CMOS-compatible silicon nanowire based field-effect pH sensor

A field effect transistor (FET) sensor for pH detection was developed in this paper based on complementary metal oxide semiconductor (CMOS)-compatible semiconducting nanowires. Optical lithography and anisotropic self-stop etching were employed to guarantee low cost batch production for silicon nanowires. Under environment relevant for sensing experiments, the transfer curves of silicon nanowires (SiNW) FET were studied so as to understand the device sensing performance. With this nanofabricated pH sensor, the change in the hydrogen ion concentration of a solution can be detected by the corresponding change in current. Without surface modification of the nanosensor, its current showed nonlinear pH-dependence and the threshold voltage (V_th) shift of about 4 V has been attained over pH 5.0 to 9.0 ranges. The development of a nanoscale sensor offers the possibility of highly parallel labeling and detection of chemical and biological molecules with selective control of individual array elements in a single integrated chip.