Atomic-Layer-Deposited ZnO/Al₂O₃ Nanolaminates for White-Light-Emitting Diodes

A strategy of utilizing Zn interface states in wavelength-tunable electroluminescence has been investigated in a ZnO/Al2O3 nanolaminate (ZANL). The wavelength center changes from 650 to 480 nm by decreasing the nominal ZnO sublayer thickness (ZST) from 1.19 to 0.85 nm. With a ZST below the Bohr radius, the quantum confinement widens the gap between the conduction band bottom (CBB) and the Zn-interface-state-related deeplevel (DL), which suppresses nonradiative transitions and promotes a CBB/DL radiative transition. More importantly, white-light emission with a high color rendering index of 93.13 is innovatively achieved by constructing a combined ZANL with different ZSTs, which is beneficial for further lowering the cost of solid-state illumination.