A stress sensor based on a silicon field effect transistor comprising a piezoelectric AlN gate dielectric

Abstract

Piezoelectric materials have been introduced to transistor gate stacks to improve MOSFET behaviour and develop sensor applications. In this work, we present an approach to a partly industrial field effect transistor, with a gate stack based upon low temperature AlN. Using the piezoelectric effect of the nitrogen-polar AlN, we are able to drive the transistor by inducing strain across the device. To ensure maximum sensitivity, the piezoelectric material is placed as closely to the transistor channel as possible and the transistor is operated in the most sensitive part of the sub-threshold regime. This allows the detection of different magnitudes of force applied to the device and to easily distinguish between them. The created sensor was analysed using XRD, current–voltage and specific force application measurements. Furthermore, the continuous response to periodic low frequency stimulation is investigated. Therefore, we introduce a highly scalable device with a wide range of application possibilities, ranging from varying sensor systems to energy harvesting.