Phonon-Mediated Thermal Conductivity in Suspended Graphene Membranes: Temperature Dependence from 77 K to 500 K

This study investigates phonon-mediated thermal transport in suspended single-layer graphene membranes across a 77-500 K temperature range within the context of condensed matter physics and 2D materials science, an area of growing scientific importance given its implications for thermal management design in graphene-based nanoelectronic and photonic devices. Using optothermal Raman thermometry with laser power-dependent temperature calibration, we examine Umklapp phonon-phonon scattering and defect-boundary scattering limiting phonon mean free path in 18 suspended graphene membranes spanning three defect density categories drawn from cryogenic and elevated-temperature measurement stages under high-vacuum conditions. Results indicate that thermal conductivity decreases from 4,200 W/mK at 100 K to 1,840 W/mK at 500 K in pristine samples, with defect engineering enabling tunable conductivity across a 4.2-fold range (p < 0.001), with 4.2-fold tunable conductivity range as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to condensed matter physics and 2D materials science and carry actionable implications for the design of programs and policies targeting thermal management design in graphene-based nanoelectronic and photonic devices.