Electron Assisted Growth of Graphene atop Ir(111) supported Hexagonal Boron Nitride

Sammanfattning: Vertical heterostructures between graphene (Gr) and hexagonal boron nitride (hBN) have attracted a great deal of interest, due to their potential applications in the semiconductor industry as new and superior transistor materials. The direct growth of the heterostucture still remains challenging and in this bachelor thesis, I report a novel electron assisted growth technique, which is used to attempt to grow Gr atop hBN atop an Ir(111) single crystal surface. This technique has already proven to be successful in the opposite order of growing hBN atop Gr/Ir(111)[1]. To properly understand the growth and possible heterostructure formation, pure phases of both hBN and Gr on Ir(111) are characterized first using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). This structural characterization of the pure phases reveals a stronger binding of hBN than Gr to Ir(111) and, therefore, a favored stacking order of Gr atop hBN. In contrast to this expectation, my STM and LEED results of the electron assisted growth of Gr atop a full hBN layer show, that the temperature required for Gr formation is too high for hBN layer to sustain, and is already complicated by a low sticking coefficient of ethylene atop. After high temperature annealing, the hBN layer is determined to leave behind a (6x2) boron nanoribbon superstructure and no ordered Gr islands are observed. However, the effect of the electron beam in the growth technique is indicated to result in an uneven charging of the hBN layer on Ir(111), and this, in combination with its already highly corrugated pore-wire structure, calls for new research.