CuO-doped BSST thick film resistors for ppb level H2S gas sensing at room temperature

An effort has been made to develop a heterojunction type CuO-(Ba0.8Sr0.2)(Sn0.8Ti0.2)O3 (BSST) gas sensor which could detect an extremely small amount of H2S gas at room temperature. The BSST solid solution was prepared mechanochemically. Copper was doped in the BSST ceramics by adding CuCl2, followed by sintering at 550 °C for 2 h. Sintering converts CuCl2 into CuO. CuO is known to be p-type and BSST as an n-type semiconductor. Copper oxide grains in association with BSST form p-CuO/n-BSST heterojunctions. The thick films of CuO-BSST were prepared by screen-printing technique. The CuO-BSST heterojunction gas sensor is a new type gas sensor and has many advantages, such as low cost, simple processing, and convenient testing. This sensor was observed to be highly sensitive and selective to a ppb level of H2S gas at room temperature.