Electronic structure and optical properties of Sn and SnGe quantum dots
- 15 May 2008
- journal article
- research article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 103 (10), 103712
- https://doi.org/10.1063/1.2932169
Abstract
Self-assembled quantum dots in a Si–Ge–Sn system attract research attention as possible direct band gap materials, compatible with Si-based technology, with potential applications in optoelectronics. In this work, the electronic structure near the Γ point and interband optical matrix elements of strained Sn and SnGe quantum dots in a Si or Ge matrix are calculated using the eight-band k ⋅ p method, and the competing L -valley conduction band states were found by the effective mass method. The strain distribution in the dots was found with the continuum mechanical model. The parameters required for the k ⋅ p or effective mass calculation for Sn were extracted by fitting to the energyband structure calculated by the nonlocal empirical pseudopotential method. The calculations show that the self-assembled Sn/Si dots, sized between 4 and 12 nm, have indirect interband transition energies between 0.8 and 0.4 eV and direct interband transitions between 2.5 and 2.0 eV. In particular, the actually grown, approximately cylindrical Sn dots in Si with a diameter and height of about 5 nm are calculated to have an indirect transition (to the L valley) of about 0.7 eV, which agrees very well with experimental results. Similar good agreement with the experiment was also found for SnGe dots grown on Si. However, neither of these is predicted to be direct band gap materials, in contrast to some earlier expectations.Keywords
This publication has 38 references indexed in Scilit:
- Band structure calculations of Si–Ge–Sn alloys: achieving direct band gap materialsSemiconductor Science and Technology, 2007
- New classes of Si-based photonic materials and device architectures via designer molecular routesJournal of Materials Chemistry, 2007
- TIN-BASED GROUP IV SEMICONDUCTORS: New Platforms for Opto- and Microelectronics on SiliconAnnual Review of Materials Research, 2006
- Intraband absorption in InAs/GaAs quantum dot infrared photodetectors—effective mass versusk×pmodellingSemiconductor Science and Technology, 2006
- Embedded Nanostructures Revealed in Three DimensionsScience, 2005
- Photoluminescence studies of Sn quantum dots in Si grown by MBEOptical Materials, 2005
- Void-mediated formation of Sn quantum dots in a Si matrixApplied Physics Letters, 2003
- Ge–Sn semiconductors for band-gap and lattice engineeringApplied Physics Letters, 2002
- Direct energy gap group IV semiconductor alloys and quantum dot arrays in SnxGe1−x/Ge and SnxSi1−x/Si alloy systemsMaterials Science and Engineering B, 2001
- Interband Transitions inAlloysPhysical Review Letters, 1997