Study of hydrogen-sensing characteristics of a Pt-oxide-AlGaAs metal-oxide-semiconductor high electron mobility transistor

Abstract

A new hydrogen sensor based on a GaAs-based high electron mobility transistor (HEMT) with a catalytic Pt-oxide-Al0.24Ga0.76As (MOS) gate structure is fabricated and demonstrated. The threshold voltage shift, hydrogen detection sensitivity, and transient responses of the device under different hydrogen concentrations and temperature are measured and studied. Based on the transistor amplification action, even at an extremely low hydrogen concentration of 14ppm H2/air, the studied device shows significant drain current variation (about 0.12mA). Furthermore, the studied device can be operated under wider operating temperature regimes with remarkable hydrogen-sensing properties. The decreased hydrogen detection capability with increasing operating temperature demonstrates the exothermic reaction of the hydrogen adsorption and desorption processes.

On a Pd/InAlAs metamorphic high electron mobility transistor (MHEMT)-based hydrogen sensor

“…The response time a is decreased with increasing the hydrogen concentration and temperature. The results are well consistent with previous report [17]. It is worth to note that the response time shows less dependence on the temperature as exposing to high-concentration hydrogen gases i.e., the temperature effect dominates the response time of the studied device as exposing to low-concentration hydrogen gases.…”

“…It is known that high electron mobility transistor (HEMT)-type hydrogen sensors present the advantages of large current variation, fast response, and the compatibility with conventional semiconductor fabrication process [16]. Previously reported FET-type sensors, including GaAs-and AlGaAs-HEMTs, demonstrated good sensing properties toward hydrogen gas [16,17]. Although these hydrogen sensors exhibit good sensing performance, the electron mobility of those devices is not as high as those with high indium contents at the channel layer [18].…”

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

“…Therefore, dense Pd metal film is preferred, especially for those semiconductor device-based hydrogen sensors. The transistor-type sensors, on the contrary, exhibit high sensing capability even though the dense Pd metal is used as the sensing material [14]. This is mainly attributed to the amplification behavior of a transistor.…”

Platinum Coating on an Ultrathin InN Epilayer as a Dual Gas Sensor for Selective Sensing of Ammonia and Acetone by Temperature Modulation for Liver Malfunction and Diabetes Applications

“…This is because when ammonia and acetone are exposed on a −10 nm Pt-atop InN epilayer, ammonia and acetone are adsorbed at adsorption sites and dissociated into hydrogen atoms at the surface of a thin Pt catalytic metal film. [40][41][42][43][44] Further, part of the dissociated hydrogen atoms diffuse and are trapped at the interface of Pt catalytic metal and InN epilayer to form the dipole layer at the interface. 45 This leads to change the conductivity of the InN epilayer.…”

“…Therefore, the modulation of the electron accumulation at an InN epilayer is much higher because the Pt film is in direct contact with the InN film. 16,19,40,[49][50][51][52][53][54][55] The following reaction will take the place of ammonia and acetone gas adsorption on the Pt-coated InN layer in an air background. The reaction mechanism of NH 3 in an air background is given by Equation 7.…”