In this paper, we propose a highly efficient surface modification strategy on an AlGaN/GaN high electron mobility transistor (HEMT), where ethanolamine (EA) was utilized to functionalize the surface of GaN and provided amphoteric amine groups for probe molecular immobilization for bioassay application. The molecular gated-AlGaN/GaN HEMT was utilized for pH and prostate-specific antigen (PSA) detection to verify its performance as a biosensor. Benefitting from the high coating quality on the GaN surface, the performance of our biosensor is drastically improved compared to other AlGaN/GaN HEMT based pH and PSA biosensors reported before. Our molecular gated-AlGaN/GaN HEMT biosensor has achieved good static electrical performance for pH sensing, such as high sensitivity, good linearity and chemical stability. Moreover, after further immobilization of PSA antibody onto the EA aminated GaN surface, the limit of detection (LOD) for PSA detection is as low as 1 fg mL⁻¹ in PBS buffer, which has reached an at least two orders of magnitude decrease compared to any other AlGaN/GaN HEMT based PSA biosensor reported before. And the sensitivity of our PSA biosensor has achieved a substantial increase, reaching up to 2.04% for 100 ng mL⁻¹. The measurements of pH and PSA utilizing the EA modified AlGaN/GaN HEMT biosensor indicate that the surface modification strategy on the GaN proposed in this paper can effectively improve the performance of the AlGaN/GaN HEMT based biosensor, which demonstrates a promising application prospect in the AlGaN/GaN HEMT based biological detection field.

This paper presents a preliminary result about ultra-deep etched microstructures on 〈1 0 0〉 silicon wafer based on metal assisted chemical etching (MaCE). Honeycomb hole arrays with 50 µ m width were successfully etched, as deep as 280 µ m. The porous defects on the patterned surface and the lateral etching on the sidewall were effectively suppressed by optimizing the etchant solution. The results in this paper indicate that 〈1 0 0〉 silicon can be etched vertically with smooth sidewalls by an etchant solution containing ethanol, instead of the conventional aqueous-based solution. This improved method of MaCE has potential application in large-scale Si etching as a supplementary method to the expensive and complicated dry etching method.

In this report, we have developed a high sensitivity zinc ion (Zn ²⁺ ) detection method based on a Schiff base functionalized extended gate (EG)-AlGaN/GaN high electron mobility (HEMT) sensor.

In this study, we propose a differential extended gate (DEG)-AlGaN/GaN high electron mobility transistor (HEMT) sensor to detect ionic pollutants in solution. The DEG-AlGaN/GaN HEMT sensor consists of two extended gate sensing units, which combine the differential method with the extended gate structure. Ionic pollutant Fe³⁺ is used to test the feasibility of the device. Compared to the conventional AlGaN/GaN HEMT sensor, DEG-AlGaN/GaN HEMT sensors can effectively reduce the effect of noise factors and successfully improve the detection limit to 10 fM. At the same time, the DEG sensor shows that Fe³⁺ can be detected in a wide range of concentrations, varying from 10 fM to 100 μM, and it shows better linearity (R² = 0.9955) than the conventional AlGaN/GaN HEMT sensor. These results demonstrate that the unique DEG design can overcome the drawbacks of the conventional AlGaN/GaN HEMT sensor, and significantly improve the overall performance of the AlGaN/GaN HEMT sensor. As a result, this novel sensor has the potential to be a real-time and high-performance test tool for environmental monitoring.