Ferroelectric Polarization Enhancement of Proximity Sensing Performance in Oxide Semiconductor Field-Effect Transistors

The explosive development of Internet of Things and wearable electronics greatly promotes the exploitation of diverse sensors in which noncontact proximity sensing is of great significance to perceive diverse information from the environment and human bodies with no need for physical contact. In theory, any long-range interactions can be developed to realize proximity sensing function. In recent years, organic field-effect transistor-based proximity sensors have been realized in which a charged object can be regarded as a gate to modulate transistor's drain current. However, the low-carrier mobility and shift of threshold voltage in organic transistors limited their sensing performance. Herein, we reported a ferroelectric-polarization-enhanced oxide semiconductor transistor proximity sensor. The polarization state in the ferroelectric layer was well modulated by poling pulse with different widths. Therefore, the optimal operation point of the transistor sensor was precisely controlled by the ferroelectric-polarization-induced shift of the threshold voltage. Such a ferroelectric-modulated oxide semiconductor transistor showed obvious sensing performance to the approach of several common charged objects and presented a much larger current response than that from organic transistor sensors. As an extended application, two transistor sensors were configured to realize the velocity measurement of a charged object.