Ultra-Fast 4H-SiC AC-LGAD for 4D Tracking Applications

Abstract

4H-SiC low gain avalanche detectors (LGADs) combine internal gain with the high carrier saturation drift velocity, thermal stability, and low leakage current of SiC. AC-coupled readout (AC-LGAD) adds position information to the precise timing, which enables 4D tracking. This work reports the first experimental demonstration of a 4H-SiC AC-LGAD. Devices with a 1.0×1.0~mm² active area and a 2×2 array of AC-coupled pads at a pitch of 500~μm were fabricated with two gain-layer doping concentrations, 4×10¹⁷ and 5×10¹⁷~cm⁻³, and characterized with a 375~nm ultraviolet transient current technique (UV-TCT) scanning setup. The hit position and time were reconstructed with the conventional discretized positioning circuit (DPC) and constant fraction discrimination (CFD) methods. They were also reconstructed with a transformer-based neural network, which processes the full waveforms of the four pads through a shared encoder and formulates timing as a per-sample segmentation task. With DPC and CFD, the best position and time resolutions are about 10~μm and 20~ps. The neural network mitigates the nonlinear distortions near the device edges and improves the position resolution to below 5~μm and the time resolution to about 15~ps, improvements of more than 60\% and 30\%, respectively. The higher-doped device reaches a high signal-to-noise ratio at lower bias and keeps good performance at low laser intensities. These results demonstrate the potential of 4H-SiC AC-LGADs for 4D tracking in future collider experiments.

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BibTeX RIS

BibTeX

@misc{yang2026ultrafast,
  title = {{Ultra-Fast 4H-SiC AC-LGAD for 4D Tracking Applications}},
  author = {Tao Yang and Chengxi Yang and Ben J. Sekely and Yashas Satapathy and Abraham Tishelman-Charny and Greg Allion and Gil Atar and Philip Barletta and Gabriele Giacomini and Carl Haber and Steve Holland and John F. Muth and Spyridon Pavlidis and Haichen Wang and Stefania Stucci},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.27535},
  eprint = {2610.27535},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.27535},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Ultra-Fast 4H-SiC AC-LGAD for 4D Tracking Applications
AU  - Tao Yang
AU  - Chengxi Yang
AU  - Ben J. Sekely
AU  - Yashas Satapathy
AU  - Abraham Tishelman-Charny
AU  - Greg Allion
AU  - Gil Atar
AU  - Philip Barletta
AU  - Gabriele Giacomini
AU  - Carl Haber
AU  - Steve Holland
AU  - John F. Muth
AU  - Spyridon Pavlidis
AU  - Haichen Wang
AU  - Stefania Stucci
PY  - 2026
DA  - 2026/10/20
PB  - arXiv
DO  - 10.48550/arxiv.2610.27535
UR  - https://arxiv.org/abs/2610.27535
AB  - 4H-SiC low gain avalanche detectors (LGADs) combine internal gain with the high carrier saturation drift velocity, thermal stability, and low leakage current of SiC. AC-coupled readout (AC-LGAD) adds position information to the precise timing, which enables 4D tracking. This work reports the first experimental demonstration of a 4H-SiC AC-LGAD. Devices with a 1.0×1.0~mm^2 active area and a 2×2 array of AC-coupled pads at a pitch of 500~μm were fabricated with two gain-layer doping concentrations, 4×10^17 and 5×10^17~cm^−3, and characterized with a 375~nm ultraviolet transient current technique (UV-TCT) scanning setup. The hit position and time were reconstructed with the conventional discretized positioning circuit (DPC) and constant fraction discrimination (CFD) methods. They were also reconstructed with a transformer-based neural network, which processes the full waveforms of the four pads through a shared encoder and formulates timing as a per-sample segmentation task. With DPC and CFD, the best position and time resolutions are about 10~μm and 20~ps. The neural network mitigates the nonlinear distortions near the device edges and improves the position resolution to below 5~μm and the time resolution to about 15~ps, improvements of more than 60\% and 30\%, respectively. The higher-doped device reaches a high signal-to-noise ratio at lower bias and keeps good performance at low laser intensities. These results demonstrate the potential of 4H-SiC AC-LGADs for 4D tracking in future collider experiments.
ER  -

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