Modulation of the dielectric property of Ga2O3/TiO2 nanolaminates and their improvement on the electroluminescence from devices based on Er-doped Al2O3 nanofilms

Abstract

Metal-oxide-semiconductor light-emitting devices (MOSLEDs) based on the erbium doped Al2O3 nanofilms still suffer from insufficient and unstable electrical injection, and the dielectric protection layers play an important role in their performance. Here, Ga2O3/TiO2 (GTO) nanolaminate films are fabricated by atomic layer deposition, the dielectric constant and leakage current of which are gradually regulated by alternating the component ratios. The tolerance to electric field and electron injection for the Al2O3:Er MOSLEDs is significantly improved, leading to the enhanced electroluminescence performance. The optimal GTO nanolaminate with thickness ratio of 4:6 could withstand the maximum breakdown electric field reaching 4.17 MV cm−1 while maintaining a high electric field of 8.4 ± 0.1 MV cm−1 within the luminescent Al2O3:Er layer (under injection of 0.3 A cm−2), resulting in the optical power density up to 11.37 mW cm−2. Much higher excitation efficiencies are also achieved with external quantum efficiency of 19.35%, and the operation time of the prototype Al2O3:Er MOSLEDs is significantly enhanced by more than two orders of magnitude from 48 s (I= 0.2 μA) to 7308 s (I = 1 μA). The design principle of the dielectric nanolaminates has been deduced, considering the dielectric and conductive contribution of different oxides, which supplies a promising route to further explore the application of optoelectronic devices based on oxides.