Ultra-thin corrugated metamaterial film as large-area transmission dynode. (1st September 2022)

• Record Type: Journal Article
• Authors: Chan, H.W.; Prodanović, V.; Theulings, A.M.M.G.; ten Bruggencate, T.; Hagen, C.W.; Sarro, P.M.; v.d. Graaf, H.
• Is Part Of: Journal of instrumentation. Volume 17:Number 9(2022)
• Publication Date: 2022-09-01
• Subjects: Secondary electron emitters and dynodes and their production -- Avalanche-induced secondary effects -- Electron multipliers (vacuum); Scientific apparatus and instruments -- Periodicals; 502.84
• DOI: 10.1088/1748-0221/17/09/P09027
• Languages: English
• ISSNs: 1748-0221

Abstract

Abstract: Large-area transmission dynodes were fabricated by depositing an ultra-thin continuous film on a silicon wafer with a 3-dimensional pattern. After removing the silicon, a corrugated membrane with enhanced mechanical properties was formed. Mechanical metamaterials, such as this corrugated membrane, are engineered to improve its strength and robustness, which allows it to span a larger surface in comparison to flat membranes while the film thickness remains constant. The ultra-thin film consists of three layers (Al2 O3 /TiN/Al2 O3 ) and is deposited by atomic layer deposition (ALD). The encapsulated TiN layer provides in-plane conductivity, which is needed to sustain secondary electron emission. Two types of corrugated membranes were fabricated: a hexagonal honeycomb and an octagonal pattern. The latter was designed to match the square pitch of a CMOS pixel chip. The transmission secondary electron yield was determined with a collector-based method using a scanning electron microscope. The highest transmission electron yield was measured on a membrane with an octagonal pattern. A yield of 2.15 was achieved for 3.15 keV incident electrons for an Al2 O3 /TiN/Al2 O3 tri-layer film with layer thicknesses of 10/5/15 nm. The variation in yield across the surface of the corrugated membrane was determined by constructing a yield map. The active surface for transmission secondary electron emission is near 100%, i.e. a primary electron generates transmission secondary electrons regardless of the point of impact on the corrugated membrane.