石墨烯上远程外延Ge纳米柱

远程外延能够突破传统外延中晶格匹配、热匹配等限制,近年来得到了广泛的关注。Ⅲ-Ⅴ族和Ⅲ-氮化合物半导体已经成功在石墨烯上远程外延生长,但Ⅳ族半导体的远程外延很少被报道。本文首次借助于分子束外延技术在石墨烯上远程外延制备了半导体Ge纳米柱,研究了其生长特性及剥离转移。结果表明:远程外延生长的Ge纳米柱为111]c晶向,集中分布在石墨烯的褶皱以及衬底Cu-Ni原子台阶处;随着生长温度的提高,Ge纳米柱的高度和密度逐渐下降,但直径差别不大,约为55~65 nm;此外,自组织生长的Ge纳米棒显示无应变的生长状态;引入少量Sn形成GeSn纳米柱,能够显著提升Ge纳米柱的面密度。同时,生长的Ge纳米柱可实现剥离,有望实现异质集成,应用于先进光电子器件等领域。

Remote Epitaxy of Ge Nanorods Through Graphene

Remote epitaxy has drawn great attention as it overcomes the limitations of conventional epitaxy that need the lattice and thermal diffusion coefficient matching well. Indeed, the remote interaction through graphene can get the high-quality semiconductor materials, and it also can form the freestanding membranes by releasing from the substrates. Although the Ⅲ-Ⅴ and Ⅲ-nitride compound semiconductors have successfully remote epitaxial grown on graphene, the Ⅳ group semiconductors are rarely reported. Herein, the semiconductor germanium nanorods (NRs) on monolayer graphene (MLG) substrate were successfully remote epitaxy grown using molecular beam epitaxy in this paper. Furthermore, the process of growth, lifting off and transferring was studied. Results show that the Ge NRs oriented 111]c nucleated and grew along the wrinkles of graphene and the atomic steps of Cu-Ni substrate. With the growth temperature increasing, the density and height of Ge NRs decrease gradually. However,the diameter of Ge NRs has little change between 55 nm to 65 nm. Meanwhile, the Ge nanorods by self-assembly are strain free. The surface density of Ge nanorods is improved significantly by introducing few Sn to form GeSn nanorods. Meanwhile, we successfully lifted off the Ge NRs and then transferred to the Si substrate, providing a novel strategy for the hetero-integration. This work provides a foundation for future research into the remote epitaxy of group Ⅳ semiconductors, more importantly, the technique is closely relevant to the hetero-integration for advanced devices.