High-Sensitivity Metal–Semiconductor–Metal Hydrogen Sensors With a Mixture of Pd and $\hbox{SiO}_{2}$ Forming Three-Dimensional Dipoles

Ammonia sensing characteristics of a Pt/AlGaN/GaN Schottky diode

“…While the ammonia concentration is as low as 35 ppm NH 3 /air, a measurable current variation is still observed. The current increases from 5.4 × 10 −9 A (in an air ambience) to 7.6 × 10 −8 A (in 35 ppm NH 3 /air) at the applied voltage of 0.45 V. The current variation is mainly attributed to the formation of hydrogen dipole layer at metal and semiconductor interface [17]. This results in the reduced width depletion region and thus the lowering of the Schottky barrier height [20].…”

“…Subsequently, hydrogen atoms dissociated by Pt metal permeate through the metal bulk to reach the metal-semiconductor (M-S) interface. It is known that hydrogen atoms at the M-S interface could be polarized to form a dipolar layer by the internal electric field [12,17,20]. This leads to the hydrogeninduced Schottky barrier height variation.…”

“…This also provides the benefit of sensing performance. Previous reports of Schottky diode-type gas sensors were mainly focused on hydrogen sensing performance [13][14][15][16][17]. In this work, an interesting Pt/AlGaN/GaN Schottky diode is illustrated to study the ammonia sensing current-voltage (I-V) characteristics for the first time.…”

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

“…Fortunately, various types of semiconductor hydrogen sensors have been reported with fast response, high sensitivity, or low-cost manufacture. They are, for example, metaleoxideesemiconductor (MOS) [2e7], metalesemiconductor (MS) [6e12], metalesemiconductoremetal (MSM) [13,14], and resistive-type hydrogen sensors [15e17]. Although these hydrogen sensors were investigated based on different sensing mechanisms, most of them use palladium (Pd) to absorb hydrogen.…”

A hydrogen sensor based on a metamorphic high electron mobility transistor (MHEMT)

“…III-V compound semiconductor-based materials have attracted much attention. Their intrinsic properties, including large and changeable energy-bandgap, high electron mobility make themselves good candidates for the fabrication of electronic devices in specialized fields [2], for example, high-frequency devices, gas sensors, and light-emitting diode (LED) [3][4][5]. Hydrogen sensors based on Schottky diodes, field-effect transistors, and high electron mobility transistors (HEMTs) were successfully fabricated and investigated [6][7][8][9].…”