Enhanced electroluminescent cooling in GaN-based light-emitting diodes

Optimized GaN-based light-emitting diodes (LEDs) were recently demonstrated to emit photons of higher energy than provided by the injected electrons up to elevated currents beyond the peak of the power conversion efficiency. Correspondingly, the electrical efficiency is above unity, which is attributed to heat extraction from the crystal lattice. In good agreement with measurements, we investigate the origin of such electroluminescent cooling by advanced numerical simulation including all relevant heat transfer mechanisms. For the first time, our simulations reveal the magnitude and the local profile of the heat extraction from the lattice. The built-in nitride polarization field is found to enhance the cooling effect significantly.