Study of Al/a-Si:H/SiO2/n-Si/Al based bottom gate thin film transistor using RPCVD SiO2 and PECVD a-Si:H thin films: probably needed focus for bio-sensing application

Abstract

In the present study Al/a-Si:H/SiO2/n-Si/Al based bottom gate thin film transistor (BGTFT) was fabricated using remote plasma enhanced chemical vapor deposited (RPCVD) SiO2 and PECVD a-Si:H. The Al/a-Si:H/SiO2/n-Si/Al based bottom gate thin film transistor was studied with an intension to apply it for bio-sensing application. The transfer characteristics of BGTFT were studied. The values of Gdd are 3.14 × 10−7 S, 1.38 × 10−7 S, 3.34 × 10−8 S, 4.84 × 10−9 S & 1.57 × 10−10 S for gate voltage Vg = −2, −1, 0, 1 & 2 V respectively. The Gdd values are found to decrease with the increase of gate voltage (Vg). The values of Gdg are 5.36 × 10−8 S, 5.98 × 10−9 S, 7.28 × 10−7 S, 2.40 × 10−7 & 5.00 × 10−9 respectively for Vd = −2, −1, 0, 1 & 2 V. The present current level and the conductance of BGTFT is so large that it is not possible to detect the proteins and antibody as these bio-molecules have charge of the order of nano amps. Therefore it requires a needed focus to study the ferroelectric or high k material as the active material instead of a-Si:H for BGTFT for bio-sensing application as the ferroelectric materials have low conductance and channel current. This will be our future work to use ferroelectric or high k materials as the active materials of BGTFT.