CVD single layer graphene for chemo-resistor pH sensors

Abstract

Graphene has been deposited using low-pressure chemical vapor deposition (LPCVD) on metallic substrates (nickel and copper foils) under different deposition times gas mixtures and temperatures Optical microscopy Raman spectroscopy scanning electron microscopy X-ray photoelectron spectroscopy and atomic force microscopy were used to investigate the characteristics of the obtained graphene For chemo-resistor pH sensor fabrication two gold electrodes were deposited on Si/SiO2 substrates using a thermal evaporation method The different graphene films were then transferred onto the gold-deposited substrate for use as the sensor Buffer solutions having pH values varying from 4 to 11 were used The highest sensitivity of the sensor is 1 92 kΩ pH-1 Also two ways fabricated nitrogen-doped graphene: post growth doping on copper foils and doping after transfer with the assistance of ammonia The crystallinity and properties of graphene were changed by the different amount of nitrogen doped The nitrogen-doped graphene samples applied for chemo-resistor pH sensors as the sensing layers showed remarkable properties Due to the simple structure and chemical stability chemo-resistor sensor based on graphene and nitrogen-doped graphene is a highly promising candidate for micro and nanoscale applications

Date of Award	2017 Aug 16
Original language	English
Supervisor	Jyh-Ming Ting (Supervisor)