Top-Down Approaches for 10 nm-Scale Nanochannel: Toward Exceptional H 2 S Detection.

Metal oxide semiconductors (MOS) have proven to be most powerful sensing materials to detect hydrogen sulfide (H 2 S), achieving part per billion (ppb) level sensitivity and selectivity. However, there has not been a way of extending this approach to the top-down H 2 S sensor fabrication process, completely limiting their commercial-level productions. In this study, we developed a top-down lithographic process of a 10 nm-scale SnO 2 nanochannel for H 2 S sensor production. Due to high-resolution (15 nm thickness) and high aspect ratio (>20) structures, the nanochannel exhibited highly sensitive H 2 S detection performances ( R a / R g = 116.62, τ res = 31 s at 0.5 ppm) with selectivity ( R H 2 S / R acetone = 23 against 5 ppm acetone). In addition, we demonstrated that the nanochannel could be efficiently sensitized with the p-n heterojunction without any postmodification or an additional process during one-step lithography. As an example, we demonstrated that the H 2 S sensor performance can be drastically enhanced with the NiO nanoheterojunction ( R a / R g = 166.2, τ res = 21 s at 0.5 ppm), showing the highest range of sensitivity demonstrated to date for state-of-the-art H 2 S sensors. These results in total constitute a high-throughput fabrication platform to commercialize the H 2 S sensor that can accelerate the development time and interface in real-life situations.