title: Electronic structure of (In,Mn)As quantum dots buried in GaAs investigated by soft-x-ray ARPES.
abstract: Electronic structure of a molecular beam epitaxy-grown system of (In,Mn)As quantum dots (QDs) buried in GaAs is explored with soft-x-ray angle-resolved photoelectron spectroscopy (ARPES) using photon energies around 1 keV. This technique, ideally suited for buried systems, extends the momentum-resolving capabilities of conventional ARPES with enhanced probing depth as well as elemental and chemical state specificity achieved with resonant photoexcitation. The experimental results resolve the dispersive energy bands of the GaAs substrate buried in ∼2 nm below the surface, and the impurity states (ISs) derived from the substitutional Mn atoms in the (In,Mn)As QDs and oxidized Mn atoms distributed near the surface. An energy shift of the Mn ISs in the QDs compared to (In,Mn)As DMS is attributed to the band offset and proximity effect at the interface with the surrounding GaAs. The absence of any ISs in the vicinity of the VBM relates the electron transport in (In,Mn)As QDs to the prototype (In,Mn)As diluted magnetic semiconductor. The SX-ARPES results are supported by measurements of the shallow core levels under variation of probing depth through photon energy. X-ray absorption measurements identify significant diffusion of interstitial Mn atoms out of the QDs towards the surface, and the role of magnetic circular dichroism is to block the ferromagnetic response of the (In,Mn)As QDs. Possible routes are drawn to tune the growth procedure aiming at practical applications of the (In,Mn)As based systems.
authors.affiliation: St.Petersburg Academic University RAS, 8-3 Khlopina st., 194021 St.Petersburg, Russia. Ioffe Physical Technical Institute RAS, 26 Politekhnicheskaya st., 194021 St.Petersburg, Russia. Institute for Analytical Instrumentation RAS, 31-33 Ivana Chernykh st., 190103 St.Petersburg, Russia. St.Petersburg State University, 7-9 Universitetskaya nab., 199034 St.Petersburg, Russia.
authors.forename: A D
authors.initials: AD
authors.lastname: Bouravleuv
authors.forename: L L
authors.initials: LL
authors.lastname: Lev
authors.forename: C
authors.initials: C
authors.lastname: Piamonteze
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Schmitt
authors.forename: A I
authors.initials: AI
authors.lastname: Khrebtov
authors.forename: Yu B
authors.initials: YB
authors.lastname: Samsonenko
authors.forename: J
authors.initials: J
authors.lastname: Kanski
authors.forename: G E
authors.initials: GE
authors.lastname: Cirlin
authors.forename: V N
authors.initials: VN
authors.lastname: Strocov