Band offsets and photocurrent spectroscopy of Si/Ge heterostructures with quantum dots.
Nanotechnology
; 19(14): 145703, 2008 Apr 09.
Article
em En
| MEDLINE
| ID: mdl-21817769
ABSTRACT
Raman and lateral photoconductivity spectra of self-assembled SiGe nanoislands were studied with a height of â¼2 nm and a base of â¼20 nm formed at a temperature of 500 °C. It was estimated that the value of elastic deformation (ε(xx)) was -0.022 (ε(zz) = 0.017), while the germanium content in the islands (x) was 0.66. The obtained values of x and ε were used to calculate band offsets at the interfaces and the energy of interband transitions of structures under study. It was shown that the minimal energy of photocurrent observation is 0.52 eV, which is below the bandgap of the QDs under study. The first photocurrent component which began to contribute at 0.52 eV and had a peak at 0.68 eV is explained by optical transitions of electrons from the QD HH localized states of the valence band to the conduction band Δ(2) valley of the surrounding silicon matrix in which tensile strains are present. The second component with limiting energy of 0.73 eV can be caused by interband electron transitions from the HH valence band of the QDs to the Δ(4) valley of the QD conduction band.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Nanotechnology
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Ucrânia