Room-Temperature Hydrogen Sensitivity of a MIS-Structure Based on the$hboxPt/LaF_3$Interface

Abstract

An LaF 3 layer was shown to improve the characteristics of field-effect gas sensors for room-temperature hydrogen monitoring. The Pt/LaF 3 interface leads to a Nernst-type response and a detection limit of 10-ppm hydrogen in atmospheric air. The response time was shown to be about 110 s and was independent of hydrogen concentration. A method for the stabilization of a long-term behavior of the sensor was successfully demonstrated. The mechanism of the sensor's response to hydrogen was shown to be different from that of the metal/insulator/semiconductor (MIS)-type sensors.Index Terms-Hydrogen sensor, metal/insulator/semiconductor (MIS) structure, room-temperature measurement, solid electrolyte.

The $\hbox{Pd/TiO}_{2}$/ $\hbox{n}$-LTPS Thin-Film Schottky Diode on Glass Substrate for Hydrogen Sensing Applications

“…The τ res is decreased with increasing hydrogen concentration, e.g., it decreases from 40 s for 50 ppm to 17 s for 8000 ppm. These response times are less than or comparable with the reported one in Si [30] or in III-V compound [31] H 2 sensor. In addition, as shown in the inset, the relationship between the sensing current and hydrogen concentration is almost linear in steady state for the hydrogen concentration that is less than 800 ppm.…”

“…All of the response curves rise very rapidly under the introduction of H 2 /air gas (H 2 /air on). Based on these curves, the response time (τ res ) defined as the time for the current from the initial value to 90% of the final steady-state value [30] can be extracted and is also listed in the figure. The τ res is decreased with increasing hydrogen concentration, e.g., it decreases from 40 s for 50 ppm to 17 s for 8000 ppm.…”

Improving hydrogen detecting performance of a Pd/n-LTPS/glass thin film Schottky diode with a TiO2 interface layer

“…We attribute the quicker response times ( res ) of MIS to the wider barrier height modulation ( ˚B) [12,13,21]. The 40 s response time is fast or comparable to the reported values of 110 s for a Si field effect structure sensor to 50 ppm H 2 in air [19] and of 27 min for III-V compound to 48 ppm H 2 in air [30]. The S r values for the developed MS and MIS Schottky barriers biased at −2 V and at room temperature are shown in Fig.…”

“…Under the conditions of room temperature and −2 V bias, the MIS Schottky diode has a relative sensitivity ratio of S r = 3504% and a response time of res = 17 s to 8000 ppm of H 2 in air, which are better than those for the MS counterpart (S r = 331.5% and res = 24 s). The S r is defined as S r = ((I H 2 − I air )/I air ) × 100% [11], where I H 2 and I air are currents measured in hydrogen and air atmospheres, respectively, and res as the time for the current to change from its initial value to 90% of the final steady state value [19]. Furthermore, the S r of the MIS Schottky diode is larger or comparable to the values of 10 2 -10 3 % to 154 ppm H 2 in N 2 reported for the sensors based on Si [10] or of ∼2600% to 1000 ppm H 2 in air for a III-V compound [11].…”

Field-effect hydrogen sensor device with floating gate exhibiting unique behavior

“…Room temperature operation is also an important demand for lowering power consumption and improving safety. Several studies have reported on room-temperature operation of field-effect gas sensors [5][6][7][8]. Gergintschew et al have tried room-temperature sensing of H 2 using a capacitive-controlled FET [5].…”