Unified Mechanism for Graphene FET's Electrothermal Breakdown and Its Implications on Safe Operating Limits

Unique electrothermal properties of graphene and the chemical nature of its degradation present a compelling set of conditions for the exploration of its breakdown at different time scales. In this work, we give a phenomenological description of graphene's electrical breakdown ranging from a nonequilibrium (transient) electrothermal state to far-equilibrium state while spanning a time scale from few nanoseconds to few minutes. The intricate roles of Pauli-blocked states, intraband heating, and mechanism of degradation in defining a safe operating area (SOA) have been explored. The time and field evolution of defects, resulting in defect-by-defect breakdown, have been studied using Raman spectroscopy. The unified mechanism of breakdown discussed here provides a basic understanding of reliability of graphene-based devices under high-current and/or high-field conditions as well as degradation due to its prolonged operation.