arXiv subjects

Chuan Liao

Publications and source records attributed to Chuan Liao.

6 recordsLinked to original sources

arXiv2026

Development of Small-pitch, Ultra-thin 3D Silicon Sensors at USTC

We report on the development of 3D silicon sensors at the University of Science and Technology of China (USTC). The sensor involves columnar electrodes (5 um in diameter) of both doping types, etched from the same wafer side. The p+ electrodes pass through the epitaxial wafer, whereas the n+ electrodes stop at a short distance from the opposite side of the epitaxial wafer. With respect to previous generations of 3D sensors, they feature an ultra-thin active substrate (50 um) and a small pixel size of 50 um x 50 um or 25 um x 25 um. This R&D project aims to establish a sensor technology to simultaneously measure position and time information at the single-pixel level. The first run with one merged wafer layout has been completed. The design, fabrication, and characterization of the sensors are reported in this paper.

physics.ins-det↗

arXiv2026

Design and Characterization of Racetrack 3D-Trench Silicon Sensor Based on 8-Inch Process with Excellent Time Resolution

In the extreme environments of high-luminosity colliders, traditional planar silicon sensors suffer severe radiation-induced performance degradation and fail to satisfy the stringent demands of high-precision tracking and high-speed timing in particle physics. 3D silicon sensors enhance radiation hardness by shortening charge collection distance, yet conventional designs with columnar or square-cell trench electrodes exhibit non-uniform electric fields, including saddle points and low-field regions, which degrade charge collection efficiency and timing resolution. This work presents a novel racetrack 3D-trench silicon sensor with continuous racetrack electrodes surrounding a long central collection electrode, aiming to eliminate electric field inhomogeneities. For the first time, a 23 $\mu $m shallow-etched device was fabricated on an 8-inch platform, which provides a promising basis for its subsequent mass production and engineering applications. The device performance was systematically evaluated through theoretical analysis, 3D TCAD simulations, and characterization using semiconductor parameter analyzers and transient current technique (TCT) measurements. The sensor achieves leakage current below 0.2 nA, breakdown voltage above 110 V, full depletion voltage as low as a few volts, capacitance as low as 650 fF, collected charge of 4 fC, time response of about 640 ps, and time resolution of 50 ps. This large-scale manufacturable, shallow-etched racetrack 3D-trench silicon sensor provides a competitive device solution for portable radiation detection and next-generation 4D tracking under high-radiation and high-event-rate conditions.

physics.ins-det↗

arXiv2025

Defects and acceptor removal in 60Co {\gamma}-irradiated p-type silicon

Boron-doped silicon detectors used in high radiation environments like the future HL-LHC show a degradation in device performance due to the radiation induced deactivation of the active boron dopant. This effect, known as the so-called Acceptor Removal Effect (ARE), depends on particle type, particle energy and radiation dose and is usually explained by the formation of boroninterstitial - oxygen-interstitial (BiOi) defects that induce a donor-type defect level in the upper part of the Si band gap. Here we present defect characterization studies using Thermally Stimulated Current technique (TSC) and Deep Level Transient Spectroscopy (DLTS) on a set of epitaxially grown p-type silicon diodes of different resistivity, irradiated with 60Co {\gamma}-rays. We used the defect parameters (activation energy, charge carrier capture cross sections and defect concentration) obtained from DLTS experiments for modeling the corresponding TSC spectra, and subsequently compared those with the experimental TSC results. This approach shows that the di-vacancy which is well characterized by DLTS correlates with the so-far unspecified charge emission signal of the X-defect that partially overlaps with the BiOi peak in TSC spectra. Additionally, in order to evaluate the impact of BiOi defect formation on the macroscopic properties of the device, we compared the BiOi defect concentration with the change in the effective carrier concentration Neff obtained from C-V measurements. It shows that the variations in Neff are about twice the changes in the BiOi concentration, which is in perfect consistency with the assumption of boron deactivation by the formation of the BiOi donor in irradiated p-type Si.

hep-ex↗

arXiv2023

Investigation of high resistivity p-type FZ silicon diodes after 60Co γ-irradiation

