1. |
- Kaniewska, M., et al.
(author)
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Hole emission mechanism in Ge/Si quantum dots
- 2011
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In: Physica Status Solidi (C) Current Topics in Solid State Physics. - : Wiley. - 1610-1642 .- 1862-6351. ; 8:2, s. 411 -413
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Journal article (peer-reviewed)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.
(author)
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Spatial variarion of hole eigen energies in Ge/Si quantum wells
- 2011
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In: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735410022 ; 1399, s. 293-294
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Conference paper (peer-reviewed)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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4. |
- Balestra, F., et al.
(author)
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NANOSIL network of excellence-silicon-based nanostructures and nanodevices for long-term nanoelectronics applications
- 2008
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In: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 11:5-6, s. 148-159
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Journal article (peer-reviewed)abstract
- NANOSIL Network of Excellence [NANOSIL NoE web site < www.nanosil-noe.eu >], funded by the European Commission in the 7th Framework Programme (ICT-FP7, no 216171), aims at European scale integration of the excellent European research laboratories and their capabilities in order to strengthen scientific and technological excellence in the field of nanoelectronic materials and devices for terascale integrated circuits (ICs), and to disseminating the results in a wide scientific and industrial community. NANOSIL is exploring and assessing the science and technological aspects of nanodevices and operational regimes relevant to the n+4 technology node and beyond. It encompasses projects on nanoscale CMOS and beyond-CMOS. Innovative concepts, technologies and device architectures are proposed-with fabrication down to the finest features, and utilising a wide spectrum of advanced deposition and processing capabilities, extensive characterization and very rigorous device modeling. This work is carried out through a network of joint processing, characterization and modeling platforms. This critical interaction strengthens European integration in nanoelectronics and will speed up technological innovation for the nanoelectronics of the next two to three decades.
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5. |
- Kaniewska, M., et al.
(author)
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Charge carrier traffic at self-assembled Ge quantum dots on Si
- 2012
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In: 6th International Silicon-Germanium Technology and Device Meeting, ISTDM 2012, Berkeley, 4-6 June 2012. - 9781457718625 ; , s. 70-71
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Conference paper (peer-reviewed)abstract
- Due to their interesting size-dependent properties, semiconductor Quantum Dots (QDs) have many potential applications in nanoelectronics and optoelectronics. Ge QDs are particularly attractive because of the compatibility of Ge with Si technology and the ability to grow dislocation-free Ge QDs through the Stranski-Krastanov growth mode. Recently given examples include mm-wave circuit operation [1] with Ge QD Schottky diodes of 1.1 THz transit frequency or room temperature single electron memory [2] function of double (Si,Ge) dots. In this paper the voltage dependent occupation of states and their filling dynamics is investigated in two terminal device structures (Schottky barrier diode, p/n junction) by capacitance voltage (C-V) and deep level transient spectroscopy (DLTS) methods. Frequency scanned DLTS (FS-DLTS) was used, where the DLTS signal at a constant temperature is measured as a function of the repetition frequency of electrical pulses, f, with the emission voltage of the pulses, VR, as a parameter. Presenting DLTS spectra as a contour plot on a (f, VR)-plane, where contour lines with negative (positive) slope reflect signals related to thermal (tunnelling) transitions makes it possible to distinguish between these emission paths.
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6. |
- Kaniewska, M, et al.
(author)
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Charge carrier traffic at self-assembled Ge quantum dots on Si
- 2013
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In: Solid-State Electronics. - : Elsevier BV. - 0038-1101. ; 83, s. 99-106
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Journal article (peer-reviewed)abstract
- Germanium quantum dots (QDs) have been characterized by deep level transient spectroscopy (DLTS) and capacitance versus voltage (C-V) technique. Two types of dots, grown by molecular beam epitaxy (MBE) at different temperatures, were investigated and assessed with respect to morphological properties. Samples with dots grown at 350 degrees C, were designed as n(++)-p-p(++) silicon junctions with the QDs positioned in the depleted p-region, while a second type of samples were Shottky diodes based on medium doped silicon with the QDs prepared at 550 degrees C and positioned in the Schottky depletion region. From the combined results of temperature scanned and frequency scanned DLTS, and by varying hole filling levels of the QD potentials, the energy distribution of states in the QD potentials were investigated. A wider distribution was found for the low-temperature QDs, probably related with a larger variation of size. By using a technique for separating tunneling and thermal hole emission, the average thermal activation energy for emitting holes to the valence band was found close to 0.40 eV for both types of QDs.
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