High-mobility graphene field-effect transistors for biosensing applications.

Doctoral thesis, 2025

Graphene, a single layer of sp2-hybridized carbon atoms arranged in a hexagonal lattice, possesses remarkable electronic, mechanical, and thermal properties, stemming from its linear band structure and Dirac-like charge carriers. These attributes make it a strong candidate for advanced technologies such as high-speed electronics, flexible devices, and biosensors. However, its broader adoption is limited by two key challenges: (i) scalable transfer of high-quality graphene without degrading its intrinsic properties, and (ii) development of stable, sensitive, and reliable biosensing platforms. Existing transfer methods for chemical vapor deposition (CVD) graphene often introduce defects and contamination, while conventional direct current (DC) biosensing techniques suffer from signal drift, hysteresis, and poor signal-to-noise ratios.

This thesis addresses these challenges through two primary research directions. The first focuses on developing a scalable, mechanically non-destructive method for transferring CVD graphene onto target substrates. This method is designed to preserve the material’s intrinsic properties by minimizing the introduction of defects, contamination, and strain-induced deformations that typically degrade charge transport. Second, the thesis explores an alternating current (AC) biasing scheme as an alternative to conventional DC measurements in graphene field-effect transistor (GFET) biosensors. The AC-based technique demonstrates improved measurement stability, enhanced sensitivity, and better resilience against environmental fluctuations, offering a more reliable platform for real-time biosensing. Additionally, this approach provides new insights into the dynamic behavior of the graphene electrolyte interface, a key element in understanding biosensor performance.

Together, these advances aim to overcome longstanding barriers in graphene device fabrication and sensing, contributing to the realization of scalable, high-performance graphene technologies for future healthcare and electronic systems.