Paper TF+AS+SS-MoM9
Electronic Structures of the Biaxially-strained GaSb(111) Films
Monday, October 19, 2015, 11:00 am, Room 111
| Session: |
Self-Assembled Monolayers, Layer-by-Layer, etc. |
| Presenter: |
Takuya Hatayama, The University of Electro-Communications (UEC-Tokyo), Japan |
| Authors: |
T. Hatayama, The University of Electro-Communications (UEC-Tokyo), Japan
A. Akaishi, The University of Electro-Communications (UEC-Tokyo)
J. Nakamura, The University of Electro-Communications (UEC-Tokyo), Japan
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| Correspondent: |
Click to Email |
III–V compound semiconductors have been extensively researched as alternative channel materials of complementary metal-oxide-semiconductor devices because of their superior carrier mobility[1]. In particular, GaSb is one of the promising p-channel materials, because its hole transport properties are significantly improved compared to Si. Recently, Ohtake et al. Have reported that high-quality GaSb films can be epitaxially grown on the Si(111) substrate using the InAs buffer layer[2]. The lattice constant in the plane of growth for the thin GaSb epilayer inherits the lattice constant of InAs, causing an inherent strain in the GaSb film. As a result, the electronic structure of the GaSb film can be modified. In this study, we evaluate the electronic properties of the strained GaSb bulk and the (111) films, especially the band gap formation, the effective mass, and the electronic conductivity, using first-principles calculations within the density functional theory. In general, the local density approximation (LDA) is commonly applied to the exchange correlation term. However, it has been well-known that the band gap of semiconductors is significantly underestimated with LDA. In order to rectify the underestimation of the band gap and to correctly evaluate electronic dispersions at band edges, we use the hybrid functional proposed by Heyd-Scuseria-Ernzerhof (HSE06) for the exchange-correlation term[3]. The spin-orbit interaction is also included. We assume the biaxial strain parallel to the GaSb (111) plane. For the bulk with a direct band gap at ambient pressure, GaSb becomes an indirect band gap material under the compressive biaxial strain. The biaxial strain makes the twofold-degenerate heavy-hole and light-hole bands split into two bands at the Gamma point of the valence band. Interestingly, under the biaxial tensile strain, the effective mass of holes becomes anisotropic. We will also report on changes in electronic properties of the GaSb (111) ultrathin films under the biaxial strain.
[1] J. A. del Alamo, Nature 479, 317 (2011)
[2] A. Ohtake, T. Mano, N. Miyata, T. Mori, and T. Yasuda, Appl. Phys. Lett. 104, 032101 (2014)
[3] J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 118, 8207 (2003); ibid 124, 219906€ (2006)