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AlGaN/GaN high electron mobility transistor (HEMT) biosensors have garnered significant attention due to their highly sensitive two-dimensional electron gas (2DEG) channel. Open-gate HEMT structure is commonly employed, utilizing various sensing membranes with different deposition methods. Gold nanostructures are effective sensing membranes that can serve as both sensing elements and biosensor linkers. Despite their potential, there has been limited research on modifying the HEMT sensing membrane with gold nanostructures. Herein, the gold nanoislands (AuNis) have been employed as a sensing membrane on the AlGaN/GaN HEMT for the first time for pH detection, which involves a straightforward fabrication process and is cost-effective. To validate the effectiveness of AuNis on the AlGaN surface, a simulation model was employed, demonstrating that the presence of AuNis contributes to a modest increase in both electron concentration and carrier density within the 2DEG channel. The sensor features a high voltage sensitivity of 52.57 mV/pH, a current sensitivity of 67.81 µA/pH, and a small hysteresis value of 2.09 µA in wide pH ranges (pH 2 to pH 12). It displays outstanding stability and reliability, with the lowest coefficient of variation (C.V.) of 0.04 % and no discernible difference after 333 days, respectively. The AuNis structure provides a large surface area, enhancing the H+ ion diffusion rate onto the AlGaN layer accordingly, allowing for a rapid response time of 7 s. Our findings pave the way for a new sensing approach for the next biosensors’ generation.

Pour en savoir plus : Exceptional reliability and stability AuNis–AlGaN/GaN HEMT sensor for pH detection