Ge quantum dots structural peculiarities depending on the preparation conditions.
Two-dimensional pseudomorphous Ge films have been grown to a critical thickness of 4 monolayers (ML) on Si(001). As a result of continuing deposition, pyramid-like Ge islands were grown in Stranski-Krastanov mode. The pyramid-like Ge islands deposited on Si(001) substrate using molecular beam epitaxy at 573 K reveal quantum dots (QDs) properties. The local microstructure parameters determined by EXAFS spectroscopy are linked to nanostructure morphology and adequate models are suggested and discussed. The pure Ge nanoclusters are covered by a 1-2 ML film with about 50% Si atom impurity caused by interface diffusion at 773 K. The influence of the effective thickness of the Ge film, Ge nanocluster sizes and Ge, Si deposition temperature on the QDs microstructure parameters is revealed. The first attempt to extract information about the energy structure of the free states of the quantum dot from X-ray absorption spectra (XANES spectra) was made. It was established that the maximum in the XANES spectra of a sample doped with boron is due to the appearance of free levels in the quantum dots at a depth of the order of 1.1 eV from the bottom of the Ge conduction band.
Erenburg
Simon
S
Institute of Inorganic Chemistry SB RAS, Lavrentiev Avenue 3, Novosibirsk 630090, Russia. simon@che.nsk.su
Bausk
Nikolai
N
Mazalov
Lev
L
Nikiforov
Alexandr
A
Yakimov
Andrei
A
D015502:Absorptiometry, Photon / Q000379:methods*; D001895:Boron / Q000737:chemistry; D003461:Crystallography / Q000379:methods*; D005857:Germanium / Q000737:chemistry*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*
D005857:Germanium; D001895:Boron; D012825:Silicon