Influence of Electrical Modes on Radiation Sensitivity of Hydrogen Sensors Based on Pd-Ta2O5-SiO2-Si Structures

The influence of the circuit’s electric modes on the radiation sensitivity of hydrogen sensors based on the metal-insulator-semiconductor field-effect transistor with structure Pd-Ta2O5-SiO2-Si (MISFET) was investigated. There were measured the hydrogen responses of output voltages V of the MISFET-based circuits at different gate voltages before and after the electron irradiations. The voltages V as functions of hydrogen concentration C were determined for different ionizing doses D. Models of influence of the electric modes on the radiation sensitivity of sensors were based on experimental dependencies of V(C, D). The recommendations for the optimal choice of MISFET-based circuit’s electric modes were formulated

Performance Degradations of MISFET-Based Hydrogen Sensors with Pd-Ta₂O₅-SiO₂-Si Structure at Long-Time Operation

There are presented the generalized results of studies of performance degradation of hydrogen sensors based on MISFET with structure Pd-Ta2O5-SiO2-Si. It was shown how responses’ parameters change during long-term tests of sensors under repeated hydrogen impacts. There were found two stages of time-dependence response’ instability, the degradation degree of which depends on operating conditions, hydrogen concentrations and time. To interpret results there were proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based devices for long-time operation

Performance Degradations of MISFET-Based Hydrogen Sensors with a Pd-Ta₂O₅-SiO₂-Si Structure During Long-Term Operation

We present the generalized experimental results of performance degradation of hydrogen sensors based on metal-insulator-semiconductor field effect transistor (MISFET)with the structure Pd-Ta2O5-SiO2-Si. The n-channel MISFET elements were fabricated on silicon single chips together with temperature sensors and heater-resistors by means of conventional -technology. Two hundred cycles of responses to different hydrogen concentrations were measured during eight weeks using special measuring and temperature stabilization circuitries with a feedback loop based on the chip’s thermo-sensor and heater. We show how the response parameters change during long-term tests of sensors under repeated hydrogen impacts. There were two stages of time-dependent response instability, the degradation of which depends on operating conditions, hydrogen concentrations, and time. To interpret results, we proposed the models, parameters of which were calculated using experimental data. These models can be used to predict performances of MISFET-based gas analysis devices for long-term operation

Effect of Temperature and Electrical Modes on Radiation Sensitivity of MISFET Dose Sensors

The temperature and electrical modes influences on radiation sensitivity of n-channel MISFETs sensors of the total ionizing dose were investigated. There were measured the MISFET-based dosimeter output voltages V as function of the radiation doses D at const values of the drain current ID and the drain–source voltage VD, as well as the (ID–VG) characteristics before, during and after irradiations at different temperatures T (VG is the gate voltage). It was shown how the conversion function V(D) and the radiation sensitivity SD are depending on the temperature T for different electrical modes. To interpret experimental data there were proposed the models taking into account the separate contributions of charges in the dielectric Qt and in SiO2–Si interface Qs. The model’s parameters ΔVt(D,T) and ΔVs(D,T) were calculated using the experimental ID–VG characteristics. These models can be used to predict performances of MISFET-based devices

MOSFE-Capacitor Silicon Carbide-Based Hydrogen Gas Sensors

The features of the wide band gap SiC semiconductor use in the capacitive MOSFE sensors’ structure in terms of the hydrogen gas sensitivity effect, the response speed, and the measuring signals’ optimal parameters are studied. Sensors in a high-temperature ceramic housing with the Me/Ta2O5/SiCn+/4H-SiC structures and two types of gas-sensitive electrodes were made: Palladium and Platinum. The effectiveness of using Platinum as an alternative to Palladium in the MOSFE-Capacitor (MOSFEC) gas sensors’ high-temperature design is evaluated. It is shown that, compared with Silicon, the use of Silicon Carbide increases the response rate, while maintaining the sensors’ high hydrogen sensitivity. The operating temperature and test signal frequency influence for measuring the sensor’s capacitance on the sensitivity to H2 have been studied