Scientific interests of Dr. T. Slobodskyy:

• Phone office: +49 (0) 40 42838-2040
• Phone MBE lab: +49 (0) 40 42838-6534
• Phone HRXRD lab: +49 (0) 40 42838-4033
• Phone transport lab: +49 (0) 40 42838-4030
• E-mail: tslobods (at) physnet.uni-hamburg.de

Time evolution (from left to right) of reciprocal space image of
buried InGaAs/GaAs QDs around the 220 reflection during in-situ annealing.

In-situ investigations of self-organized nanostructures

Some literature overview:

• T. Slobodskyy, A.V. Zozulya, R. Tholapi, L. Liefeith, M. Fester, M. Sprung, and W. Hansen, Versatile atomic force microscopy setup combined with micro-focused X-ray beam, Rev. Sci. Instrum. 86, 065104 (2015).
• T. Slobodskyy, P. Schroth, D. Grigoriev, A.A. Minkevich, D.Z. Hu, D.M. Schaadt, and T. Baumbach. A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines. Rev. Sci. Instrum. 83, 105112 (2012).
• P. Schroth, T. Slobodskyy, D. Grigoriev, A. Minkevich, M. Riotte, S. Lazarev, E. Fohtung, D. Z. Hu, D. M. Schaadt, T. Baumbach. Investigation of buried quantum dots using grazing incidence x-ray diffraction. Materials Science and Engineering: B 177, 721 (2012).
• Suzuki, H. et al. Real-time observation of anisotropic strain relaxation by three-dimensional reciprocal space mapping during InGaAs/GaAs (001) growth. Appl. Phys. Lett. 97, 041906 (2010).
• Fong, D.D., Lucas, C.A., Richard, M.-I. & Toney, M.F. X-Ray Probes for In Situ Studies of Interfaces. MRS Bulletin 35, 504-513 (2010).
• Renaud, G., Lazzari, R. & Leroy, F. Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering. Surf. Sci. Rep. 64, 255-380 (2009).
• Richard, M.-I. et al. In situ x-ray scattering study on the evolution of Ge island morphology and relaxation for low growth rate: Advanced transition to superdomes. Phys. Rev. B 80, 045313-9 (2009).
• Kaganer, V.M., Jenichen, B., Shayduk, R., Braun, W. & Riechert, H. Kinetic Optimum of Volmer-Weber Growth. Phys. Rev. Lett. 102, 016103-4 (2009).
• Sasaki, T. et al. In situ Real-Time X-ray Reciprocal Space Mapping during InGaAs/GaAs Growth for Understanding Strain Relaxation Mechanisms. Appl. Phys. Express 2, 085501 (2009).
• Chandril, S., Keenan, C., Myers, T.H. & Lederman, D. In situ thin film and multilayer structural characterization using x-ray fluorescence induced by reflection high energy electron diffraction. J. Appl. Phys. 106, 024308 (2009).

further reading

Spin transport. Semiconductor-metal interfaces.

Measurements and simulation of currents flowing
through two spin channels of a semimagnetic
resonant tunneling diode.

Some literature overview:

