Interdigitated Extended Gate Field Effect Transistor for pH Sensor Based on Porous Silicon Layer

Study introduces a pH sensor utilizing an interdigitated extended gate field-effect transistor (IEGFET) structure, incorporating a porous silicon (PS) layer. The PS layer was created via electrochemical etching on p-Type <100> silicon wafers, apply current density of 10 mA/cm2 in a 48% HF solution for a duration of 10 minutes. Surface characteristics of the resulting PS layer were examined through scanning electron microscopy (SEM). The sensor integrates this PS layer with a standard N-MOSFET, forming the IEGFET configuration. Due to increasing surface area inherent in porous structure, device demonstrated improved pH sensitivity and response linearity. The sensing capability was tested across pH levels 4, 7, and 10. Results revealed a current mode sensitivity of 0.7636 μA2/pH and a linearity of 99.89%. Voltage mode sensitivity of 53.5 mV/pH and a linearity of 99.86%. These findings validate porous silicon as an excellent for efficient and reliable pH sensing.