Applications of AlGaN/GaN high electron mobility transistor-based sensors in water quality monitoring

Abstract

AlGaN/GaN high electron mobility transistors (HEMTs) have demonstrated their extraordinary potential in developing solid-state microsensors for detecting gases, metal ions, anions, biomolecules, and other substances due to their excellent chemical stability, high surface charge sensitivity, high temperature-tolerance performance, and low power consumption characteristics. In this paper, only three types of AlGaN/GaN HEMT-based sensors used for detecting the pH value, heavy metal ions, and harmful anions, which are suitable for water quality monitoring, will be discussed. First, we introduce the structural design, detection principle, and fabrication processes of AlGaN/GaN HEMT-based sensors. Then, surface functionalization methods for the gate region, sensing mechanisms, and the sensitivity and selectivity performances based on different gate region treatments are reviewed and analyzed. Finally, some challenging problems that hinder the practical application of the sensors are proposed.

Advancements in tunable and multifunctional metamaterial absorbers: a comprehensive review of microwave to terahertz frequency range

“…In addition, diodes made of silicon as a representative generation of semiconductor materials are more serious in high temperature environments, thus limiting their application range [126,127]. As a third-generation semiconductor material, gallium nitride has the advantages of high electron mobility, high working bandwidth, short response time and high temperature resistance, which has great development potential [128,129]. Diodes or gallium nitride high electron mobility transistors (GaN HEMTs) made from gallium nitride materials have high application value in metamaterials.…”

A Review on Gallium Nitride for Liquid Sensors: Fabrications to Applications

“…28 To maintain charge neutrality within the undoped AlGaN/GaN heterostructure, the negative sheet charge of the 2DEG has to be balanced by positive adsorbed charges at the heterostructure surface. 25 A decrease in the positive surface charge resulting from the adsorption of negative ions is expected to lead to a reduction in the 2DEG sheet carrier concentration and a consequent rise in the sheet resistance of the device and conversely. Consequently, GaN lateral-transistor-based sensors demonstrate remarkable sensitivity to polar liquids and offer superior performance compared to their silicon counterparts in terms of sensitivity, rapid response time, durability, and ability to operate effectively at elevated temperatures.…”

Status and Prospects of Heterojunction-Based HEMT for Next-Generation Biosensors

“…The fabrication cost of heterojunction-based HEMT biosensors is the elephant in the room, hindering the sensor market’s breakthrough. In contrast to Si technology, heterojunction-based HEMT devices are still in their infancy [ 177 ]. Inexpensive disposable biosensor chips are still in demand on the market, whereas the currently available sensors on the market are still unfavourable due to their limitations and problems with false positives.…”