Plasma-induced oxygen vacancies enabled ultrathin ZnO films for highly sensitive detection of triethylamine

Metal oxide semiconductor (MOS) thin films hold great promise for electronic devices such as gas sensors. However, the low surface activity of pristine MOS often leads to inferior sensitivity and the sensitization mechanism of ultrathin MOS films has received rare attention. Herein, we report a high performance gas sensor based on plasma-etched ZnO thin films. The ultrathin ZnO films (20 nm) were deposited on SiO2 wafers by atomic layer deposition (ALD), which enables high-throughput production of sensor devices. The ZnO sensor shows typical n-type conductivity, which is highly variable to the exposure of triethylamine (TEA). Annealing temperature of the films is found to impact the sensor response, revealing calcination at a moderate temperature, i.e. 700 degrees C, leads to the best response. Further treatment by Ar plasma results in a remarkable decrease of sensor working temperature from 300 degrees C of untreated films to 250 degrees C and nearly 4-fold enhancement in the sensor response to 10 ppm TEA. Notably, the plasma-treated ZnO sensor also shows decent response even at room temperature (RT), which has been seldom reported for ZnO-based sensors. Structure and mechanism investigations reveal that the superior sensor properties are derived from the abundant oxygen vacancies generated by Ar plasma etching.

Automated summary

This study presents a high-performance gas sensor based on plasma-etched zinc oxide thin films, with a thickness of 20 nm deposited on SiO2 wafers by ALD. The zinc oxide sensor exhibits n-type conductivity and sensitivity to triethylamine, with the sensor response affected by annealing temperature. Ar plasma treatment results in improved sensor performance by generating oxygen vacancies.