Sensitivity of the a-C:H gate pH-ISFET

The hydrogenated amorphous carbon (a-C:H) contains significant fractions of sp3 type C bondings, giving them attractive physical and mechanical properties, some similar to a certain extent to the diamond. Otherwise, the dielectric constant of the a-C:H films covers the range of 2.5 - 6, and the a-C:H also can be used for the protective and isolated layer. In this paper, we study the sensitivity of the a-C:H applied to the pH-ISFET (ion sensitive field effect transistor). The a- C:H gate pH-ISFET devices were prepared by the plasma-enhanced low pressure chemical vapor deposition (PE-LPCVD). The sensitivity is determined by the IDS - VGS and C-V curves shift in the various pH buffer solutions. We can also measure the pH at zero charge point (pHpzc) for the a-C:H gate pH-ISFET.