High sensing response Pd/GaN hydrogen sensors with a porous-like mixture of Pd and SiO₂

Abstract

A metal-semiconductor-metal Pd/GaN hydrogen sensor with a porous-like mixture of Pd and SiO 2 is investigated. Besides symmetrically bidirectional sensing characteristics with a widespread voltage regime (at least −5-5 V), a high sensing response of 8 × 10 5 (7.7 × 10 6 ) corresponding to a Schottky barrier height variation of 352 (411) meV is obtained in a 4890 ppm H 2 /N 2 ambience at a voltage of −1.5 (−5) V. A highly efficient dissociation of hydrogen molecules due to an enhanced catalytic activity of the mixture explains the improved performance. Furthermore, dynamic responses by alternately switching voltage polarity and introducing and removing hydrogen-containing gases are also included to evaluate the proposed device as a high sensing response and low power sensor.

Unidirectional sensing characteristics of structured Au–GaN–Pt diodes for differential-pair hydrogen sensors

“…Finally AueGaNePt MSM-type hydrogen sensors were implemented by a mesa-isolation process. Similar to the geometric dimension of the MSM sensor in [22], both the finger width of each multi-finger electrode and the spacing between Au-finger and Pt-finger are 50 mm. Besides, the total area of each multi-finger electrode is 2.7 Â 10 À3 cm 2 for sensing hydrogen-containing gases.…”

Sensing properties of resistive-type hydrogen sensors with a Pd–SiO2 thin-film mixture

“…Since the porous-like properties are found in PdeSiO 2 thinfilm mixture, dissociations of hydrogen molecules could be able to occur on the surface and inside the thin-film mixture [25]. Thus a higher dissociation rate and a faster diffusion rate in PdeSiO 2 thin-film mixture are expected when compared to those in pure-Pd thin film.…”

Study of hydrogen detection response time with Pt-gated diodes fabricated on AlGaN/GaN heterostructure

“…Typically, the response time is defined as the interval of time from initial current increase to when the measured signal reaches 90% (t 90 ) of the total change, but response time definitions ending at percentages between 50% (t 50 ) and 70% of the total change have also been employed. [11][12][13][14][15][16][17] Table I summarizes previously reported response times for semiconductor-based hydrogen sensors.…”