Temperature Dependent Charge Transport Characteristics of Ferroelectric Organic Field Effect Transistors
Date of Completion
Honors College Thesis
Honors College, College of Arts and Science Honors
Randall L. Headrick
Fe-OFET, solution processing, ferroelectricity, temperature dependence, OFET, transistor
In recent decades, organic semiconductor materials have emerged as an attractive alternative to inorganic compounds for electronics applications. One application where organic semiconductor materials show particular potential is in the fabrication of transistors, such as organic field-effect transistors. These transistors modulate and switch electrical signals by utilizing a transverse electric field to influence charge transport across the transistor channel. In this project, a top-gate bottom-contact organic field-effect transistor architecture was modified to enable the addition of a ferroelectric polymer as the gate dielectric. These transistors, known as ferroelectric organic field-effect transistors, exhibit a characteristic hysteresis in their transfer properties as a result of the dipolar polarization states present in the ferroelectric polymer, making them excellent candidates for non-volatile memory applications. In this project, functional transistors were fabricated based on the developed experimental methodologies and characterized both in air at room temperature and under vacuum at varying temperatures. These transistors exhibited strong ferroelectric properties, with differences in source-drain current as high as four orders of magnitude between polarized and unpolarized states of the ferroelectric dielectric layer at zero gate bias. Transistor performance was also evaluated through the calculation of linear charge carrier mobility. For the samples measured at room temperature, the highest linear mobility was estimated to be 0.18 cm2/V*s. Measurements taken under vacuum at variable temperatures followed expected trends. The relatively low performance observed in these Fe-OFETs is indicative of imperfections in the fabrication procedure, which still has a significant amount of room for refinement. Temperature dependence data collected from one transistor serves as a baseline for further Fe-OFET temperature dependence experiments . Overall, this project established a foundation on which further studies of ferroelectric transistors at UVM can build.
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Benson, Jared C., "Temperature Dependent Charge Transport Characteristics of Ferroelectric Organic Field Effect Transistors" (2020). UVM Honors College Senior Theses. 335.