He+ LEIS analysis combined with pulsed jet technique of ethanol sensing by a ZnO surface

Crystal plane‐dependent ethanol gas sensing of ZnO studied by low‐energy He+ ion scattering combined with pulsed jet technique

“…Figure 2A shows the sensing response curve of the c (+) plane to EtOH of 50 ppmv measured under the static atmospheric pressure at 673 K. The features of the response curve, that is, the increase (decrease) of the resistance caused by exposing to the air (the trace EtOH), is a typical characteristic for a ZnO surface interacting with a reducing gas, such as EtOH. In our previous study, it was demonstrated that this sensing response to EtOH under atmospheric pressure is well reproduced by the pulsed jet irradiation by optimizing the pulse width and the pulse interval while keeping the background pressure low enough to operate He + ‐LEIS 23 . Figure 2B shows the Zn peak intensity of LEIS during the pulsed jet irradiation at 673 K with those conditions (pulse width: 10 ms, pulse interval: 5 s).…”

“…The incident energy was 1.77 keV. The combined apparatus of He + LEIS and the pulsed jet technique has been described elsewhere 23 . Briefly, the inlet gas was either the G1‐grade synthesized air or the EtOH (50 ppmv)‐air mixed gas.…”

“…In the present study, the ZnO crystal plane dependence of the EtOH sensing was investigated from an analytical approach using a single‐crystalline bulk substrate for four dominant low‐index surfaces: Zn‐terminated (0001) ( c (+)), O‐terminated (000 ) ( c (−)), (10 0) ( m ), and (11 0) ( a ). For this purpose, we applied a newly developed low‐energy He + ion scattering spectroscopy (He + ‐LEIS) combined with the pulsed jet technique 23 . In this method, the free gas jet is periodically blown onto the sample surface to realize transient near‐atmospheric pressure in the vicinity of the surface.…”