Novel, highly sensitive Si-NWs with the length of 200μm, with size of 15nm were fabricated using basic standard CMOS processes, Reactive ion etching (RIE) and Buffered Oxide Etching (BOE). FESEM micrograph was used to observe the defining and trimming results. With this process, the width of the wires is decreased from the initial, larger 1μm dimensions to approximately 15nm in a controllable and convenient way. The device is pre-treated with higher pH DI for the mobile carriers to be accumulated at the inner surface of silicon nanowire and nine standard aqueous pH buffer solutions: pH2, pH3, pH 4, pH 5, pH6, pH8 and pH9 were used to test the electrical response of the device. The SiNWs sensor show the highest resistance value for pH 2 and the lowest resistance value for pH 9. In terms of sensitivity, the device with smaller nanowire is found to be more sensitive than larger nanowire as a result of the high surface-to-volume ratio and the measurements were done for 5 times on each sample in 24 hours after the nanowire sensor is immersed in DI water overnight (∼24hours), the pH sensitivity is reproduced at every internal. This tendency is repeated in for all the samples. Hence, the fabricated device has demonstrated the potential device in the pH level detection.
