Extremely thin silicon ΔE detectors for ion beam analysis

Abstract

Recent developments in silicon nanotechnology have made feasible the fabrication of ΔE detectors with thickness of 1 μm or less. The CHICSi collaboration has been developing thin ΔE detectors for study of reaction products from intermediate energy heavy ion collisions in an ultra high vacuum storage-ring environment. In this paper, we highlight these developments from an ion beam analysis (IBA) viewpoint. The initial part of the paper outlines the characteristics for these detectors for, nuclear reaction analysis (NRA), elastic recoil detection (ERD) using ΔE− E detector telescopes and accelerator mass spectrometry (AMS). Quasi-empirical estimates of the maximum ΔE detector thickness and separating power for the limit of low energy particles (down to 0.1A MeV) reveal that energy straggling is an important limiting factor. Subsequently different methods are presented for fabricating both self-supported and vertically integrated ΔE detectors including recently developed wafer bonding techniques which open up the possibility of producing ΔE− E detector telescopes where the ΔE element is in the hundreds of nm range. Ultimately consideration is given to special requirements for the readout electronics because of the high capacitance presented by the thin ΔE detectors.