Radiation tolerance test and damage of single-crystal CVD Diamond sensor under high fluence particles

TL;DR

This work assesses radiation tolerance and damage mechanisms in single-crystal CVD diamond detectors under extreme irradiation. It combines neutron irradiation up to $3.3\\times10^{17}$ n cm$^{-2}$ with proton-induced degradation measurements, PL/SEM characterization, and multiscale MC+MD simulations (arc-DPA) to connect defect formation with carrier transport. A robust, defect-informed framework including a linear damage model, saturation effects, and defect overlap explains observed nonlinear degradation and enhances predictive capability beyond NIEL-based estimates. The findings establish the viability of scCVD diamond sensors for future high-radiation experiments and provide a practical pathway to tailor detector designs via defect-level modeling.

Abstract

Single-crystal chemical vapor deposition (CVD) diamond is a promising material for radiation detectors operating in extreme environments, owing to its outstanding radiation hardness. As nuclear and high-energy physics applications demand particle detectors that withstand higher radiation fluences, understanding the damage thresholds and degradation mechanisms of diamond-based detectors is essential. In this study, single-crystal CVD diamond sensors were exposed to fast neutron irradiation at fluences up to $3.3\times10^{17}$ ${n/cm^2}$. Modules exhibited stable output confirming potential for application in future high-dose radiation environments. The dominant defects were identified as point defects including <100> self interstitials, vacancies, and lattice disorder. Macroscopic defects including nanocavities and cracks were observed with areal densities approaching $10^7$ $cm^{-2}$. The impact of 100 MeV proton irradiation on diamond detector response was quantified by extracting a damage constant of $k^{100 MeV}_{proton}=(1.452\pm0.006)\times10^{-18}cm^2/(p\cdotμm)$ from a linear carrier drift degradation model. The mean free path of carriers was found to exhibit saturation behavior beyond a fluence of $4\times10^{16}$ ${p/cm^2}$ under 100 MeV proton irradiation. Monte Carlo together with molecular dynamics simulations were performed to assess irradiation induced defect and its influence on carrier transport. By considering saturation effects and defect-interaction corrections, we develop an enhanced carrier-drift degradation model that accurately captures detector response under high-dose irradiation. Furthermore, the simulation framework was applied to evaluate damage induced by protons and pions on diamond at various energies, yielding results that show better agreement with experimental data than conventional NIEL based estimates.

Figures (14)

• Figure 1: (a) Optical micrograph of a synthetic scCVD diamond plate and the metallized sensor. (b) I-V characteristics and the assembled detector module mounted on a Rogers PCB with wire-bonded connections.
• Figure 2: Fast neutron irradiation experiment. (a) Schematic of the diamond DUT exposure to neutron beam. (b) Reactor power profile of the IBR-2M facility during testing.
• Figure 3: Real-time current signal acquisition during neutron irradiation. Beam-off dose contributions have been subtracted. Data acquisition was interrupted during beam recovery, resulting in a missing interval before final stabilization.
• Figure 4: Photoluminescence spectroscopy of fast neutron radiated diamond, the upper-right inset shows the optical image after removal of the metal film.
• Figure 5: Surface morphology of crystals after fast neutron irradiation. (a) Unirradiated diamond surface. (b-d) Surface defect morphology via in-lens secondary electron imaging. (e-f) Surface topography revealed by backscattered electron imaging.