OPTICAL MONITORING OF THE DEVELOPMENT OF INAS QUANTUM DOTS ON GAAS(001) BY REFLECTANCE ANISOTROPY SPECTROSCOPY

Citation
E. Steimetz et al., OPTICAL MONITORING OF THE DEVELOPMENT OF INAS QUANTUM DOTS ON GAAS(001) BY REFLECTANCE ANISOTROPY SPECTROSCOPY, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 14(4), 1996, pp. 3058-3064
Citations number
12
Categorie Soggetti
Physics, Applied
ISSN journal
10711023
Volume
14
Issue
4
Year of publication
1996
Pages
3058 - 3064
Database
ISI
SICI code
1071-1023(1996)14:4<3058:OMOTDO>2.0.ZU;2-8
Abstract
Reflectance anisotropy spectroscopy (RAS) in combination with reflecti on high-energy electron diffraction (RHEED) was used to study in situ the initial steps of molecular beam epitaxial growth of InAs on GaAs(0 01). Due to the large lattice mismatch InAs is known to grow in Strans ki-Krastanov mode leading to the formation of quantum dots after the t ransition from two- to three-dimensional growth mode. In this article the precise determination of the growth mode transition and the subseq uent development of the islands have been of particular interest. Duri ng the growth of the two-dimensional InAs layer, the RHEED-pattern cha nged from the c(4x4) of the clean GaAs to a (1x3) surface reconstructi on. Accordingly, the RAS-spectra, taken every 0.2 ML, indicate changes of the As-dimer configuration. At 1.8 ML (spotty RHEED-pattern) a sat uration of the intensity of the dimer related RAS-signal around 2.6 eV was found. The relaxation of the InAs layer and the formation of the quantum dots was followed by time-resolved RAS at 2.6 and 4 eV. It is shown here, that the time constant of this process, the thickness of t he InAs wetting layer and the equilibrium morphology of the islands ar e strongly temperature dependent. The remaining equilibrium InAs wetti ng layer thickness at the surface was estimated to be about 1 ML (0.8 ML at 625 K and 1.2 ML at 725 K). (C) 1996 American Vacuum Society.