Towards n-type conductivity in hexagonal boron nitride
Shiqiang Lu, Peng Shen, Hongye Zhang, Guozhen Liu, Bin Guo, Yehang Cai, Han Chen, Feiya Xu, Tongchang Zheng, Fuchun Xu, Xiaohong Chen, Duanjun Cai, Junyong Kang
Abstract
Abstract Asymmetric transport characteristic in n - and p -type conductivity has long been a fundamental difficulty in wide bandgap semiconductors. Hexagonal boron nitride (h-BN) can achieve p -type conduction, however, the n -type conductivity still remains unavailable. Here, we demonstrate a concept of orbital split induced level engineering through sacrificial impurity coupling and the realization of efficient n -type transport in 2D h-BN monolayer. We find that the O 2 p z orbital has both symmetry and energy matching to the Ge 4 p z orbital, which promises a strong coupling. The introduction of side-by-side O to Ge donor can effectively push up the donor level by the formation of another sacrificial deep level. We discover that a Ge-O 2 trimer brings the extremely shallow donor level and very low ionization energy. By low-pressure chemical vapor deposition method, we obtain the in-situ Ge-O doping in h-BN monolayer and successfully achieve both through-plane (~100 nA) and in-plane (~20 nA) n -type conduction. We fabricate a vertically-stacked n -hBN/ p -GaN heterojunction and show distinct rectification characteristics. The sacrificial impurity coupling method provides a highly viable route to overcome the n -type limitation of h-BN and paves the way for the future 2D optoelectronic devices.