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Preparation of Thin Layers of Ferromagnetic Semiconductors
Koštejn, Martin
The paper reports on the experiments of preparation Mn diluted in Silicon. These materials are potential ferromagnetic semiconductors. Thin layer have been prepared by reactive pulsed laser deposition of Mn target under small pressure of volatile precursor (silane or germane). We estimate initial temperature 1 mn above surface as 1.9 eV. The prepared layers can contain 1-40% of Mn atoms in form of amorphous mixture of Mn and Si or nano-crystallized mixture of Mn and Ge. High temperature annealing or rapid laser annealing is needed for recrystallization of Mn:Si layers.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22015011914541 - PDF
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Luminescence of quantum dot heterostructures in applied electric field
Kubištová, Jana ; Zíková, Markéta ; Kuldová, Karla ; Pangrác, Jiří ; Hospodková, Alice ; Hulicius, Eduard ; Petříček, Otto ; Oswald, Jiří
In this work, photoluminescence (PL) and electroluminescence (EL) of samples with InAs/GaAs quantum dots were measured with electric voltage or current applied on the structure. The EL structures emitting at 1300 nm were prepared by using n-type substrate. By applying the electric voltage in reverse bias on the sample, the evinced PL may be switched off - it decreases rapidly with the applied voltage and is negligible at about 10 V. Such structures which PL intensity is tunable by applied voltage have a broad spectrum of applications in optoelectronics.
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GaAsSb strain reducing layer covering InAs/GaAs quantum dots
Zíková, Markéta ; Hospodková, Alice ; Pangrác, Jiří ; Oswald, Jiří ; Kubištová, Jana ; Hulicius, Eduard ; Komninou, Ph. ; Kioseoglou, J. ; Nikitis, F.
GaAsSb is often used as a capping material for InAs quantum dots (QDs) due to its suitable conduction band alignment and suppression of In segregation from QDs during the capping process.We have found out that during the GaAsSb layer growth, Sb atoms segregate above InAs QDs, which is proved by the AFM and HRTEM measurements. For higher amount of Sb in GaAsSb, the measured photoluminescence (PL) has longer wavelength, but if it is too high, the structure may become type II with decreased PL intensity. For thick GaAsSb layer, the PL intensity decreases, because only big QDs participate to the PL.
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