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

A study of AlGaN/GaN high electron mobility transistors (HEMTs) was done to assess their implementation as functionalized in situbiosensors [1]. Gallium nitride presents itself as a viable option in sensors which require a high degree of stability in aqueous and biological settings while also being a suitable wide band gap semiconductor for HEMTs [2]. The functionalization of HEMT biosensors bestows high specificity binding groups to the surface enabling characterization of singular biological functions or environmental conditions [3][4]. However, peptide adherence and stability over a given operational cycle are unknown and thus the efficacy and usable lifetime are yet to be determined. 

     Here, GaN based biosensors were fabricated, functionalized, and then tested with simulated solutions in which the HEMT biosensors would be expected to function. AlGaN/GaN HEMTs were grown via MOCVD (Fig. 1) and functionalized via physisorption of recognition peptides. HEMTs were tested in physiologically relevant solutions as well as controlled solution. Analysis was done upon initial peptide binding via AFM, XPS, and IV measurements. This was repeated after environmental exposure was completed over variable periods of time. The results show the stability of the surface over extended cycles along with the benefits associated with the functionalization of the device. The detailed surface and electrical characterization is essential for quality control and integrity of future sensor development based on GaN devices.

References

 

[1]           M.S. Makowski, and A. Ivanisevic, “Molecular analysis of blood with micro/nanoscale field-effect-transistor biosensors,” Small, 7(14)1863 (2011)

[2]           S. Jewett, M.S. Makowski, B. Andrews, M. Manfra, A. Ivanisevic, “Gallium nitride is biocompatible and non-toxic before and after functionalization with peptides,” Acta Biomaterialia, 8(2)728 (2012)

[3]           A. Ramesh, F. Ren and P. Berger, “Towards in vivo biosensors for low-cost protein sensing,” Electronics Letters, 49(7) 450 (2013)

[4]           M.S. Makowski, I. Bryan, R. Collazo, Z. Sitar, A. Ivanisevic, J. Xie, and C. Arellano, “Kinase detection with gallium nitride based high electron mobility          transistors,” Applied Physics Letters, 103(8) (2013)