Effects of Environmental Exposure on Stability and Conductance Poly-l-lysine Coated AlGaN/GaN High Electron Mobility Transistors

摘要

AlGaN/GaN HEMTs have been shown promise to be used as irt-situ biosensors. An inquiry was done into the stability of physisorption as a method of adhering surface bioactive molecules to the surface of the HEMT gate contacts. Poly-l-lysine (30,000 MW) was used to coat AlGaN/GaN field effect transistors as a representative charged biomolecule for biosensing applications. Coated FETs were then exposed to 1 and 4 hour soaks in DI water at ambient temperature. Atomic force microscopy (AFM) and conductance measurements (Ⅳ) were used to quantify current decay and surface morphology changes. Analysis of the results showed that charged analytes readily adsorbed onto the surface. Upon adsorption an immediate signal decay was observed. The changes after soaking in solution were variable. The results point to the need to develop specific chemistry that will result in stable immobilization of biomolecules onto the device surface. Such stability is necessary for long- term reliable device operation.