• L.-K. Liefeith, R. Tholapi, M. Hänze, R. Hartmann, T. Slobodskyy, and W. Hansen, "Influence of thermal annealing on the spin injection and spin detection through Fe/GaAs interfaces", App. Phys. Lett. 108, 212404 (2016).
• S. Wolski, C. Jasiukiewicz, V.K. Dugaev, J. Barnas, B. Landgraf, T. Slobodskyy, and W. Hansen, Charge and Spin Transport in a Metal-Semiconductor Heterostructure with Double Schottky Barriers, Acta Physica Polonica A 127, 472 (2015).
• B. Landgraf, T. Slobodskyy, Ch. Heyn, W. Hansen, Strain relaxation in metamorphic InAlAs buffers. Materials Science and Engineering: B 177, 762 (2012).
• T. Slobodskyy, Spin manipulation using semimagnetic heterostructures Vdm Verlag Dr. Müller (2008).
• M. Rüth, T. Slobodskyy, C. Gould, G. Schmidt, and L. W. Molenkamp, Fermi edge singularity in II-VI semiconductor resonant tunneling structures. Appl. Phys. Lett. 93, 182104 (2008).
• A. Slobodskyy, C. Gould, T. Slobodskyy, G. Schmidt, L. W. Molenkamp, and D. Sánchez. Resonant tunneling diode with spin polarized injector. Appl. Phys. Lett. 90, 122109 (2007).
• T. Borzenko, T. Slobodskyy, D. Supp, C. Gould, G. Schmidt, L.W. Molenkamp. Micro-patterned RTDs: Fabrication details and device performance. Microelectronic Engineering 84, 1566 (2007).
• D. Supp, T. Slobodskyy, A. Slobodskyy, C. Gould, G. Schmidt, and L.W. Molenkamp. All II-VI magnetic resonant tunneling diodes as voltage controlled spin filters. phys. stat. sol. (c) 4, No. 9, 3390 (2007).
• C. Gould, A. Slobodskyy, D. Supp, T. Slobodskyy, P. Grabs, P. Hawrylak, F. Qu, G. Schmidt, and L. W. Molenkamp Remanent Zero Field Spin Splitting of Self-Assembled Quantum Dots in a Paramagnetic Host. Phys. Rev. Lett. 97, 017202 (2006).
• S. Maximov, T. Slobodskyy, A. Gröger, F. Lehmann, P. Grabs, L. Hansen, C. R. Becker, C. Gould, G. Schmidt and L. W. Molenkamp. Micro-patterned (Zn,Be)Se/(Zn,Mn)Se resonant tunneling diodes. Semicond. Sci. Technol. 19 946-949 (2004).
• C. Gould, A. Slobodskyy, T. Slobodskyy, P. Grabs, C. R. Becker, G. Schmidt, and L. W. Molenkamp. Magnetic resonant tunnelling diodes as voltage-controlled spin selectors. phys. stat. sol. (b) 241, No. 3, 700–703 (2004).
• A. Slobodskyy, C. Gould, T. Slobodskyy, C. R. Becker, G. Schmidt, and L. W. Molenkamp.Voltage-Controlled Spin Selection in a Magnetic Resonant Tunneling Diode. Phys. Rev. Lett. 90, 246601 (2003).
• Autès, G., Mathon, J. & Umerski, A. Theory of ultrahigh magnetoresistance achieved by k-space filtering without a tunnel barrier. Phys. Rev. B 83, 052403 (2011).
• Ashraf, T. et al. Stress and interdiffusion during molecular beam epitaxy of Fe on As-rich GaAs(001). J. Phys.: Condens. Matter 23, 042001 (2011).
• Endres, B. et al. Bias dependence of spin injection into GaAs from Fe, FeCo, and (Ga,Mn)As contacts. J. Appl. Phys. 109, 07C505 (2011).
• Wada, E. et al. Inversion of Spin Photocurrent due to Resonant Transmission. Phys. Rev. Lett. 105, 156601 (2010).
• Salis, G., Fuhrer, A., Schlittler, R.R., Gross, L. & Alvarado, S.F. Temperature dependence of the nonlocal voltage in an Fe/GaAs electrical spin-injection device. Phys. Rev. B 81, 205323 (2010).

further reading

Magnetic field evolution of PL signal intensity
from a nonmagnetic quantum well coupled to
a semimagnetic barrier.

Optical and Magneto- transport investigations

Some literature overview:

