Oxygen vacancy-dependent humidity sensing performance induced by Si doping on SnO2 nanoparticles

Abstract

In this work, we investigated the effects of Si doping on the oxygen vacancy defects in SnO₂ nanoparticles for detecting changes in humidity levels. XRD measurements showed that all samples exhibit tetragonal rutile phase and the crystallite structure of SnO₂ was tuned with Si content increasing. XPS analysis revealed more oxygen vacancies defects (the percentage of O_V increases from 11.52 % to 19.02 %) were confirmed to be produced, accelerating chemisorption of water molecules on Si doped SnO₂ surface. Additionally, we discussed the various situations involving the utilization of electrons and holes corresponding to the different states of oxygen vacancies via photoluminescence spectroscopy. The humidity sensing results exhibited that the 5 mol% Si doped SnO₂ humidity sensor shows high sensitivity, low hysteresis (5.7 %) and fast response/recovery times (7 s/10 s) range from 11 % to 95 % relative humidity. The chemical mechanisms for enhancement in humidity performance induced by oxygen vacancy defects formed on SnO₂ surface is proposed.