Xia Chengtao, Chen Jinxin, Zhao Tong, Fan Linlin, Yang Deren, Ma Xiangyang
State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
ACS Appl Mater Interfaces. 2022 Oct 5;14(39):44498-44505. doi: 10.1021/acsami.2c08003. Epub 2022 Sep 21.
We report on the visible and near-infrared electroluminescence (EL) from the light-emitting device (LED) based on the erbium (Er)-doped ZnO (ZnO:Er)/SiO/n-Si heterostructure, wherein an ∼10 nm thick SiO intermediate layer serves as the energy plateau for producing hot electrons, which come from n-Si via the trap-assisted tunneling mechanism. These hot electrons excite the doped Er ions by inelastic collision, enabling the Er-related EL from the aforementioned LED. More importantly, by means of codoping the appropriate content of titanium (Ti) into the ZnO:Er film, the aforementioned Er-related emissions can be significantly enhanced. The density functional theory calculations indicate that the Ti-codoping improves rather than degrades the symmetry of the crystal field around the optically active Er ions, hence not increasing the intra-4f transition probabilities of Er ions. However, it is found that Ti-codoping nearly eliminates the segregation of Er ions near the ZnO/SiO interface. Moreover, Ti-codoping is derived to result in a number of Zn vacancies, which provide the sites for incorporating Er ions in the ZnO matrix. For the above two reasons, the Ti-codoping promotes the incorporation of optically active Er ions into the ZnO matrix, thus enhancing the EL from the aforementioned LED.
我们报道了基于掺铒（Er）的氧化锌（ZnO:Er）/SiO/n-Si异质结构发光器件（LED）的可见光和近红外电致发光（EL），其中约10nm厚的SiO中间层作为产生热电子的能量平台，这些热电子通过陷阱辅助隧穿机制从n-Si产生。这些热电子通过非弹性碰撞激发掺杂的Er离子，从而使上述LED产生与Er相关的EL。更重要的是，通过向ZnO:Er薄膜中共掺杂适当含量的钛（Ti），上述与Er相关的发射可以显著增强。密度泛函理论计算表明，Ti共掺杂改善而非降低了光学活性Er离子周围晶体场的对称性，因此不会增加Er离子的4f内跃迁概率。然而，发现Ti共掺杂几乎消除了Er离子在ZnO/SiO界面附近的偏析。此外，Ti共掺杂导致产生大量的Zn空位，这些空位为在ZnO基体中掺入Er离子提供了位点。基于上述两个原因，Ti共掺杂促进了光学活性Er离子掺入ZnO基体，从而增强了上述LED的EL。
