Non-Planckian infrared emission from GaAs devices with electrons and lattice out-of-thermal-equilibrium

With the downscaled device size, electrons in semiconductor electronics are often electrically driven out-of-thermal-equilibrium with hosting lattices for their functionalities. The thereby electrothermal Joule heating to the lattices can be visualized directly by the noncontact infrared radiation thermometry with the hypothetic Planck distribution at a single characteristic temperature. We report here that the infrared emission spectrum from electrically biased GaAs devices deviates obviously from Planck distribution, due to the additional contribution from non-equilibrium hot electrons whose effective temperature reaches much higher than that of the lattice (T-e >T-l). The evanescent infrared emission from these hot electrons is out-coupled by a near-field metamaterial grating and is hence made significant to the total far-field emission spectrum. Resonant emission peak has also been observed when the electron hotspots are managed to overlap spatially with the optical hotspots at the grating resonance. Our work opens a new direction to study nonequilibrium dynamics with (non-Planckian) infrared emission spectroscopy and provides important implications into the microscopic energy dissipation and heat management in nanoelectronics. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Researchers have observed that the infrared emission spectrum from electrically biased GaAs devices deviates significantly from the Planck distribution due to the additional contribution of non-equilibrium hot electrons. The hot electrons emit evanescent infrared radiation, which is out-coupled by a near-field metamaterial grating, impacting the total far-field emission spectrum. Additionally, resonance emission peaks were observed when the electron hotspots spatially overlapped with the optical hotspots at the grating resonance.