Surface charge modifications of Silicon nanowires for electronic nano-biosensor applications

초록

Starting from silicon-on-insulator(SOI) wafer with a 40 nm-thick top silicon layer of boron concentration ~ 5 x 1017 cm-3, we fabricated silicon nanowires of varying width(100-300 nm) and length(2-20 m) by using conventional CMOS technology and measured their transport characteristics on each step of the biosensor fabrication processes where the silicon nanowires have oxide-stabilized surface, bare surface, OH-modified surface, amine-modified surface and aldehyde-functionalized surface. The wires with oxide-stabilized surface as a point of reference showed reproducible and systematic behaviors with mobilities ranging from 200 to 500 cm2/Vs and surface charge density 2.5 x 1011 cm-2 depending on wire dimensions. However, significant surface charge densities induced by the various surface modifications were observed ranging from 4.3 x 1011 to 1.7 x 1012 cm-2 and fluctuated with elapsed time. Characteristics of each surface states exhibited different behaviors and their properties are extensively elucidated.