic pixel detectors using a float zone silicon

In this paper, we describe the development of monolithic pixel detectors using silicon-on-insulator (SOI) technology for a rapid X-ray residual stress measurement system. Conventional two-dimensional X-ray detectors are not suitable for rapid X-ray residual stress measurement because of their large pixel size and slow readout. For this reason, we developed highly sensitive SOI monolithic pixel detectors that are made up of smaller pixels and can provide a more rapid X-ray residual stress measurement readout. The detectors are fabricated using a 0.2μm CMOS fully-depleted SOI process (Lapis Semiconductor Co., Ltd). The SOI wafer is made by directly bonding a thick, high-resistivity Si wafer and a low-resistivity Si CMOS wafer. The process does not make use of mechanical bump bonding. We developed an integration-type SOI pixel detector, INTPIX4, for a rapid X-ray residual stress measurement system; it uses a float zone (FZ) or Czochralski (Cz) silicon wafer. Cz SOI detectors have been in use since 2005. After 2011, FZ SOI detectors were successfully fabricated. In this paper, we state recent progresses and test results of the SOI monolithic pixel detector using a FZ silicon and compare them with the results obtained using the Cz detector.

Test-beam results of a SOI pixel-detector prototype

This paper presents the test-beam results of a monolithic pixel-detector prototype fabricated in 200nm Silicon-On-Insulator (SOI) CMOS technology. The SOI detector was tested at the CERN SPS H6 beam line. The detector is fabricated on a 500 μm thick high-resistivity float-zone n-type (FZ-n) wafer. The pixel size is 30 μm × 30 μm and its readout uses a source-follower configuration. The test-beam data are analysed in order to compute the spatial resolution and detector efficiency. The analysis chain includes pedestal and noise calculation, cluster reconstruction, as well as alignment and η-correction for non-linear charge sharing. The results show a spatial resolution of about 4.3 μm.

Radiation Imaging Detectors Using SOI Technology

Silicon-on-Insulator (SOI) technology is widely used in high-performance and low-power semiconductor devices. The SOI wafers have two layers of active silicon (Si), and normally the bottom Si layer is a mere physical structure. The idea of making intelligent pixel detectors by using the bottom Si layer as sensors for X-ray, infrared light, high-energy particles, neutrons, etc. emerged from very early days of the SOI technology. However, there have been several difficult issues with fabricating such detectors and they have not become very popular until recently. This book offers a comprehensive overview of the basic concepts and research issues of SOI radiation image detectors. It introduces basic issues to implement the SOI detector and presents how to solve these issues. It also reveals fundamental techniques, improvement of radiation tolerance, applications, and examples of the detectors. Since the SOI detector has both a thick sensing region and CMOS transistors in a monolithic die, many ideas have emerged to utilize this technology. This book is a good introduction for people who want to develop or use SOI detectors.

Development of electron-tracking Compton imaging system with 30-μm SOI pixel sensor

Compton imaging is a useful method to localize gamma sources without using mechanical collimators. In conventional Compton imaging, the incident directions of gamma rays are estimated in a cone for each event by analyzing the sequence of interactions of each gamma ray followed by Compton kinematics. Since the information of the ejection directions of the recoil electrons is lost, many artifacts in the shape of cone traces are generated, which reduces signal-to-noise ratio (SNR) and angular resolution. We have developed an advanced Compton imaging system with the capability of tracking recoil electrons by using a combination of a trigger-mode silicon-on-insulator (SOI) pixel detector and a GAGG detector. This system covers the 660–1330 keV energy range for localization of contamination nuclides such as 137Cs and 134Cs inside the Fukushima Daiichi Nuclear Power Plant in Japan. The ejection directions of recoil electrons caused by Compton scattering are detected on the micro-pixelated SOI detector, which can theoretically be used to determine the incident directions of the gamma rays in a line for each event and can reduce the appearance of artifacts. We obtained 2-D reconstructed images from the first iteration of the proposed system for 137Cs, and the SNR and angular resolution were enhanced compared with those of conventional Compton imaging systems.

Test of a fine pitch SOI pixel detector with laser beam**Supported by National Natural Science Foundation of China (11375226)

A silicon pixel detector with fine pitch size of 19 μm × 19 μm, developed based on SOI (silicon-on-insulator) technology, was tested under the illumination of infrared laser pulses. As an alternative method for particle beam tests, the laser pulses were tuned to very short duration and small transverse profile to simulate the tracks of MIPs (minimum ionization particles) in silicon. Hit cluster sizes were measured with focused laser pulses propagating through the SOI detector perpendicular to its surface and most of the induced charge was found to be collected inside the seed pixel. For the first time, the signal amplitude as a function of the applied bias voltage was measured for this SOI detector, deepening understanding of its depletion characteristics.

Novel detectors for silicon based microdosimetry, their concepts and applications

This paper presents an overview of the development of semiconductor microdosimetry and the most current (state-of-the-art) Silicon on Insulator (SOI) detectors for microdosimetry based mainly on research and development carried out at the Centre for Medical Radiation Physics (CMRP) at the University of Wollongong with collaborators over the last 18 years. In this paper every generation of CMRP SOI microdosimeters, including their fabrication, design, and electrical and charge collection characterisation are presented. A study of SOI microdosimeters in various radiation fields has demonstrated that under appropriate geometrical scaling, the response of SOI detectors with the well-known geometry of microscopically sensitive volumes will record the energy deposition spectra representative of tissue cells of an equivalent shape. This development of SOI detectors for microdosimetry with increased complexity has improved the definition of microscopic sensitive volume (SV), which is modelling the deposition of ionising energy in a biological cell, that are led from planar to 3D SOI detectors with an array of segmented microscopic 3D SVs. The monolithic ΔE−E silicon telescope, which is an alternative to the SOI silicon microdosimeter, is presented, and as an example, applications of SOI detectors and ΔE−E monolithic telescope for microdosimetery in proton therapy field and equivalent neutron dose measurements out of field are also presented. An SOI microdosimeter “bridge” with 3D SVs can derive the relative biological effectiveness (RBE) in 12C ion radiation therapy that matches the tissue equivalent proportional counter (TEPC) quite well, but with outstanding spatial resolution. The use of SOI technology in experimental microdosimetry offers simplicity (no gas system or HV supply), high spatial resolution, low cost, high count rates, and the possibility of integrating the system onto a single device with other types of detectors.

