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Validation of a triangular quantum well model for GaN-based HEMTs used in pH and dipole moment sensing This publication appears in: Journal of Physics D: Applied Physics Authors: S. Rabbaa and J. Stiens Volume: 45 Issue: 47 Number of Pages: 9 Publication Date: Oct. 2012
Abstract: Gallium Nitride (GaN) is a relatively new semiconductor material that has the potential of replacing gallium arsenide (GaAs) in some of the more recent technological applications, for example chemical sensor applications. In this paper we introduce a triangular quantum well model for undoped AlGaN/GaN high electron mobility transistor (HEMT) structure used as chemical and biological sensor for pH and dipole moment measurements of polar liquids. We have carried out theoretical calculations related to the HEMT characteristics and we have compared them with experimental measurements done in many previous papers. These calculations include the current-voltage (I-V) characteristics of the device, the surface potential, the change of the drain current with the dipole moment and the drain current as a function of pH. The results exhibit good agreement with experimental measurements for different polar liquids and electrolyte solutions. It is also found that the drain current of device exhibits a large linear variation with the dipole moment and that the surface potential and the drain current depend strongly on the pH. Therefore, it can distinguish molecules with slightly different dipole moments and solutions with small variations in pH. The ability of the device to sense biomolecules (such as proteins) with very large dipole moments has been investigated.
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