Humidity Sensing of SnO/Porous Silicon Heterojunctions

Abstract

A nanoparticle metal oxide SnO thin film fabricated on Porous Silicon (PS) is studied as a subject for room temperature humidity sensing device application. The structural, photoluminescence, optical and electrical properties of thin films and SnO/PS/Si heterostructures are studied. Current-voltage characteristics of SnO/PS/Si heterojunctions are measured under normal atmosphere and humid environment in the range of 62-95% RH. The humidity-resistance effect, i.e., decrease of resistance between contacts to SnO and Si substrate under humidity exposition is obtained for SnO/PS/Si heterostructures at room temperature. The structure shows well pronounced response-recovery behavior (response time about 1min) after successive cycles of placing in humid environment. The similar dependence is observed for the capacitance under humidity. The mechanism for the humidity-stimulated electricity in SnO/PS/Si sensor at room temperature is discussed.