Investigating thin film passivations for IGZO dual gate pH sensors fabricated at low temperature

Dual-gate IGZO TFTs fabricated using high-k dielectrics deposited via ALD at low temperature (<; 180°C) are proposed for chemical and biosensor applications, leading to an investigation of suitable passivation films for such devices. Both PECVD and ALD films are considered for the passivation layer, which also serves as the liquid sensing gate, and it is found that ALD TiO
₂
offers a sensitivity of 76 mV/pH, which is beyond the Nernst limit found in traditional ISFET sensors.