A modified TCAD simulation model for a-InGaZnO based ISFETs on GaAs substrate for pH sensing applications

Abstract

Abstract In this paper, an ISFET model is established and its accuracy is verified. The model can overcome the limitation of TCAD of not supporting electrolyte solution simulation. The source and drain of the model structure are doped with different types of impurities. The influence of GaAs as a substrate on the device sensitivity is also studied. Amorphous indium gallium zinc oxide (a-IGZO) material is used as a semiconductor layer to obtain a new type of ISFET with a higher detection sensitivity to the pH value. Furthermore, the addition of SiC material to the new ISFET further improves the device sensitivity. The influence of different oxide layers on the model when GaAs is used as a substrate is also studied. The results show that the new ISFET can not only break through the Nernst limit of the device sensitivity (59 mV pH−1), but also increase the sensitivity by nearly 12 times.