Saga University in Japan has reported work towards white light-emitting diodes (WLEDs) based on rare-earth (RE)-doped gallium oxide (Ga2O3) [Yafei Huang et al, Appl. Phys. Lett., v119, p062107, 2021].   The researchers adopted a vertical integration strategy with Ga2O3 layers doped with thulium (Tm), europium (Eu) and erbium (Er) grown on top of each other. The team comments that “films grown by lateral integration are deposited side-by-side, while the co-doping of multiple rare earth elements into the same host will unavoidably degrade the crystal ...