Surface defect engineering: gigantic enhancement in the optical and gas detection ability of metal oxide sensor

Abstract

In this work, the detection ability of nanosensors can be improved extraordinarily via surface defect engineering. A kinked SnO_2−X/SnO₂ nanostructure was fabricated by tuning the oxygen flow, and this kinked SnO_2−X/SnO₂ nanostructure was used to study the mechanism of surface defect (oxygen vacancy, V_O) effects via electric measurements. For UV light sensing, the response of the SnO_2−X NW device is always better than the SnO₂ NW device, and is two orders higher under pure O₂ surrounding conditions. The detection mechanism can be clarified by changing the detection environment (oxygen concentration) and the UV light detection sensitivity can be improved by increasing the surface V_O density. Furthermore, the SnO_2−X NW device is very sensitive to its surrounding environment due to the high surface V_O density. Hence, CO/O₂ alternate-detection was used to verify our hypothesis; the results show that the SnO_2−X NW device presents great detection abilities, compared with the SnO₂ NW device. The sensitivity of the SnO_2−X NW device is two orders higher and the reset/response time is faster, compared with the SnO₂ NW device. To verify this hypothesis, the polycrystalline structure was fabricated to prove that the detection ability of metal oxide nanosensors can be improved gigantically by increasing surface defect amounts.