X-ray generation by inverse Compton scattering at the superconducting RF test facility

Quasi-monochromatic X-rays with high brightness have a broad range of applications in fields such as life sciences, bio-, medical applications, and microlithography. One method for generating such X-rays is via inverse Compton scattering (ICS). X-ray generation experiments using ICS were carried out at the superconducting RF test facility (STF) accelerator at KEK. A new beam line, newly developed four-mirror optical cavity system, and new X-ray detector system were prepared for experiments downstream section of the STF electron accelerator. Amplified pulsed photons were accumulated into a four-mirror optical cavity and collided with an incoming 40MeV electron beam. The generated X-rays were detected using a microchannel plate (MCP) detector for X-ray yield measurements and a new silicon-on-insulator (SOI) detector system for energy measurements. The detected X-ray yield by the MCP detector was 1756.8±272.2 photons/(244 electron bunches). To extrapolate this result to 1ms train length under 5Hz operations, 4.60×105 photons/1%-bandwidth were obtained. The peak X-ray energy, which was confirmed by the SOI detector, was 29keV, and this is consistent with ICS X-rays.

Development of the Pixel OR SOI detector for high energy physics experiments

A Silicon-On-Insulator (SOI) Technology is suitable for vertex detectors for high energy physics experiments since complex functions can be fabricated on the SOI wafer with a small amount of material thanks to the monolithic structure. We developed a new sensor processing scheme “PIXOR(PIXel OR)” for pixel detectors using a LAPIS 0.20μm SOI process.An analog signal from each pixelated sensor is divided into two dimensional directions, and 2n signal channels from a small n by n pixel matrix are ORed as n column and n row channels, then the signals are processed by a readout circuit in each small matrix. This PIXOR scheme reduces the number of readout channels and avoids a deterioration of intrinsic position resolution due to large circuit area, that was a common issue for monolithic detectors. This feature allows high resolution, low occupancy and on-sensor signal processing at the same time. We present the successful results of the PIXOR readout scheme using a first prototype.

Performance study of SOI monolithic pixel detectors for X-ray application

We are now developing Silicon-on-insulator (SOI) monolithic pixel detectors for X-ray and charged particle applications in collaboration with OKI Semiconductor Co., Ltd. The detector development project started in 2005 and the SOI process for pixel detectors was developed. We developed some prototypes of SOI pixel detectors. Specifically, integration type and counting type pixel detectors were irradiated with a continuous red laser, infrared laser and X-rays and their performances were studied. One of the issues in the SOI detectors is the back-gate effect, that is, higher back bias voltages affect the characteristics of SOI-CMOS transistors. As a result of the new process step to protect the device against the back-gate effect, images with higher back bias voltages were obtained in the integration-type pixel detector. We also confirmed the dependence on 8 keV X-ray intensity for the counting type pixel detector. In 2009, new versions of the detectors were designed to improve their performances with X-rays and charged particles.

Development of monolithic active pixel detector in SOI technology

A novel solution of an active pixel detector, which exploits wafer-bonded Silicon on Insulator (SOI) substrates for integration of the readout electronics with the pixel detector, is presented. The main concepts of the proposed monolithic sensor and the preliminary tests results with ionising radiation sources are addressed. SOI is an alternative solution of a monolithic active pixel detector, which allows integrating fully depleted sensor and front-end electronics active layers into one silicon wafer. The main idea of the sensor relies on the use of both the monolithic silicon layers (device and support layers) of the SOI substrate for fabrication of pixel detector diodes and readout electronics. Such detectors can find a wide range of applications, not only in particle physics but also in medicine, space science and many other disciplines. The sensor structure and the readout configuration have been developed and the measurements of a dedicated test structure have validated the new technology of the SOI detector. Then small SOI sensor matrices with 8×8 channels have been recently produced and tested.

SOI NMOSFET을 이용한 Photo Detector의 특성

In this paper, a new Silicon on Insulator (SOI)-based photodetector was proposed, and its basic operation principle was explained. Fabrication steps of the detector are compatible with those of conventional SOI CMOS technology. With the proposed structure, RGB (Read, Green, Blue) which are three primary colors of light can be realized without using any organic color filters. It was shown that the characteristics of the SOI-based detector are better than those of bulk-based detector. To see the response characteristics to the green (G) among RGB, SOI and bulk NMOSFETS were fabricated using <TEX>$1.5\mu m$</TEX> CMOS technology and characterized. We obtained optimum optical response characteristics at <TEX>$V_{GS}=0.35 V$</TEX> in NMOSFET with threshold voltage of 0.72 V. Drain bias should be less than about 1.5 V to avoid any problem from floating body effect, since the body of the SOI NMOSFET was floated. The SOI and the bulk NMOSFETS shown maximum drain currents at the wavelengths of incident light around 550 nm and 750 nm, respectively. Therefore the SOI detector is more suitable for the G color detector.