Depth-dependent humidity sensing properties of silicon nanopillar array

Here, nanosphere lithography technique was used to fabricate silicon nanopillar arrays with various depths by controlling the etching time. These silicon nanopillar arrays were studied as a sensing material to detect humidity. Room temperature humidity sensitivity of Si-NPA sensor was investigated at a relative humidity (RH) ranging from 30 to 90% with 3 V bias voltage. And the response and recovery time were studied. As a result, the humidity sensitivity and the recovery time were increased with the increasing depth of Si nanopillar. But, the response time was reduced. Furthermore, the humidity hysteresis and the stability were measured. It is found that these two important characterizations were satisfied the requirement for humidity sensors. These sensing characteristics indicate that Si-NPA might be a practical sensing material.