CVD Grown Cuprous Oxide Thin Film Based High Performance Chemiresistive Ammonia Gas Sensors

Cuprous Oxide (Cu2O) is an important p-type semiconductor. Several micro and nano-structures of Cu2O have been employed in sensing oxidizing and reducing gases. However, for mass production of sensors, large-area Cu2O films are needed, which hitherto was a challenge. In this work we report a chemiresistive gas sensor based on pure-phase Cu2O (~90 nm thick), synthesized by chemical vapor deposition (CVD). At an operating temperature of 200°C, the sensor is highly-sensitive to ammonia. The device response varies from 0.81% to 5.21%, when exposed to ammonia with concentration of 300 ppb to 3 ppm. The response time ( $\tau _{{\it\text { response}}}$ ) and recovery time ( $\tau _{{\it\text { recovery}}}$ ) of the device were found to be decent for practical applications. Unlike competing techniques for Cu2O deposition, Cu2O from chemical-vapor deposition leads to sensors that are more repeatable, stable and reproducible.