Depth-dependent humidity sensing properties of silicon nanopillar array

Fabrication of Ordered SnO2 Nanostructures with Enhanced Humidity Sensing Performance

“…At first, a monolayer of polystyrene (PS) nanosphere with 220 nm in diameter was fabricated on Si substrate by self-assembly ( Figure 1 a). The self-assembly method was described in detail in our previous work [ 25 ]. Next, the prepared substrate with PS spheres was etched by reaction ion etching (RIE) with oxygen under these conditions: chamber pressure 1 Torr, RF power 20 W, O 2 flow 20 sccm, and etching time 30 s. O 2 plasma was applied to shrink the PS nanospheres ( Figure 1 b).…”

“…These nanostructures have a classic honeycomb structure, which can provide a much larger surface area, compared to bulk materials. In our previous work, it was reported that an ordered silicon nanopillar array prepared by nanoshpere lithography exhibited excellent humidity-sensing properties [ 24 , 25 , 26 ]. Here, the ordered SnO 2 nanostructure was studied as a new nanostructure material for gas sensors.…”

Organic Vapour Sensing Properties of Area-Ordered and Size-Controlled Silicon Nanopillar

“…The period and density of the nanopillar arrays are determined by the initial diameter of the polystyrene spheres. The silicon nanopillar array is 220 nm in period, and the density is ~10 9 /cm 2 .Obviously, the valleys around the pillar are intercommunicated and form an effective pathway for vapour transportation into or out of Si-NPA [22,23]. …”

“…Tan et al reported that a highly sensitive ethanol gas sensor was designed based on the mechanism of ethanol quasi-molecular imprinting [19]. Although these gas sensors demonstrated excellent performance, further development of Si-based material sensors—such as porous silicon [20,21] and silicon pillar [22,23]—is desirable, as it would make the assembly of the sensors much simpler, cheaper, and more portable because of their ease in integrating with the already-existing Si integrated circuit technology.…”

“…Excellent humidity sensing properties, including high sensitivity and fast response rate, were achieved [22,23]. In this paper, the room-temperature organic vapour (ethanol and acetone gas) sensing properties of Si-NPA were studied, and the underlying mechanisms were analysed based on its unique surface structure, morphology, and physical properties.…”