The role of defects in the performance of graphene hot-electron devices.*

Defect-mediated electron-phonon collisions (supercollisions) play an important role in the cooling dynamics of hot electrons in graphene, but their impact on the performance of optoelectonic devices is still largely unexplored. Here we study supercollisions in hot-electron bolometers based on quantum dots of epitaxial graphene grown on SiC. We find that the fabrication process substantially affects the defect density and that a higher defect density greatly enhances the device performance, yielding faster response time and lower thermal conductance in a wide range of power and temperature.