Accurate electronic and optical properties of hexagonal germanium for optoelectronic applications
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2019-03-11 |
| Journal | Physical Review Materials |
| Authors | Claudia Rödl, J. Furthmüller, Jens Renè Suckert, Valerio Armuzza, F. Bechstedt |
| Institutions | Friedrich Schiller University Jena |
| Citations | 69 |
Abstract
Section titled “Abstract”High-quality defect-free lonsdaleite Si and Ge can now be grown on hexagonal\nnanowire substrates. These hexagonal phases of group-IV semiconductors have\nbeen predicted to exhibit improved electronic and optical properties for\noptoelectronic applications. While lonsdaleite Si is a well-characterized\nindirect semiconductor, experimental data and reliable calculations on\nlonsdaleite Ge are scarce and not consistent regarding the nature of its gap.\nUsing ab initio density-functional theory, we calculate accurate structural,\nelectronic, and optical properties for hexagonal Ge. Given the well-known\nsensitivity of electronic-structure calculations for Ge to the underlying\napproximations, we systematically test the performance of several\nexchange-correlation functionals, including meta-GGA and hybrid functionals. We\nfirst validate our approach for cubic Ge, obtaining atomic geometries and band\nstructures in excellent agreement with available experimental data. Then, the\nsame approach is applied to predict electronic and optical properties of\nlonsdaleite Ge. We portray lonsdaleite Ge as a direct semiconductor with only\nweakly dipole-active lowest optical transitions, small band gap, huge\ncrystal-field splitting, and strongly anisotropic effective masses. The\nunexpectedly small direct gap and the oscillator strengths of the lowest\noptical transitions are explained in terms of symmetry and back-folding of\nenergy bands of the diamond structure.\n
Tech Support
Section titled “Tech Support”Original Source
Section titled “Original Source”References
Section titled “References”- 1996 - Fundamentals of Semiconductor Physics [Crossref]