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8324417 
Meetings & Symposia 
Silicon nanowire vertical arrays with porous top electrodes for trace vapor preconcentration and partial separation 
Giordano, BC; Pehrsson, PE; Johnson, KJ 
2018 
TechConnect 
3 
211-214 
English 
Silicon nanowire (SiNW) arrays are demonstrated as a suitable substrate for the preconcentration of trace nitroaromatic compounds and subsequent desorption via Joule heating of the array. Arrays are fabricated from Si wafers containing epitaxially grown layers of high conductivity p-type Si, with a relatively low conductivity intrinsic Si layer. Arrays are fabricated using a combination of nanosphere lithography (NSL) and metal-assisted chemical etching (MACE). The resulting arrays consist of ordered Si nanowires. The individual wires have a diameter of approximately 350 nm (center-to-center spacing of 500 nm) and lengths of ∼5 um. Each SiNW array chip has approximately 108 individual wires. The temperaturedependent shift of the crystalline Si Raman single phonon line was used to estimate the temperature of the array during desorption, with temperatures in excess of 200°C observed. The effectiveness of the adsorption and desorption of trace nitroaromatics, including TNT, was evaluated by coupling the array to a mass spectrometer. © 2018 OOSV. All rights reserved. 
Explosives; Joule heating; Preconcentrator; Silicon nanowire array 
Laudon, M.