Capacitance Electrochemical pH Sensor Based on Different Hafnium Dioxide (HfO2) Thicknesses

Over the past years, to achieve better sensing performance, hafnium dioxide (HfO2) has been studied as an ion-sensitive layer. In this work, thin layers of were used pH-sensitive membranes and deposited by atomic layer deposition (ALD) process onto electrolytic-insulating-semiconductor structure Al/Si/SiO2/HfO2 for realization a pH sensor. The thicknesses HfO2 in work was 15, 19.5 39.9 nm. thickness controlled ALD during fabrication process. sensitivity toward H+ clearly higher when compared other interfering ions such potassium K+, lithium Li+, sodium Na+ ions. Mott?Schottky electrochemical impedance spectroscopy (EIS) analyses characterise investigate sensitivity. This recorded Mott–Schottky at 54.5, 51.1 49.2 mV/pH EIS 5.86 p[H?1], 10.63 12.72 p[H?1] 30 nm sensitive layer, respectively. developed sensor highly selective three thicknesses, nm, HfO2-sensitive previously mentioned interferences. However, performances with 15 technique, whilst analyses, sensors more thickness.