Devices based on series-connected Schottky junctions and β-Ga<sub>2</sub>O<sub>3</sub>/SiC heterojunctions characterized as hydrogen sensors

Abstract

Abstract. Field-effect hydrogen gas sensor devices were fabricated with the structure of a series connection between Schottky junctions and β-Ga2O3/6H-SiC heterojunctions. β-Ga2O3 thin films were deposited on n-type and p-type 6H-SiC substrates by gallium evaporation in oxygen plasma. These devices have rectifying properties and were characterized as hydrogen sensors by a Pt electrode. The hydrogen-sensing properties of both devices were measured in the range of 300–500 °C. The Pt/Ga2O3/n-SiC device revealed hydrogen-sensing properties as conventional Schottky diode-type devices. The forward current of the Pt/Ga2O3/p-SiC device was significantly increased under exposure to hydrogen. The behaviors of hydrogen sensing of the devices were explained using band diagrams of the Pt/Ga2O3/SiC structure biased in the forward and reverse directions.

Synthesis and CO gas sensing properties of surface-nitridated Ga2O3 nanowires

“…5 A small amount of SnO 2 incorporation into Ga 2 O 3 is known to increase the electrical conductivity and improve the CO and CH 4 gas sensitivity. 8 Recently, Nakagomi et al reported that the forward current was signicantly increased upon exposure to hydrogen without showing the sensitivity, 9 but there is no report on CO gas detection using Ga 2 O 3 -based Schottky diode sensors. The hydrogen sensing properties were measured in the range of 300-500 C. Trinch et al (2004) proposed a sensor with Pt/Ga 2 O 3 /SiC structure for the rst time and demonstrated hydrogen sensing properties due to a change in Schottky barrier height.…”

“…The hydrogen sensing properties were measured in the range of 300-500 C. Trinch et al (2004) proposed a sensor with Pt/Ga 2 O 3 /SiC structure for the rst time and demonstrated hydrogen sensing properties due to a change in Schottky barrier height. 8 Recently, Nakagomi et al reported that the forward current was signicantly increased upon exposure to hydrogen without showing the sensitivity, 9 but there is no report on CO gas detection using Ga 2 O 3 -based Schottky diode sensors. The drawbacks of Schottky diode sensors are the relatively low reverse voltage ratings for silicon-metal Schottky diodes, and thermal instability due to a relatively high reverse leakage current.…”

Synthesis of Wide Bandgap β-Ga2O3 Rods on 3C-SiC-on-Si

“…Also it has isotropic and higher electron Hall mobility compared to that of 6H-SiC . Synthesis of Ga 2 O 3 thin layers on 6H-SiC substrates by gallium evaporation in oxygen plasma and the sol–gel technique has been reported previously. − Gas sensors based on Ga 2 O 3 /SiC heterojunction have been fabricated previously. − In addition, because of the current difficulty associated with p-type doping of Ga 2 O 3 , a heterojunction photodetector device comprised of n-type Ga 2 O 3 and p-type SiC has been reported . Furthermore, by using semiconducting SiC as the growth substrate instead of insulating materials such as sapphire, vertical electrical-injection devices can be directly fabricated.…”

Forward Current Conduction Mechanism of Mechanically Exfoliated β-Ga2O3/GaN pn Heterojunction Diode

“…Among the five different phases of gallium oxide, the monoclinic beta-phase gallium oxide (β-Ga 2 O 3 ) has attracted a lot of interest for being suitable for high voltage, high power electronic device [1][2][3][4][5] and deep ultraviolet detector [6][7][8][9] applications, owing to the wide bandgap (E G ) of 4.8-4.9 eV, in comparison with SiC of 3.2 eV and GaN of 3.4 eV, respectively, 10 and the resulting theoretical breakdown electric field up to 8 MV cm −1 , 11 in addition to the large size, high-quality and low cost single crystalline β-Ga 2 O 3 substrates synthesized by conventional melt growth methods, such as Czochralski, floating zone or edge-defined film-fed growth. [12][13][14][15] Furthermore, a large lattice constant of 12.23 Å along [100] direction renders the facile cleavage of β-Ga 2 O 3 crystal into thin belts or nano-membranes possible.…”