Enhanced Secondary-Electron Detection of Single-Ion Implants in Silicon through Thin SiO₂ Layers

Deterministic placement of single dopants is essential for scalable quantum devices based on Group V donors in silicon. We demonstrate a nondestructive, high-efficiency method for detecting individual ion implantation events using secondary electrons (SEs) in a focused-ion-beam system. Using low-energy Sb ions implanted into undoped silicon, we achieve up to 98 ± 1% single-ion detection efficiency (DE). We find that introducing thin, controlled SiO₂ capping layers enhances the SE yield, consistent with the increased electron mean-free path in the oxide, while maintaining successful ion deposition in the underlying silicon substrate. Our approach provides a robust and scalable route to precise donor placement and extends deterministic implantation strategies to a broad range of material systems and quantum device architectures.