Room temperature ppt-level NO₂ gas sensor based on SnO _x/SnS nanostructures with rich oxygen vacancies

In this paper, tin oxidation (SnO x )/tin-sulfide (SnS) heterostructures are synthesized by the post-oxidation of liquid-phase exfoliated SnS nanosheets in air. We comparatively analyzed the NO2 gas response of samples with different oxidation levels to study the gas sensing mechanisms. The results show that the samples oxidized at 325 °C are...

Enhanced Sensitivity Pt/AlGaN/GaN Heterostructure NO Sensor Using a Two-Step Gate Recess Technique

Based on our proposed precision two-step gate recess technique, a suspended gate-recessed Pt/AlGaN/GaN heterostructure gas sensor integrated with a micro-heater is fabricated and characterized. The controllable two-step gate recess etching method, which includes O2 plasma oxidation of nitride and wet etching, improves gas sensing performance....

The Impact of Gate Recess on the H2 Detection Properties of Pt-AlGaN/GaN HEMT Sensors

The present work reports on the hydrogen gas detection properties of Pt-AlGaN/GaN high electron mobility transistor (HEMT) sensors with recessed gate structure. Devices with gate recess depths from 5 to 15 nm were fabricated using a precision cyclic etching method, examined with AFM, STEM and EDS, and tested towards H 2 response at high...

The Impact of Gate Recess on the H₂ Detection Properties of Pt-AlGaN/GaN HEMT Sensors

The present work reports on the hydrogen gas detection properties of Pt-AlGaN/GaN high electron mobility transistor (HEMT) sensors with recessed gate structure. Devices with gate recess depths from 5 to 15 nm were fabricated using a precision cyclic etching method, examined with AFM, STEM and EDS, and tested towards H2 response at high...

AlGaN/GaN high electron mobility transistor (HEMT) based sensors for gas sensing applications

The rapid development and market growth of microelectronics technology continues to provide expanding connectivity, productivity, entertainment and well-being to billions of users globally. Moreover, continuous demand for more on-chip functionally presents an exciting opportunity for integration of various chemical sensors for monitoring...

Suspended AlGaN/GaN HEMT NO₂ Gas Sensor Integrated with Micro-heater

We developed an AlGaN/GaN high electron mobility transistor (HEMT) sensor with a tungsten trioxide (WO₃) nano-film modified gate for nitrogen dioxide (NO₂) detection. The device has a suspended circular membrane structure and an integrated micro-heater. The thermal characteristic of the Platinum (Pt) micro-heater and the...

Impact of high temperature H₂ pre-treatment on Pt-AlGaN/GaN HEMT sensor for H₂S detection

In this paper, a method to extend the detection range of hydrogen sulfide (H₂S) gas sensor is demonstrated. The sensor is based on AlGaN/GaN high electron mobility transistors (HEMTs) with Pt gate. It is observed that the as-fabricated devices exhibited sensing signal saturation at 30 ppm H₂S exposure in dry air. A pre...

Characterization of an Acetone Detector based on a Suspended WO3-Gate AlGaN/GaN HEMT Integrated with Micro-heater

A suspended AlGaN/GaN high electron mobility transistor (HEMT) sensor with a tungsten trioxide (WO 3 ) nanofilm modified gate was microfabricated and characterized for ppm-level acetone gas detection. The sensor featured a suspended circular membrane structure and an integrated microheater to select the optimum working temperature. High working...

AlGaN/GaN HEMT micro-sensor technology for gas sensing applications

Wide bandgap gallium nitride material has highly favorable electronic properties for next generation power and high frequency electronic devices. A less widely studied application is highly miniaturized chemical and gas sensors capable of operating in harsh environment conditions. In this work we present our recent developments on design,...

Hydrogen sulfide detection properties of Pt-gated AlGaN/GaN HEMT-sensor

AlGaN/GaN high electron mobility transistor (HEMT)-based sensors with catalytic platinum gate were micro-fabricated on commercially available epitaxial wafers and extensively characterized for ppm level hydrogen sulfide (H₂S) detection for industrial safety applications. High operating temperature above 150 °C enabled large signal...

Pt-AlGaN/GaN HEMT-sensor layout optimization for enhancement of hydrogen detection

This paper reports on the layout optimization of Pt-AlGaN/GaN HEMT-sensors for enhancing hydrogen sensor performance. Sensors with gate width and length ratios W_g/L_g from 0.25 to 10 were designed, fabricated and tested for the detection of hydrogen gas at 200 °C. Sensitivity, sensing current variation and transient...

Precision Recess of AlGaN/GaN with Controllable Etching Rate Using ICP-RIE Oxidation and Wet Etching

A method for highly controllable etching of AlGaN/GaN for the fabrication of high sensitivity HEMT based sensors is developed. The process consists of cyclic oxidation of nitride with O₂ plasma using ICP-RIE etcher followed by wet etching of the oxidized layer. Previously reported cyclic oxidation-based GaN etching obtained very...