Silicon nanoporous pillar array（Si-NPA）

a novel silicon micron/nanometer structural composite system with both regular surface pillar array and porous structure

is prepared by hydrothermal etching method and its ethanol-sensing properties are measured.Results show that Si-NPA exhibited high sensitivity and short response time to ethanol.This excellent performance of Si-NPA to ethanol is due to its surface structure

the high sensitivity originated from the physical adsorption brought by the large specific area

while the short response time come from the effective gas transportation pathway provided by the regular pillar array.The unique hierarchical structure of Si-NPA might be applied in the field of silicon-based thin film sensors in future.