Selective Formation of Graphene on a Si Wafer
- PDF / 2,884,549 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 49 Downloads / 167 Views
Selective Formation of Graphene on a Si Wafer Naili Yue, Yong Zhang, Raphael Tsu Department of Electrical and Computer Engineering and The Center for Optoelectronics and Optical Communications, The University of North Carolina at Charlotte, Charlotte, NC 28223, U.S.A. ABSTRACT We report a technique that can, in principle, selectively convert SiC into graphene at any location and in any size or shape, limited only by the ability of the available lithographic techniques. This technique relies on our discovery that, at ambient condition, a laser beam can convert SiC into graphene layers at the illuminated site, and the conversion can be realized in two ways. One can pattern the SiC film, which is already grown on a Si wafer, with desirable features and then illuminate the SiC film with the laser, or simply “write” the graphene features directly onto the unpatterned SiC film with the laser. Alternatively, one can pre-pattern the Si substrate to achieve selective growth of SiC, then perform the laser conversion. We have demonstrated the feasibility of both approaches. Fullerene (C60) was used to grow a thin SiC film on a Si (111) substrate using molecular beam epitaxy (MBE) at 700-800 oC. The results are verified by various structural, chemical and optical characterization techniques. This work yields the possibility of fabricating graphene based (electronic) nanostructures or superlattices, photonic crystals, and integrated electronic and optoelectronic devices on a large Si wafer. INTRODUCTION Much of the graphene growth effort has been devoted to the goal of obtaining uniform and large area material [1-6]. The large area graphene is useful for applications such as the electrode in a large device or substrate for growing another material. For applications where graphene is used either as an active material (FET for instance) or electrode in a 2-D device array, or to form a 2D (electronic) superlattice or photonic crystal, it is critically important to form graphene at selective locations, in desirable sizes and shapes on a large substrate, without relying on mechanical cutting and post-growth transfer. It would be even more advantageous if the substrate were a Si wafer in order to integrate with the mature microelectronic technology. Most reported device fabrication processes involve a graphene transfer process, which may incur contamination or damage to the sensitive graphene layer. Further patterning may also introduce impurities and damage during the ion etching process. In this work, we have developed an on-site graphene formation method without any transfer process. Specifically, a 3C-SiC layer was directly grown on a Si substrate under ultra-high vacuum (UHV), and then at ambient condition transformed into graphene in the desired size and shape, using a programmed local laser annealing process. We have demonstrated this technique in two ways: (1) First growing SiC on a Si substrate, then directing a focused laser beam from a confocal optical system onto the SiC film to convert the local SiC layer into graphene un
Data Loading...
