Quantifying Mn Diffusion through Transferred versus Directly Grown Graphene Barriers
Quantifying Mn Diffusion through Transferred versus Directly Grown Graphene Barriers
复制标题
DOI：
10.1021/acsami.1c10701
复制
发表时间：
2021-08-25
影响因子：
9.5
通讯作者：
Kawasaki, Jason K.
中科院分区：
文献类型：
--
作者：
Strohbeen, Patrick J.;Manzo, Sebastian;Kawasaki, Jason K.
我们量化的机制，锰（Mn）通过石墨烯在Mn/石墨烯/Ge（001）和Mn/石墨烯/GaAs（001）异质结构的石墨烯层转移与石墨烯生长直接在半导体衬底上制备的样品的扩散。这些异质结构对于自旋电子学中的应用是重要的;然而，在技术上重要的衬底（例如GaAs）上直接合成石墨烯的挑战需要层转移和退火步骤，这将缺陷引入石墨烯中。原位光电子能谱测量显示，Mn通过直接在Ge（001）衬底上生长的石墨烯的扩散比Mn扩散到没有石墨烯的样品中低1000倍（D-gr，D-direct类似于4 × 10（-18）cm（2）/s，Dno-gr类似于5 × 10（-15）cm（2）/s，在500 ℃）。与没有石墨烯相比，在Ge上转移的石墨烯将Ge扩散中的Mn抑制了10倍（D-gr，D-转移类似于4 × 10（-16）cm（2）/s）。对于转移的和直接生长的石墨烯，低活化能（E-a类似于0.1- 0.5eV）表明Mn通过石墨烯的扩散主要发生在石墨烯缺陷处。这被进一步证实为扩散率前因子D-0与石墨烯片的缺陷密度成比例。在GaAs衬底上发现了类似的扩散阻挡性能;然而，目前不可能直接在GaAs上生长石墨烯。我们的研究结果强调了直接在功能衬底上开发石墨烯生长以避免层转移和退火引起的损伤的重要性。
We quantify the mechanisms for manganese (Mn) diffusion through graphene in Mn/graphene/Ge (001) and Mn/graphene/GaAs (001) heterostructures for samples prepared by graphene layer transfer versus graphene growth directly on the semiconductor substrate. These heterostructures are important for applications in spintronics; however, challenges in synthesizing graphene directly on technologically important substrates such as GaAs necessitate layer transfer and annealing steps, which introduce defects into the graphene. In situ photoemission spectroscopy measurements reveal that Mn diffusion through graphene grown directly on a Ge (001) substrate is 1000 times lower than Mn diffusion into samples without graphene (D-gr,D-direct similar to 4 x 10(-18) cm(2)/s, Dno-gr similar to 5 x 10(-15) cm(2)/s at 500 degrees C). Transferred graphene on Ge suppresses the Mn in Ge diffusion by a factor of 10 compared to no graphene (D-gr,D-transfer similar to 4 x 10(-16) cm(2)/s). For both transferred and directly grown graphene, the low activation energy (E-a similar to 0.1-0.5 eV) suggests that Mn diffusion through graphene occurs primarily at graphene defects. This is further confirmed as the diffusivity prefactor, D-0, scales with the defect density of the graphene sheet. Similar diffusion barrier performance is found on GaAs substrates; however, it is not currently possible to grow graphene directly on GaAs. Our results highlight the importance of developing graphene growth directly on functional substrates to avoid the damage induced by layer transfer and annealing.