Study on pH sensing properties of RF magnetron sputtered tantalum pentoxide (Ta2O5) thin film

The pH-sensing properties of tantalum pentoxide (Ta
₂
O
₅
) film deposited by RF magnetron reactive sputtering method is demonstrated. The tantalum pentoxide film on silicon wafer samples were characterized by capacitance-voltage (C-V) measurements. The samples were annealed in ambient condition at 400°C for several hours. High frequency C-V measurements were performed on the wafer samples at pH levels of 4, 7 and 10. Results obtained from the C-V measurements showed good linearity in the selected pH range. The pH sensitivity has reached 62mV/pH, which is better than the theoretical Nernst potential.