Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications

InN-Based Chemical Sensors 141

© 2011 by Taylor & Francis Group, LLC

HCl and NaOH aqueous solutions, as shown in Figure4.10. The ISFET was rst immersed in the

HCl aqueous solution, and then NaOH was added to change the pH value of the solution from

acid to base. The pH value was in situ monitored by a pH meter (Hanna HI-111) for the compari-

son with the measured I

DS

. The result is in good agreement with that using buffer solutions. The

average current variation is 17.0 µA/pH, corresponding to a current variation ratio of 4.08%.

The gate sensitivity of the bare InN surface to pH changes in the aqueous solution was measured

using the constant ...