Hexagonal SixGe1-xas a direct-gap semiconductor
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-07-01 |
| Authors | Christopher A. Broderick |
| Institutions | University College Cork, University of California, Santa Barbara |
Abstract
Section titled âAbstractâThe band gap of germanium (Ge) is âweaklyâ indirect, with the L6c conduction band (CB) minimum lying only â150meV below the zone-center Î7c CB edge in energy. This has stimulated significant interest in engineering the band structure of Ge, with the aim of realizing a direct-gap group-IV semiconductor compatible with established complementary metal-oxide-semiconductor fabrication and processing infrastructure. Recent advances in nanowire fabrication now allow growth of Ge in the metastable lonsdaleite (âhexagonal diamondâ) phase, reproducibly and with high crystalline quality. In its lonsdaleite allotrope Ge is a direct- and narrow-gap semiconductor, in which the zone-center T8c CB minimum originates via back-folding of the L6c CB minimum of the conventional cubic (diamond) phase. Here, we analyze the electronic structure evolution in direct-gap lonsdaleite SixGe 1-x alloys from first principles, using a combination of alloy supercell calculations and zone unfolding. We confirm the Si composition range x⤠25 % across which SixGe 1-x possesses a direct band gap, quantify the impact of alloy-induced band hybridization on the inter-band optical matrix elements, and describe qualitatively the consequences of the alloy band structure for carrier recombination.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2009 - Accurate band gaps of semiconductors and insu-lators with a semilocal exchange-correlation potential
- 2020 - Electronic structure of lonsdaleite SixGel-x alloys