| AVS 57th International Symposium & Exhibition | |
| Biomaterial Interfaces | Friday Sessions |
| Session BI+MN-FrM |
| Session: | Sensors & Fluidics for Biomedical Applications |
| Presenter: | O. Seitz, University of Texas at Dallas |
| Authors: | O. Seitz, University of Texas at Dallas P.G. Fernandes, University of Texas at Dallas H.C. Wen, Texas Instruments, Inc. H.J. Stiegler, University of Texas at Dallas R.A. Chapman, University of Texas at Dallas E.M. Vogel, University of Texas at Dallas Y.J. Chabal, University of Texas at Dallas |
| Correspondent: | Click to Email |
There is currently a strong need to develop sensitive and reliable biosensors, based on electronic detection, such as field-effect transistors (FET). Most of the focus has been on improving sensitivity by decreasing the FET channel size, using nanowires instead of similar devices on planar silicon. Issues of silicon functionalization, important for device reliability have been mostly ignored.
In this work, we present a robust approach to functionalize the channel region of a SOI wafer, thus achieving better reliability and sensitivity to very low analyte concentrations. The process leads to attachment of active SAM on oxide-free (H-terminated) silicon through formation of a Si-C bond on the channel. Combining IR absorption (IRAS) and X-ray photoelectron (XPS) spectroscopies, photoluminescence, atomic force microscopy (AFM) and electrical measurements, we find that this configuration results in a stable device where the active SAM is more strongly attached to the Si than silane molecules do on oxides. This functionalization is achieved by immersion in carboxylic acid (COOH)-terminated alkene molecules to functionalize the H-terminated channel. After processing, XPS and IRAS confirm that the channel remains oxide-free, that the packing of the SAM on the channel is dense. Photoluminescence measurements confirm the high quality of the interface on the channel where non-radiative recombination (interface states) is not detected. The AFM pictures confirm that active molecules attach to the channel (imaged by attachment of nanoparticles). Electrical measurements, on these improved devices, indicate excellent response for both pH and protein sensing with sensitivity at least as good as the one of similar structure with a uniform SAM functionalization (i.e. using oxidized Si channels).