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- Kaniewska, M., et al.
(författare)
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Hole emission mechanism in Ge/Si quantum dots
- 2011
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Ingår i: Physica Status Solidi (C) Current Topics in Solid State Physics. - : Wiley. - 1610-1642 .- 1862-6351. ; 8:2, s. 411 -413
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms determining emission of holes in self-assembled Ge quantum dots (QDs) embedded in the p-type Si matrix have been investigated. Specimens were prepared by molecular beam epitaxy (MBE). Electrical methods such as deep level transient spectroscopy (DLTS) and capacitance versus voltage (C-V) measurements were used for the study. The emission mechanisms were identified by measuring a QD-related signal as a function of the repetition frequency of the filling pulses with the reverse voltage and the pulse voltage as a parameter. An observed shift of the signal position or its absence versus the voltage parameters was interpreted in terms of thermal, tunnelling and mixed processes and attributed to the presence of a Coulomb barrier formed as a result of the charging effect. Thermal emission properties of the QDs were characterized under such measurement conditions that tunnelling contributions to the DLTS spectra could be neglected.
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| 2. |
- Kaniewska, M., et al.
(författare)
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Spatial variarion of hole eigen energies in Ge/Si quantum wells
- 2011
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735410022 ; 1399, s. 293-294
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Konferensbidrag (refereegranskat)abstract
- Ge quantum well (QW) structures were prepared through Si-capping of 3.3 ML of Ge by MBE on p +-(001) Si substrates at a growth temperature of 550°C. The spatial variation of hole eigen energies in the QW were revealed by DLTS. Depending on the position on the wafer surface, the hole emission may be imposed by a lateral quantum confinement effect. Results of a study by HRTEM methods demonstrate pronounced fluctuations of the QW thickness and variations of the strain field in the QW.
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| 9. |
- Kaczmarczyk, M, et al.
(författare)
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Comprehensive study of InAs/GaAs quantum dots by means of complementary methods
- 2009
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Ingår i: Materials Science & Engineering B: Solid-State Materials for Advanced Technology. - : Elsevier BV. - 0921-5107. ; 165:1-2, s. 98-102
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Konferensbidrag (refereegranskat)abstract
- Structural, optical, and electronic properties of self-organized InAs/GaAs quantum dots (QDs) were studied by means of atomic force microscopy (AFM), photoluminescence measurements (PL), and deep level transient spectroscopy (DLTS). We found that a well defined group of QDs with low size dispersion as revealed by AFM maintains its properties in PL spectra even if the QDs are covered by GaAs. Two well separated emission lines attributed to the QD-related ground- and excited-state transitions. respectively are found in the PL spectra. Contrary to the optical picture of a characteristic simplicity, DLTS spectra are found with higher complexity. This is due to combined thermal/tunneling processes and multi-particle emission. Despite the relatively good understanding of optical and electrical properties of QDs in PL and DLTS, respectively, there are still discrepancies between electrical and optical data for the energy of the QD ground states, which need more investigations to be explained.
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