In this work, the effects of $^\text{60}$Co $γ$-ray irradiation on high resistivity $p$-type diodes have been investigated. The diodes were exposed to dose values of 0.1, 0.2, 1, and \SI{2}{\mega Gy}. Both macroscopic ($I$--$V$, $C$--$V$) and microscopic (Thermally Stimulated Current~(TSC)) measurements were conducted to characterize the radiation-induced changes. The investigated diodes were manufactured on high resistivity $p$-type Float Zone (FZ) silicon and were further classified into two types based on the isolation technique between the pad and guard ring: $p$-stop and $p$-spray. After irradiation, the macroscopic results of current-voltage and capacitance-voltage measurements were obtained and compared with existing literature data. Additionally, the microscopic measurements focused on the development of the concentration of different radiation-induced defects, including the boron interstitial and oxygen interstitial (B$_\text{i}$O$_\text{i}$) complex, the carbon interstitial and oxygen interstitial C$_\text{i}$O$_\text{i}$ defect, the H40K, and the so-called I$_\text{P}^*$. To investigate the thermal stability of induced defects in the bulk, isochronal annealing studies were performed in the temperature range of \SI{80}{\celsius} to \SI{300}{\celsius}. These annealing processes were carried out on diodes irradiated with doses of 1 and \SI{2}{\mega Gy} and the corresponding TSC spectra were analysed. Furthermore, in order to investigate the unexpected results observed in the $C$-$V$ measurements after irradiation with high dose values, the surface conductance between the pad and guard ring was measured as a function of both dose and annealing temperature.

physics.ins-det↗

arXiv2023

Investigation of the Boron removal effect induced by 5.5 MeV electrons on highly doped EPI- and Cz-silicon

This study focuses on the properties of the B$_\text{i}$O$_\text{i}$ (interstitial Boron~-~interstitial Oxygen) and C$_\text{i}$O$_\text{i}$ (interstitial Carbon~-~interstitial Oxygen) defect complexes by \SI{5.5}{\mega\electronvolt} electrons in low resistivity silicon. Two different types of diodes manufactured on p-type epitaxial and Czochralski silicon with a resistivity of about 10~$Ω\cdot$cm were irradiated with fluence values between \SI{1e15}{\per\square\centi\meter} and \SI{6e15}{\per\square\centi\meter}. Such diodes cannot be fully depleted and thus the accurate evaluation of defect concentrations and properties (activation energy, capture cross-section, concentration) from Thermally Stimulated Currents (TSC) experiments alone is not possible. In this study we demonstrate that by performing Thermally Stimulated Capacitance (TS-Cap) experiments in similar conditions to TSC measurements and developing theoretical models for simulating both types of B$_\text{i}$O$_\text{i}$ signals generated in TSC and TS-Cap measurements, accurate evaluations can be performed. The changes of the position-dependent electric field, the effective space charge density $N_\text{eff}$ profile as well as the occupation of the B$_\text{i}$O$_\text{i}$ defect during the electric field dependent electron emission, are simulated as a function of temperature. The macroscopic properties (leakage current and $N_\text{eff}$) extracted from current-voltage and capacitance-voltage measurements at \SI{20}{\celsius} are also presented and discussed

physics.app-ph↗

arXiv2022

Defect characterization studies on neutron irradiated boron-doped silicon pad diodes and Low Gain Avalanche Detectors

High-energy physics detectors, like Low Gain Avalanche Detectors (LGADs) that will be used as fast timing detectors in the High Luminosity LHC experiments, have to exhibit a significant radiation tolerance. Thereby the impact of radiation on the highly boron-doped gain layer that enables the internal charge multiplication, is of special interest, since due to the so-called Acceptor Removal Effect (ARE) a radiation-induced deactivation of active boron dopants takes place. In this paper we present defect-spectroscopy measurements (Deep-Level Transient Spectroscopy and Thermally Stimulated Current technique) on neutron irradiated p-type silicon pad diodes of different resistivity as well as LGADs irradiated at fluences up to 1 x 10^15 neq/cm2. Thereby we show that while for the silicon pad diodes irradiated with electrons, neutrons or protons the determination of defect electronic properties and defect introduction rates is straightforward, DLTS and TSC measurements on LGADs are strongly influenced by the impact of the gain layer. It is shown that the measurability of the capacitance of the gain layer shows a strong frequency and temperature dependence leading to a capacitance drop in DLTS and non-reliable measurement results. With TSC defects formed in the LGADs can be very nicely observed and compared to the defects formed in the silicon pad diodes. However the exact assignment of defects to the gain layer or bulk region remains challenging and the charge amplification effect of the LGADs impacts the exact determination of defect concentrations. Additionally, we will demonstrate that depending on the TSC measurement conditions defect induced residual internal electric fields are built up in the irradiated LGADs that are influencing the current signal of carriers emitted from the defect states.

physics.ins-det↗