High brightness blue electroluminescence of diamond/TmF3/LiF/TmF3 composite film

Although GaN-based blue light materials have been widely used in the field of optoelectronics, due to the high cost of preparation, and the emission wavelength of GaN-based devices will be easily affected by temperature and other external environment. Therefore, the development of other types of blue EL devices becomes another important option. In this paper, diamond/TmF3 composite film (DTCF) and diamond/TmF3/LiF/TmF3 composite film (DTLTCF) electroluminescent (EL) devices were fabricated on highly doped p-type silicon substrates. And experimental results show that the EL spectrum of DTCF device shows three peaks appear at 416 nm, 456 nm and 676 nm, while the EL spectrum of DTLTCF device only exhibits two strong peaks at 416 nm and 456 nm in the blue region. At the same time, the maximum luminous intensity of DTLTCF device is 2.5 times that of DTCF device, and the brightness can reach 25 cd/m2. The luminescence mechanism of DTCF and DTLTCF devices is discussed, and the mechanism of enhancing blue light emission and inhibiting red light emission by LiF layer is explained reasonably.