| Summary: | 碩士 === 國立清華大學 === 奈米工程與微系統研究所 === 96 === pH is a familiar noun in our daily life, it represents the concentration of hydrogen ion in a solution, the lower pH value means higher hydrogen ion concentration. pH value is significantly effective in many fields, such as biology, chemistry, agriculture and so on. The measurement of pH value is an important topic.
An intrinsic surface electron accumulation layer is existed in indium nitride. The surface electron concentration is sensitive to the variation of environment. In order to bring surface electron in to full play, ultra thin InN film (~10nm) was used in this study. The pH sensor was realized by the form of Ion Sensitive Field Effect Transistor (ISFET). In the range of pH value 2 to 10, there is Nernst response 58.33mv/pH, which is very close to the theoretical value 59.16mv/pH calculated by Nernst equation.
When operated in current mode and applied voltage 0.5V, the current variation was 37uA per pH, which is one order higher than the ISFET made by AlGaN/GaN heterostructure. It’s resulted from the property of surface electron accumulation.
Many important performance factor of sensor was investigated, such as response time, detection limit, precision, etc.
Finally, by the way of negative charged Au nanoparticles detection, it shows the potential to detect other charged particles or molecules.
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