Advanced gallium nitride high electron mobility transistors for biosensing applications: Progress, challenges, and future perspectives

Abstract

GaN High Electron Mobility Transistors represent a breakthrough technology for biosensing applications, offering exceptional sensitivity through their unique two-dimensional electron gas channel positioned close to the sensing surface. This comprehensive review provides the first systematic analysis of the complete GaN HEMT biosensor ecosystem, distinguishing itself from previous reviews through: (i) Comprehensive coverage of emerging architectural innovations including novel heterostructures, dimensional variants, and advanced gate engineering approaches; (ii) Detailed analysis of MOS-HEMT configurations and their superior performance in physiological media; and (iii) Critical assessment of commercialization challenges and practical implementation strategies. The fundamental advantage of GaN HEMTs lies in their ability to detect minute charge variations from biomolecular interactions with detection limits reaching attomolar concentrations, enabled by the 2DEG channel's proximity (20–30 nm) to the sensing surface. The review systematically examines device architectures ranging from conventional AlGaN/GaN structures to advanced MOS-HEMT designs with dielectric layers that provide 2–3× sensitivity enhancement while improving stability in high ionic strength media. Novel heterostructures including InAlN/GaN systems and N-polar configurations offer up to 4× sensitivity improvements compared to conventional designs. Different gate engineering approaches are analyzed, encompassing dual-gate architectures for differential sensing, recessed designs for enhanced control, and extended-gate configurations for harsh environments.

This review uniquely addresses the critical interface between device physics and practical biosensing through comprehensive analysis of surface functionalization strategies, charge screening mitigation techniques, and biocompatibility considerations. Current limitations including signal drift (0.1–2.0 mV/h), selectivity challenges in complex biological matrices, and manufacturing reproducibility (5–15 % coefficient of variation) are critically evaluated alongside emerging solutions involving differential measurements, anti-fouling surface modifications, and machine learning algorithms. Future developments focus on transformative trends not comprehensively covered in previous reviews: self-powered sensors with integrated energy harvesting, multi-modal detection platforms combining optical and electrochemical sensing, IoT-connected monitoring networks for population-level healthcare, and expanding environmental monitoring applications. These advances position GaN HEMT biosensors as enabling technologies for next-generation healthcare diagnostics, environmental monitoring, and smart sensing ecosystems.