Premium
Space Charge Spectroscopy of Self Assembled Ge Quantum Dots in Si
Author(s) -
Asperger Th.,
Miesner Ch.,
Brunner K.,
Abstreiter G.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200103)224:1<237::aid-pssb237>3.0.co;2-s
Subject(s) - quantum dot , coulomb blockade , spectroscopy , density of states , condensed matter physics , materials science , schottky diode , fermi level , atomic physics , space charge , diode , biasing , molecular physics , physics , optoelectronics , voltage , electron , quantum mechanics , transistor
Admittance spectroscopy was used to investigate the density of states in self assembled Ge quantum dots (QDs) of different size embedded in Si Schottky diodes. From the admittance results, activation energies of hole in the QDs have been determined as a function of the external bias which shifts the Fermi level with respect to the energy states in the QDs. The activation energy of a quantum well sample remains constant up to 6 V bias voltage. Large Ge dots (70 nm diameter) show a continuum of activation energies and a low continuous averaged density of states. In small Ge dots (20 nm diameter) a discrete energy level structure with level separations of 40 to 4 meV are observed. They are attributed to strongly quantum confined hole states with significant Coulomb blockade energies.