In the quest to produce efficient and lasting blue light-emitting diodes, one material has been largely overlooked -- zinc oxide.
Although ZnO has a room-temperature band gap of 3.37 eV and high exciton binding energy, scientists have focused more on ZnSe and GaN for blue diodes. Researchers from Japan's Tohoku University recently reported optically pumped lasing in ZnO epitaxial layers at room temperature.