Gateless patterning of epitaxial graphene by local intercalation

Abstract

We present a technique to pattern the charge density of a large-area epitaxial graphene sheet locally without using metallic gates. Instead, local intercalation of the graphene-substrate interface can selectively be established in the vicinity of graphene edges or predefined voids. It provides changes of the work function of several hundred meV, corresponding to a conversion from n-type to p-type charge carriers. This assignment is supported by photoelectron spectroscopy, scanning tunneling microscopy, scanning electron microscopy and Hall effect measurements. The technique introduces materials contrast to a graphene sheet in a variety of geometries and thus allows for novel experiments and novel functionalities.

WSe 2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates

“…As described in the preceding section, a subsequent hydrogenation process was applied to intercalate hydrogen at the SiC-graphene interface and convert the initial monolayer (1L) graphene plus carbon buffer to QF2L [20]. We performed this treatment in a way such that only partial hydrogenation occurred, that is, the graphene substrate consisted of QF2L areas coexisting with 1L areas [26]. On such patterned graphene, WSe 2 forms a continuous layer by overgrowing steps between adjacent QF2L and 1L areas.…”

Terahertz response of patterned epitaxial graphene

“…We use commercially available semi-insulating hexagonal SiC(0001) as a substrate for the subsequent growth of epitaxial graphene [2]. For periodic patterning we chose a minimum invasive technique that yields n-type and ptype epitaxial graphene side-by-side within a continuous graphene sheet by local intercalation which has been detailed in our previous publication [10]. For short, we exploit the inpenetrability of a closed MLG sheet for hydrogen atoms at intermediate temperatures, i.e.…”

“…It is certainly a nontrivial question whether this subtle modulation is capable of coupling the electrons in this two-dimensional graphene sheet to electromagnetic radiation. Using a scheme that has been developed in [10], we patterned large-area graphene into p-and n-type stripes to define plasmonic gratings, with a periodicity D = 5 μm and QFBLG-width d = 2.7 μm for sample PN1. In order to define a grating that comprises isolated MLG stripes, the as-grown material in between is removed by oxygen plasma etching.…”

“…Lithographic patterning allows for the formation of plasmonic gratings in order to enhance the interaction with light. The concept of gateless patterning [10] allows intercalation doping patterns within a closed graphene sheet, without a perturbing influence of metallic or electrolytic gates. We focus on patterns with a periodicity that is substantially smaller than the free-space THz wavelength (up to three orders of magnitude).…”

Increasing the Rate of Magnesium Intercalation Underneath Epitaxial Graphene on 6H‐SiC(0001)

“…Of these techniques, intercalation (i.e., the insertion of atoms or molecules beneath or in-between graphene sheets) has been demonstrated as a relatively simple and versatile method for achieving control over graphene's key electrical properties-carrier type, [17][18][19]21] conductivity, [20,[27][28][29] and bandgap. [25,30] For instance, engineering the carrier type and bandgap via intercalation could enable graphene p-n junctions [31][32] and transistors. [33] Whereas increasing graphene's conductivity via intercalation could enable highly conductive and transparent electrodes for solar cells, [34] interconnects, [35] or new superconductors.…”