Thickness effect of IGZO layer in light-addressable potentiometric sensor

The thickness effect of In-Ga-Zn oxide (IGZO) semiconductor layer is investigated for pH sensing in light-addressable potentiometric sensor (LAPS). pH sensing membrane is 45 nm-thick NbOx, which is directly on IGZO/ITO/glass substrate. The thickness of IGZO layer is determined by time-mode control in reactive rf sputtering. The highest photovoltage and operation frequency can be obtained in the IGZO thickness of 300 nm. pH sensitivity is about 65 mV/pH with ac signal frequency at 1 kHz. For better stability in hysteresis, further investigations on sensing membrane optimization are suggested.