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

Cuprous Oxide (Cu ₂ O) is an important p-type semiconductor. Several micro and nano-structures of Cu ₂ O have been employed in sensing oxidizing and reducing gases. However, for mass production of sensors, large-area Cu ₂ O films are needed, which hitherto was a challenge. In this work we report a chemiresistive gas sensor based on pure-phase Cu ₂ O (~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 ( τ response ) and recovery time ( τ recovery ) of the device were found to be decent for practical applications. Unlike competing techniques for Cu ₂ O deposition, Cu ₂ O from chemical-vapor deposition leads to sensors that are more repeatable, stable and reproducible.