Improvement in pH Sensitivity of Low-Temperature Polycrystalline-Silicon Thin-Film Transistor Sensors Using H2 Sintering

Abstract

Abstract:In this article, we report an improvement in the pH sensitivity of low-temperature polycrystalline-silicon (poly-Si) thin-film transistor (TFT) sensors using an H 2 sintering process. The low-temperature polycrystalline-silicon (LTPS) TFT sensor with H 2 sintering exhibited a high sensitivity than that without H 2 sintering. This result may be due to the resulting increase in the number of Si-OH 2 + and Si-O − bonds due to the incorporation of H in the gate oxide to reduce the dangling silicon bonds and hence create the surface active sites and the resulting increase in the number of chemical reactions at these surface active sites. Moreover, the LTPS TFT sensor device not only offers low cost and a simple fabrication processes, but the technique also can be extended to integrate the sensor into other systems.

Hybrid Silicon Nanowire Devices and Their Functional Diversity

“…Unlike to the theoretical maximum given by Nernst limit, surface imperfections (as well as use of the materials with the lower surface density of OH groups) give, as a result, a usual value of around 30 mV/pH . Distinct strategies attempted to bring the value of this parameter closer to the theoretical limit, such as the patterning of the nanowires in a honeycomb shape, applying a H 2 sintering process to increase the number of surface‐binding sites, the utilization of high‐ k oxide layers like HfO 2 and Al 2 O 3 , their substitution for lipid monolayers, or the immobilization of gold nanoparticles on the nanowire surface to increase the local concentration of hydrogen ions in the vicinity of the nanowire . While the intrinsic sensitivity limit of the oxide layer cannot be increased, it was demonstrated in recent years that it was possible to go above the Nernst limit by making use of dual‐gated devices to get a capacitive amplification effect …”

Liquid–Solid Interface Engineering of Ultrathin and Solution-Processed Indium Oxide-Based Electrolyte-Gated Transistors by Gallium Doping

“…The high sensitivity of EGTs is also a key indicator of pH sensors. In existing EGTs’ studies for pH detection, pH sensitivity typically has a value close to the Nernst limit of 59 mV/pH. − However, for each pH value to be clearly distinguished and applied directly to the monitoring platform, a device with a higher sensitivity is essential.…”