In our previous work on ultra-fast silicon detectors, extremely small carrier drift times of 50–100 picoseconds were predicted for electrode spacing of 5–10 μm. Expanding on these previous works, we systematically study the electrical characteristics of the ultra-fast, 3D-trench electrode silicon detector cell with p-type bulk silicon, such as electric potential distribution, electric field distribution, hole concentration distribution, and leakage current to analyze the full detector depletion voltage and other detector properties. To verify the prediction of ultra-fast response times, we simulate the instant induced current curves before and after irradiation with different minimum ionizing particle (MIP) hitting positions. High position resolution pixel detectors can be fabricated by constructing an array of these extremely small detector cells.

Silicon avalanche photodetector (APD) plays a very important role in near-infrared light detection due to its linear controllable gain and attractive manufacturing cost. In this paper, a silicon APD with punch-through structure is designed and fabricated by standard 0.5 μm complementary metal oxide semiconductor (CMOS) technology. The proposed structure eliminates the requirements for wafer-thinning and the double-side metallization process by most commercial Si APD products. The fabricated device shows very low level dark current of several tens Picoamperes and ultra-high multiplication gain of ~4600 at near-infrared wavelength. The ultra-low extracted temperature coefficient of the breakdown voltage is 0.077 V/K. The high performance provides a promising solution for near-infrared weak light detection.

In this work, one-dimensional (1D) modeling and simulations of the electric and weighting fields will be systematically carried out for hypothetical sphere-electrode detectors. Exact 1D solutions are obtained for electric and weighting fields in these detectors. Although it is impossible to realize hypothetical sphere-electrode detectors with current technologies, the theoretical work and results on them are good bases for their offspring—practical semi-sphere-electrodes (semisph-electrode) and near-semisph-electrode detectors. The great reduction in full depletion voltage and small capacitance in semisph-electrode and near-semisph-electrode detectors make them very good for applications in photon sciences (x-ray) and safeguard and homeland security (hard x-ray and gamma-ray). A practical novel structure of the three-dimensional (3D) trench electrode detector, namely a novel semisph-electrode silicon detector has been proposed as a practical example. The novel detector has a semispherical shell electrode created in a cuboidal unit cell. It will overcome the traditional 3D-electrode detector deficiencies in electrical performance such as the asymmetrical electric field distribution. Through a computer-aided design tool, 3D modeling and electrical characteristics, simulation of a semispherical electrode silicon detector has been obtained, such as electric field distributions, electron concentration distribution, and full depletion voltage

An X-ray pulsar is a remnant of massive star evolution, collapse, and supernova explosions. It has an extremely stable spin cycle and is known as the most accurate astronomical clock in the natural world. It presents high-precision navigational information, such as the location, speed, time, and attitude, which are used in deep space exploration and interstellar flight, such as the X-ray pulsar navigation (XPNAV). However, the energy of the X-ray from the pulsar is very low and its signal is very weak; this X-ray is known as the soft X-ray. In the low and medium energy radiation spectroscopy, the semiconductor detectors, especially the silicon drift detectors (SDD), achieve the best energy resolution. In this study, a 314 mm² and a 600 mm² double-sided spiral hexagonal silicon drift detector (DSSH-SDD) single cell for the pulsar soft X-ray detection is analyzed based on ultra-pure high-resistance silicon. The DSSH-SDD device is fabricated using ultra-pure high-resistivity silicon substrates patterned with ion-implanted electrodes. This study proposes a model capable of reaching a large area of 314 mm² or 600 mm² single cell and maintaining an optimal drift electric field. The design, modeling, 3D simulation, and the fabrication of the model are performed to analyze the physical performance of the DSSH-SDD. The electrical characteristics of the as-processed SDD chips, including leakage current, anode capacitance, and the spiral resistor current under the positive and negative biases are measured, and the energy resolution test is performed at the Tsinghua University. The energy resolution is an important indicator of the detector and is often expressed by full width at half maximum (FWHM). The results obtained in this study can be applied in the future for novel, flexible, large-area, high-resolution ionizing radiation detection systems capable of providing quantitative and real-time information of the relative position of spacecraft and pulsars through the pulsar X-ray radiation.

The radiation fluence of high luminosity LHC (HL-LHC) is predicted up to 1 × 10¹⁶ 1 MeV n_eq/cm² in the ATLAS and CMS experiments for the pixel detectors at the innermost layers. The increased radiation leads to the degradation of the detector properties, such as increased leakage current and full depletion voltage, and reduced signals and charge collection efficiency, which means it is necessary to develop the radiation hard semiconductor devices for very high luminosity colliders. In our previous study about ultra-fast 3D-trench electrode silicon detectors, through induced transient current simulation with different minimum ionizing particle (MIP) hitting positions, the ultra-fast response times ranging from 30 ps to 140 ps were verified. In this work, the full depletion voltage, breakdown voltage, leakage current, capacitance, weighting field and MIP induced transient current (signal) of the detector after radiation at different fluences will be simulated and calculated with professional software, namely the finite-element Technology Computer-Aided Design (TCAD) software frameworks. From analysis of the simulation results, one can predict the performance of the detector in heavy radiation environment. The fabrication of pixel detectors will be carried out in CMOS process platform of IMECAS based on ultra-pure high resistivity (up to 10⁴ ohm·cm) silicon material.

Since the advent of semiconductor detectors, they have been developed for several generations, and their performance has been continuously improved. In this paper, we propose a new silicon drift detector structure that is different from the traditional spiral SDD structure that has a gap between the cathode ring and the width of cathode ring, increasing gradually with the increase of the radius of the cathode ring. Our new structure of spiral SDD structure has equal cathode ring gap and a given surface electric field, which has many advantages compared with the traditional structure. The novel SDD structure controllably reduces the area of silicon oxide between the spiral rings, which in turn reduces the surface leakage current due to the reduction of total oxide charge in the silicon oxide and electronic states on the silicon/silicon oxide interface. Moreover, it has better controllability to adjust this spiral ring cathode gap to achieve better surface electric field distribution, thus realizing the optimal carrier drift electric field and achieving the optimal detector performance. In order to verify this theory, we have modeled this new structure and simulated its electrical properties using the Sentaurus TCAD tool. We have also analyzed and compared different spiral ring cathode gap structures (from 10 µm to 25 µm for the gap). According to the simulation results of potential, electric field, and electron concentration, we have obtained that a spiral ring cathode gap of 10 µm has the best electrical characteristics, more uniform distribution of potential and surface electric field, and a more smooth and straight electron drift channel.