Room Temperature Sensing of O2 and CO by Atomic Layer Deposition Prepared ZnO Films Coated with Pt Nanoparticles

Abstract

Ultralow-power gas sensing devices need to operate without an energy consuming heater element. This requires the design of sensing devices that are so efficient that they can operate at room temperature (RT). Here, we report on the RT sensing performance of atomic layer deposition (ALD) prepared i-ZnO and Al-doped ZnO sensing devices. The sensitivity of these devices has been catalytically enhanced with ALD Pt nanoparticles (NPs). It was shown that the size distribution of the Pt NPs can be controlled by the number of Pt-ALD cycles. The Pt-enhanced sensing devices showed a reversible, proportional change in current response at RT upon exposure to O2 and CO. O2 could be detected, diluted in N2, down to 0.5%. CO could be detected, diluted in N2 in the presence of O2 and H2O, down to 20 ppm. Reference devices without Pt NPs showed no response, indicating the importance of the Pt NPs for the sensing mechanism.