抄録
The investigation of electronic properties like band structures on surfaces within three-dimensional (3D) shaped structures has attracted the attention of researchers in semiconductor field. This interest arises from the potential to utilized surface carrier transport for advancing 3D transistors in order to break the limitation of downsizing 2D planar-type device. On these geometrically 3D shaped structures, it becomes quite important the creation of atomically flat and well-ordered facet surfaces in design and the construction of functional films on these facet surfaces, for device application. In addition, on artificially designed 3D structures, it could be expected the singular states arising from 3D geometry such as edges between facet surfaces, for fundamental interesting. Despite the significance of these 3D shaped structures, there is a notable scarcity of reports pertaining to the creation of 3D sample and evaluation of electronic bands.
Recently, our group has succeeded in creating 3D-Si structures by photo-lithography technique and surface reconstruction consisting of atomically ordered Si{111}7×7 facet surfaces with sharp facet lines [1-4]. By using laboratory (He source) based angle-resolved photoelectron spectroscopy (ARPES), we have initially reported a successful creation of Si{111}7×7 clean facet surfaces showing surface and bulk electronic bands [4]. In this work, we demonstrate the construction of an epitaxial grown film on Si{111} facet surfaces and film band structures, which promise electronic devices using 3D shaped high-crystalline films in future. In addition, we display valence band and core level spectra arising from the singular region as the facet edges.
In this experiment, we have constructed 3D-Si facet-lined structures on Si(001) substrates with (111) and (-1-11) facet surfaces (Fig. 1(a)) showing 7×7 reconstruction in low-energy electron diffraction (LEED) (Fig. 1(b)), and created well-ordered √3×√3-Ag as a prototype of a functional thin-film. In UVSOR BL5U, we performed the surface preparation and ARPES measurements. Indeed, after the flashing and degassing in ultra-high vacuum, we obtained clear spots Si{111}7×7 and √3×√3-Ag reconstruction and successfully obtained the surface and bulk band structure, in both facet surfaces. In order to survey specific states arising from the singular 3D regions such as edges, we measured Si 2p core levels depending on the optical geometry to discuss chemical components at 6 K (Fig. 1(c)). We will report the analyzed details with the band dispersion results.
References
[1] A. N. Hattori, K. Hattori, et al., Appl. Phys. Express 9, 085501 (2016).
[2] A. N. Hattori, K. Hattori, et al., Surf. Sci. 644, 86 (2016).
[3] S. Takemoto, K. Hattori, et al., Jpn. J. Appl. Phys. 57, 090303 (2018).
[4] K. Hattori, A. N. Hattori, et al., e-J. Surf. Sci. Nanotechnol. 30, 214 (2022).
