Strategy toward white LEDs based on vertically integrated rare earth doped Ga2O3 films
Yafei Huang, Katsuhiko Saito, Tooru Tanaka, Qixin Guo
Abstract
Monolithic and phosphor-free light-emitting diodes (LEDs) have been fabricated based on vertically integrated Ga2O3:Tm, Ga2O3:Eu, and Ga2O3:Er films by alternate-target pulsed laser deposition. Direct white light emission with superior CIE chromaticity coordinates of (0.3329, 0.3335) and correlated color temperature of 5479 K has been achieved from LEDs. Electroluminescence spectra demonstrate that the white emission was a consequence of the combination of dominant blue emissions at 461 and 475 nm from Tm3+ ions, green emissions at 529 and 550 nm from Er3+ ions, and red emissions at 590 and 615 nm from Eu3+ ions. The Ga2O3:(Tm+Eu+Er)-based LED exhibits current-controlled color tunability, which endows it with the capability of affording both “warm” and “cold” white light by controlling the operating current. Moreover, this strategy for LEDs shows the full color tunability by intentionally modifying the thickness ratios of Ga2O3:Tm, Ga2O3:Eu, and Ga2O3:Er monolayers. We anticipate that this study will pave the way toward full-color displays and solid-state lighting technology using rare-earth doped Ga2O3.