arXiv subjects

Adam Klimsza

Publications and source records attributed to Adam Klimsza.

4 recordsLinked to original sources

arXiv2026

Effects of irradiation by protons, neutrons, and gamma particles on electrical properties of 4H-SiC diodes and LGAD sensors

4H-SiC is a wide-bandgap semiconductor with high displacement threshold energy, large critical electric field, and low intrinsic carrier concentration, making it attractive for radiation-hard detector applications. In this work, we investigate the electrical characteristics of 4H-SiC P$^{+}$-in-N (PN) diodes and Low-Gain Avalanche Detectors (LGADs) fabricated by onsemi before and after irradiation by 24 GeV/c protons, reactor neutrons, and $^{60}$Co gamma rays. Current-voltage (IV) and capacitance-voltage (CV) measurements were performed at room temperature for proton fluences up to $1\times10^{16}\;\mathrm{protons/cm^2}$, neutron fluences up to $1\times10^{18}\;\mathrm{1\;MeV\;n_{eq}/cm^2}$, and total ionizing doses up to 300 kGy. Hadron irradiation induces pronounced changes in both leakage current and bulk capacitance, consistent with radiation-induced formation of deep acceptor-like defects and strong compensation of the originally N-type material. For high proton fluences, the leakage current decreases and the bulk capacitance becomes bias-independent, indicating effective compensation of the epitaxial layer. Extreme neutron fluences lead to a substantial expansion of the depleted region into the originally highly doped substrate, as inferred from the measured capacitance values. Gamma irradiation up to 300 kGy results in significantly modified capacitance behavior, suggesting reduction of the effective doping concentration in the epitaxial and multiplication layers. The results demonstrate that radiation-induced compensation strongly modifies the effective space charge in 4H-SiC devices at high hadron fluences, while the leakage current is influenced by the enlarged depletion volume together with field-enhanced and surface-related generation mechanisms. In contrast, ionizing damage primarily affects the effective doping and electric-field distribution.

physics.ins-det↗

arXiv2026

Development of Segmented 4H-SiC LGADs

The wide-bandgap semiconductor 4H-silicon carbide (4H-SiC) offers a compelling combination of radiation hardness, thermal stability, and high critical electric field for particle detection in harsh environments. To compensate for the comparatively low charge generation in SiC, the Low-Gain Avalanche Detector (LGAD) concept can be adopted to provide internal signal amplification. Building on three preceding generations of single-pad 4H-SiC LGAD prototypes fabricated by ion implantation, this work presents the design, fabrication, and initial characterization of segmented 4H-SiC LGAD devices -- the first fabricated and characterized devices reported. Strip detectors with 80~$\mu$m pitch and pixel arrays with 55 and 110~$\mu$m pitch were produced using multiple inter-channel isolation strategies, including geometric separation and oxide-filled trenches. Two-photon absorption transient current technique (TPA-TCT) measurements performed at ELI ERIC demonstrate clear charge separation between adjacent strips with internal gain, confirming functional segmentation.

physics.ins-det↗

arXiv2025

Exploring the Design and Measurements of Next-Generation 4H-SiC LGADs

This contribution presents the design, production, and initial testing of newly developed 4H-SiC Low Gain Avalanche Detectors (LGADs). The evaluation includes performance metrics such as the internal gain layer's efficiency in enhancing signal generation. Initial laboratory and Transient Current Technique (TCT) measurements provide insight into the device's stability and response to the signal. Due to the increase of availability provided by the industry, 4H-SiC is emerging as a strong candidate for the next-generation of semiconductor detectors. Such sensors are promising due to the inherent radiation tolerance of 4H-SiC and its stable operation across a wide temperature range. However, due to the wider-bandgap of 4H-SiC compared to standard silicon, and difficulty to produce high-quality layers thicker than 50 \textmu m, an internal charge multiplication layer needs to be introduced. The presented 4H-SiC LGADs, fabricated by onsemi, are optimized for an N-type substrate and epi wafer. The initial TCT and laboratory test results demonstrate fast charge collection and uniform multiplication across multiple samples produced on a single wafer.

physics.ins-det↗

arXiv2025

First generation 4H-SiC LGAD production and its performance evaluation

This contribution will delve into the design and performance of the newly produced Silicon Carbide Low Gain Avalanche Detectors (4H-SiC LGADs) and provide a comprehensive summary of their measured characteristics. This includes an analysis of the detector's performance, temperature stability, and the effectiveness of the internal gain layer in improving signal generation. The 4H-SiC is re-emerging as a strong candidate for the next generation of semiconductor detectors. This material offers several advantages, including high radiation tolerance and the ability to operate over a wide range of temperatures without significant annealing effects. However, the signals generated by minimum ionizing particles in the 4H-SiC detector are lower compared to the signal produced by standard silicon detectors due to their higher bandgap energy. This is addressed by implementing a charge multiplication layer, which results in the intrinsic gain of the device. The presented 4H-SiC LGADs produced by onsemi are specifically designed and optimized for fabrication on the n-type substrate/epi wafer with the gain layer implanted approximately $1~\mathrm{\mu m}$ below the surface. The first iteration of these LGAD structures was manufactured in early 2024 and since then has been subjected to laboratory evaluation. The measured properties of these detectors align well with the predictions arising from the extensive TCAD simulation studies.

physics.ins-det↗