Thin silicon solid-state detectors for energetic particle measurements

Abstract

Context. Silicon solid-state detectors are commonly used for measuring the specific ionization, dE∕dx, in instruments designed for identifying energetic nuclei using the dE∕dx versus total energy technique in space and in the laboratory. The energy threshold and species resolution of the technique strongly depend on the thickness and thickness uniformity of these detectors. Aims. Research has been carried out to develop processes for fabricating detectors that are thinner than 15 μm, that have a thickness uniformity better than 0.2 μm over cm2 areas, and that are rugged enough to survive the acoustic and vibration environments of a spacecraft launch. Methods. Silicon-on-insulator wafers that have a device layer of the desired detector thickness supported by a thick handle layer were used as starting material. Standard processing techniques were used to fabricate detectors on the device layer, and the underlying handle-layer material was etched away leaving a thin, uniform detector surrounded by a thick, supporting frame. Results. Detectors as thin as 12 μm were fabricated in two laboratories and successfully subjected to environmental and performance tests. Two detector designs were used in the High-energy Energetic Particles Instrument, which is part of the Integrated Science Investigation of the Sun instrument suite on NASA’s Parker Solar Probe spacecraft. These detectors have been performing well for more than two years in space. Conclusions. Thin silicon detectors in d E∕dx versus total energy instruments enable the identification of nuclei with energies down to ~1 MeV nuc−1. This research suggests that detectors at least a factor of two thinner should be achievable using this fabrication technique.

From SuperTIGER to TIGERISS

“…All TIGERISS systems must meet TRL standards for launch and the ISS environment that exceed those of balloon payloads, and systems that are changed from SuperTIGER particularly benefit from heritage with other instruments. Silicon detectors have been used on many space missions, including ACE-CRIS [42], Light Imager for Gamma-ray Astrophysics (AGILE) [43], Alpha Magnetic Spectrometer (AMS-02) [44], Energetic Particles: Acceleration, Composition, and Transport investigation (EPACT) on the Global Geospace Science (GGS) Wind satellite [45], Fermi-Large Area Telescope (Fermi-LAT) [46], Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) [47], Parker Solar Probe [48], and the Solar Terrestrial Relations Observatory (STEREO) [49]. TIGERISS will use daisy-chained detector ladders that are particularly similar to those used in AMS-02 [44] and Fermi-LAT [46].…”

Measurement of ionization loss of 50 GeV protons in silicon with smoothly tunable up to 1 cm thickness using a single flat detector

“…In all these cases, high-energy charged particles can cross silicon crystals at different angles due to interactions with targets or external fields. Both single flat diodes (for 𝑑𝐸/𝑑𝑥 measurements) [19] and strip or pixel detectors (for particle tracking) [1,20]- [22] can be used. However, detectors with sub-millimeter thickness of the depleted layer installed perpendicularly to a particle beam are usually utilized in such applications and in related research of ionization loss.…”