Effect of microwave-assisted silanization on sensing properties of silicon nanoribbon FETs
2015 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, Vol. 209, 586-595 p.Article in journal (Refereed) Published
An important concern with using silicon nanoribbon field-effect transistors (SiNR FET) for ion-sensing is the pH-response of the gate oxide surface. Depending on the application of the FET sensor, this response has to be chemically manipulated. Thus in silicon oxide-gated pH-sensors with integrated sensor and reference FETS, a surface with high pH-sensitivity, compared to the bare gate oxide, is required in the sensor FETs (SEFET), whereas in the reference FETs (REFET) the surface has to be relatively pH-insensitive. In order to control the sensitivity and chemistry of the oxide surface of the nanoribbons, a silanization reagent with a functional group is often self-assembled on the SiNR surface. Choice of a silanization reaction that results in a self-assembled layer on a silicon oxide surface has been studied extensively over the past decades. However, the effect of various self-assembled layers such as monolayers or mixed layers on the electrical response of SiNR FETs in aqueous solution needs to be exploited further, especially for future integrated SEFET/REFET systems. In this work, we have performed a comprehensive study on 3-aminopropyltriethoxysilane (APTES) silanization of silicon oxide surfaces using microwave (MW) heating as a new biocompatible route to conventional methods. A set of complementary surface characterization techniques (ellipsometry, AFM and ATR-FTIR) was used to analyze the properties of the APTES layer deposited on the silicon surface. We have found that a uniform monolayer can be achieved within 10 min by heating the silanization solution to 75 degrees C using MW heating. Furthermore, electrical measurements suggest that little change in device performance is observed after exposure to MW irradiation. Real-time pH measurements indicate that a uniform APTES monolayer not only reduces the pH sensitivity of SiNR FET by passivating the surface silanol groups, but also makes the device less sensitive to cation concentration in the background electrolyte. Our silanization route proves promising for future chemical surface modification of on-chip REFETs.
Place, publisher, year, edition, pages
2015. Vol. 209, 586-595 p.
Silicon nanoribbon field-effect transistors, Microwave heating, Silanization, Surface characterization, Electrical measurements, pH sensitivity
IdentifiersURN: urn:nbn:se:kth:diva-161089DOI: 10.1016/j.snb.2014.12.030ISI: 000349082200077ScopusID: 2-s2.0-84919754424OAI: oai:DiVA.org:kth-161089DiVA: diva2:796167
FunderVINNOVAKnut and Alice Wallenberg Foundation
QC 201503182015-03-182015-03-092016-08-25Bibliographically approved