High sensitivity In-Ga-Zn-O nanofiber-based double gate field effect transistors for chemical sensing

Abstract

Herein, a high sensitivity In-Ga-Zn-O (IGZO) nanofiber channel double gate (DG) field-effect transistor (FET)-based chemical sensor is described. Transparent and flexible IGZO nanofiber channels were fabricated by electrospinning, and IGZO film channels were prepared for comparison via spin coating. We connected a separative extended gate (EG) with a chemical sensing membrane to the fabricated IGZO FETs to test their applicability to pH sensing applications. The effectiveness of the IGZO nanofiber channel was verified by comparing the pH sensitivity and non-ideal effects such as drift and hysteresis voltage with the IGZO film channel. The nanofiber channel showed much higher sensitivity in the dual gate ion-sensitive field-effect transistor (DG ISFET) than the film channel as it has an increased capacitive coupling effect due to an increase in the upper channel surface area and a decreased channel bottom surface area. The sensitivity of the DG ISFET with an IGZO nanofiber channel was 998 mV/pH at room temperature, surpassing the 384 mV/pH of the IGZO film channel, which itself far exceeded the Nernstian limit of 59.16 mV/pH. Furthermore, the nanofiber channel had a lower hysteresis voltage and drift rate compared to its amplified sensitivity, and exhibited a more stable performance than the film channel. Therefore, IGZO nanofiber-based DG FET chemical sensors are expected to be promising for use in transparent and wearable biosensor applications.