Scalability Analysis and Performance Investigation of Ion-Sensitive Gated Bipolar Transistor (ISBiT) for pH Sensing Application

The forward biassing source-body diode of the ion-sensitive field effect transistor (ISFET) is used in this research to show the design and scalability analysis of the ion-sensitive gated bipolar transistor (ISBiT). The ISBiT pH sensor's construction is comparable to that of a MOSFET, with an ionsensing membrane (ISM) integrated into the gate area. This membrane interacts with hydrogen ions in the electrolyte, causing a change in the transistor's electrical properties. Tantalum pentoxide (Ta<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O5) serves as the material employed for the ion-sensing membrane (ISM). The electrolyte region has been analytically modeled by selecting the suitable parameters of intrinsic semiconductor material, where the charges of electrons and holes act as the mobile ions present in the aqueous solution. The pH sensing behaviour of ISBiT has been analyzed in the pH range from 1 to 14 and compared with conventional ISFET. The effect of reducing channel length and gate-insulator thickness on current sensitivity of ISBiT has been presented in comparison to ISFET of similar geometry. Further, the effect of tuning the body bias (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BS</inf>) on current and voltage sensitivity are also presented.