Fabrication and characterization of undoped polysilicon nanowire for pH sensor

Abstract

Polysilicon has great benefit in application of pH sensor due to the unique properties and easiness to use top-down approach. In this paper, we present fabrication and characterization of undoped polysilicon nanowire (NW) for pH sensor application. The fabrication processes steps involve were photolithography, etching, deposition and oxidation. 3-aminopropyltriethoxysilane or APTES were used to enhance the sensitivity of polysilicon layer as well as able to provide surface modification by undergoing protonation and deprotonation process. Surface analysis using SEM were used for surface morphology analysis. Different types of pH solution provide different resistivity and conductivity towards polysilicon surface. In addition, voltage, current, conductance against pH level are characterized and compared. Alkaline solution has the higher current as compared to acidic. This was due to the polysilicon layer contains more holes which are easily being attracted bySiO¯ to the surface and hence, forming a strong channel from source to drain. Results obtain reveal a linearity of pH measurement with a corresponding sensitivity of 4.65 nS/pH.

Investigation of pH Effect on the Performance of Undoped Silicon Carbide Nanowire Field-Effect Transistors for the Development of Chemical Sensors and Biosensors

“…These available sites have the capability to either accept hydrogen ions by adsorption mechanism or release them in a dynamic exchange process according to the description of the binding site model. 20 The pH response is determined by the interaction of the surface silanol (SiOH) group produced from the hydrolysis of SiO 2 2,21 with the H + ions. This interaction can be briefly explained by two main processes, namely protonation (addition of cations) and deprotonation (removal of cations).…”

“…For instance, the fabrication and characterization of undoped polysilicon nanowire as a pH sensor was reported. 2 The work demonstrated that variation in pH from pH 2 to pH 12 results in the reduction of current by 1.2 times due to the higher concentration of OHand deprotonation of SiOH groups. Similar work was done by the same group of researchers on doped polysilicon nanowire as a biosensor showing opposite trends in current of the undoped nanowire for the same ranges of pH.…”

“…Nanostructured materials have been extensively studied for the past two decades due to their interesting and unique thermal, electronic, mechanical, and optical properties. [1][2][3] Nanostructured materials with their high surface-to-volume ratio, single crystallinity, and high sensitivity have led to an explosion of utilization of these materials in a variety of sensing applications such as medical, biochemical, and food inspection. [4][5][6] In recent years, a tremendous amount of progress has been made in the field of one-dimensional semiconductor nanostructures.…”

“…12 Thus, capability to perform in harsh conditions make SiC an attractive candidate for pH sensors to be used in a wide range of applications such as monitoring of environmental and chemical processes, manufacturing, processing of food, and supporting basic research. 2,13,14 Until now, only a few groups have studied the effect of pH on semiconductor materials. For instance, the fabrication and characterization of undoped polysilicon nanowire as a pH sensor was reported.…”