Abstract
We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.
Highlights
The presence of a band gap, absent in graphene[11], is crucial for achieving a high ON/OFF ratio in nanodevices[9]
A suitable candidate for nanoelectronics is represented by InSe, which is a layered semiconductor made of stacked layers of Se-In-In-Se atoms with van der Waals bonding between quadruple layers[18, 19]
We have studied the electronic properties of indium selenide by means of a combination of spectroscopic tools and density functional theory (DFT)
Summary
The presence of a band gap, absent in graphene[11], is crucial for achieving a high ON/OFF ratio in nanodevices[9]. A direct band gap allows the use of materials in optoelectronics[12]. Four requisites are crucial for a suitable use of 2D materials in nanotechnology: (i) high mobility of charge carriers; (ii) the possibility to achieve highly crystalline samples via mechanical/liquid exfoliation; (iii) ambient stability; (iv) high flexibility together with a sufficiently high fracture toughness. Field-effect transistors with an active channel of InSe are characterized by an electron mobility near 103 cm2/(V s)[20] and, excellent flexibility[22, 23] and ambient stability[24], in spite of the presence of a p-type doping arising from water decomposition at Se vacancies[24]. The β (space group symmetry D64h) and ɛ (space group symmetry D31h) polytypes are characterized by a hexagonal lattice consisting of eight atoms in the unit cell and extending over two layers[29], whereas rhombohedral γ-polytype (space group symmetry C35v) contains two cations and two anions distributed on four adjacent layers[27, 30]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
