Surface termination and Schottky-barrier formation of In₄Se₃(001)

Abstract

The surface termination of In4Se3(001) and the interface of this layered trichalcogenide, with Au, was examined using x-ray photoemission spectroscopy. Low energy electron diffraction indicates that the surface is highly crystalline, but suggests an absence of C2v mirror plane symmetry. The surface termination of the In4Se3(001) is found, by angle-resolved x-ray photoemission spectroscopy, to be In, which is consistent with the observed Schottky barrier formation found with this n-type semiconductor. Transistor measurements confirm earlier results from photoemission, suggesting that In4Se3(001) is an n-type semiconductor, so that Schottky barrier formation with a large work function metal, such as Au, is expected. The measured low carrier mobilities could be the result of the contacts and would be consistent with Schottky barrier formation.

Anisotropic Properties of Quasi‐1D In4Se3: Mechanical Exfoliation, Electronic Transport, and Polarization‐Dependent Photoresponse

“…The layered crystal structure of In 4 Se 3 allows one to obtain cleaved surfaces. [24][25][26][27]38,39] The resulting surfaces are highly ordered, as was previously shown by the low energy electron diffraction. [25,39] The cleaved crystals were examined using X-ray photoelectron spectroscopy (XPS).…”

“…[24][25][26][27]38,39] The resulting surfaces are highly ordered, as was previously shown by the low energy electron diffraction. [25,39] The cleaved crystals were examined using X-ray photoelectron spectroscopy (XPS). [38,39] Closer examinations of the In 3d 5/2 and In 3d 3/2 core-level photoemission spectra suggest the existence of two indium environments, as indicated by the binding energy shift of the fitted In 3d peaks shown in Figure 1d.…”

“…[25,39] The cleaved crystals were examined using X-ray photoelectron spectroscopy (XPS). [38,39] Closer examinations of the In 3d 5/2 and In 3d 3/2 core-level photoemission spectra suggest the existence of two indium environments, as indicated by the binding energy shift of the fitted In 3d peaks shown in Figure 1d. The In 3d 5/2 and In 3d 3/2 core-level photoemission spectra can each be deconvoluted with two components, which are associated with surface and bulk core-level indium.…”

“…There are a number of studies of the band structure for In 4 Se 3 , [24][25][26][27]39] but none where there was an effort to assign symmetry to the bands, an essential first step to identifying any light polarization effects on a photocurrent. To gain insight into the light polarization dependence of the photoconductivity, we used DFT to calculate the orbital-resolved band structures of the ac surface of In 4 Se 3 , which was cleaved according to the Type II scenario (Figure 2a).…”

“…The In 3d 5/2 and In 3d 3/2 core‐level photoemission spectra can each be deconvoluted with two components, which are associated with surface and bulk core‐level indium. [ 39 ] The In 3d 5/2 core‐level component located at 443.9 eV is associated with the bulk of In 4 Se 3 , and has a spin–orbit splitting of 7.6 eV between the In 3d 5/2 and In 3d 3/2 components. The surface In 3d 5/2 and In 3d 3/2 core‐level components are located at 444.7 and 452.1 eV, respectively, with a spin–orbit splitting of 7.4 eV.…”