Pt–Ti–O gate silicon–metal–insulator–semiconductor field-effect transistor hydrogen gas sensors in harsh environments

Abstract

Abstract The influence of radiation damages to developed hydrogen gas sensor chips from γ-rays ( 60 Co) and/or X-rays (synchrotron radiation) is manageably avoided for sensor operations even at extremely high integral doses such as 1.8 and/or 18 MGy. Platinum–titanium–oxygen (Pt–Ti–O) gate silicon–metal–insulator–semiconductor field-effect transistor (Si-MISFET) hydrogen gas sensors can work stably as hydrogen sensors up to about 270 °C and also show environmental hardness as follows: When nitrogen-diluted 10-ppm hexamethyldisiloxane (HMDS) was exposed to the sensor FETs for 40 min at a working temperature of 115 °C, large sensing amplitude (Δ V g ) changed little within repetition errors before and after HMDS exposures. The variations of Δ V g among relative humidity of 20 and 80% are very small within ±4.4% around 50% under 40 °C atmosphere. The Pt–Ti–O sensors have been found to show large Δ V g of 624.4 mV with σΔ V g of 7.27 mV for nine times repeated measurements under nitrogen-diluted 1.0%-hydrogen gas, which are nearly the same values of 654.5 mV with σΔ V g of 3.77 mV under air-diluted 1.0%-hydrogen gas.