Regulation of electronic properties of ZnO/InO heterospheres atomic layer deposition for high performance NO detection

Metal oxide semiconductor heterostructures are promising for gas sensors due to their unique chemical and electronic properties at the heterointerface. In this work, a highly sensitive and selective gas sensor for the detection of nitrogen dioxide (NO 2 ) is reported based on In 2 O 3 /ZnO heterogeneous nanospheres designed by atomic layer deposition (ALD). Their electronic properties at the In 2 O 3 /ZnO heterogeneous interface can be tuned by varying ZnO ALD cycles. Gas sensing tests show that ZnO ALD significantly improves the sensor performance of In 2 O 3 nanospheres, rendering a response of 7.9 to 10 ppm NO 2 even at room temperature (RT). The sensor based on In 2 O 3 /ZnO with 30 cycles of ZnO ALD delivers the best response of 139.9 to 10 ppm NO 2 at an operating temperature of 180 °C, showing a nearly 6-fold enhancement over pristine In 2 O 3 . Meanwhile, the In 2 O 3 /ZnO sensor also exhibits a low limit of detection of 35 ppb, which allows for reliable detection of sub-ppm NO 2 . The excellent sensor performances are correlated to the modulation of electron depletion layers at the In 2 O 3 /ZnO heterointerface, which sheds some light on designing new materials via ALD for the detection of hazardous gas molecules. Heterogeneous In 2 O 3 /ZnO spheres designed by atomic layer deposition manifest high response to NO 2 detection.