• Zayachuk D. M., Slobodskyy T., Astakhov G. V., Gould C., Schmidt G., Ossau W., Molenkamp L. W., Magnetic-field-induced exchange effects between Mn ions and free carriers in ZnSe quantum wells through the intermediate nonmagnetic barrier studied by photoluminescence. Phys. Rev. B 83, 085308 (2011).
• Zayachuk D. M., Slobodskyy T., Astakhov G. V., Gould C., Schmidt G., Ossau W., Molenkamp L. W., Interaction between Mn ions and free carriers in quantum wells with asymmetrical semimagnetic barriers. EPL 91, 5 (2010).
• Sterligov, V.A., Men, Y. & Lytvyn, P.M. Giant enhancement of elastic surface plasmon-polariton scattering. Opt. Express 18, 43-48 (2010).
• McGilp, J.F. Probing surface and interface structure using optics. J. Phys.: Condens. Matter 22, 084018 (2010).
• Yamaguchi, A. et al. An Operation Circuit of a Micro-SQUID Magnetometer below 1 K. J Low Temp Phys 162, 748-753 (2010).
• Mizoo, M., Kawamura, Y., Nishioka, T., Kato, H. & Matsumura, M. Performance of magnetometer using a commercial Hall sensor. J. Phys.: Conf. Ser. 200, 112007 (2010).
• Ruth, M., Slobodskyy, T., Gould, C., Schmidt, G. & Molenkamp, L.W. Fermi edge singularity in II--VI semiconductor resonant tunneling structures. Appl. Phys. Lett. 93, 182104-3 (2008).
• Worschech, L. et al. Optical polarization of semimagnetic CdSe quantum dots with low manganese content. sst 23, 114018 (2008).
• Slobodskyy, A. et al. Resonant tunneling diode with spin polarized injector. Appl. Phys. Lett. 90, 122109-3 (2007).
• Gould, C. et al. Remanent Zero Field Spin Splitting of Self-Assembled Quantum Dots in a Paramagnetic Host. Phys. Rev. Lett. 97, 017202-4 (2006).
• Kneip, M.K. et al. Electric field control of magnetization dynamics in ZnMnSe/ZnBeSe diluted-magnetic-semiconductor heterostructures. Appl. Phys. Lett. 88, 212105-3 (2006).
• Astakhov, G.V. et al. Circular-to-Linear and Linear-to-Circular Conversion of Optical Polarization by Semiconductor Quantum Dots. Phys. Rev. Lett. 96, 027402-4 (2006).
• Kiessling, T. et al. Optical anisotropy of CdSe/ZnSe quantum dots. pss c 3, 912-915 (2006).
• Slobodskyy, A. et al. Voltage-Controlled Spin Selection in a Magnetic Resonant Tunneling Diode. Phys. Rev. Lett. 90, 246601-4 (2003).

further reading

Growth and properties of self organized and stacked nanostructures

Combined GID image demonstrating influence of
Al cover on strain and morphology of
self organized InAs quantum dots.
(left-no Al, right-1.3ML Al)

Some literature overview:

• D. Grigoriev, S. Lazarev, P. Schroth, A. A. Minkevich, M. Köhl, T. Slobodskyy, M. Helfrich, D. M. Schaadt, T. Aschenbrenner, D. Hommel and T. Baumbach, "Asymmetric skew X-ray diffraction at fixed incidence angle: application to semiconductor nano-objects", Journal of Applied Crystallography 49, 961 (2016).
• J. Kerbst, Ch. Heyn, T. Slobodskyy, and W. Hansen, "Density Limits of High Temperature- and Multiple Local Droplet Etching on AlAs", Journal of Crystal Growth 389, 18 (2014).
• P. Schroth, T. Slobodskyy, D. Grigoriev, A. Minkevich, M. Riotte, S. Lazarev, E. Fohtung, D. Z. Hu, D. M. Schaadt, T. Baumbach. Investigation of buried quantum dots using grazing incidence x-ray diffraction. Materials Science and Engineering: B 177, 721 (2012).
• Zhou, G.Y. et al. The transition from two-stage to three-stage evolution of wetting layer of InAs/GaAs quantum dots caused by postgrowth annealing. Appl. Phys. Lett. 98, 071914 (2011).
• Abramkin, D.S., Zhuravlev, K.S., Shamirzaev, T.S., Nenashev, A.V. & Kalagin, A.K. Trapping of charge carriers into InAs/AlAs quantum dots at liquid-helium temperature. Semiconductors 45, 179-187 (2011).
• Shamirzaev, T.S. et al. Carrier dynamics in InAs/AlAs quantum dots: lack in carrier transfer from wetting layer to quantum dots. Nanotechnology 21, 155703 (2010).
• Ramsey, J.J., Pan, E., Chung, P.W. & Wang, Z.M. Superlattice Growth via MBE and Green’s Function Techniques. Nanoscale Res Lett 5, 1272-1278 (2010).
• Sugaya, T. et al. Highly stacked and well-aligned In[sub 0.4]Ga[sub 0.6]As quantum dot solar cells with In[sub 0.2]Ga[sub 0.8]As cap layer. Appl. Phys. Lett. 97, 183104 (2010).
• Bailey, C.G., Hubbard, S.M., Forbes, D.V. & Raffaelle, R.P. Evaluation of strain balancing layer thickness for InAs/GaAs quantum dot arrays using high resolution x-ray diffraction and photoluminescence. Appl. Phys. Lett. 95, 203110-3 (2009).
• Hanke, M. et al. Peculiar three-dimensional ordering in (In,Ga)As/GaAs(311)B quantum dot superlattices. Appl. Phys. Lett. 94, 203105-3 (2009).
• Fu, K. & Fu, Y. Strain-induced Stranski--Krastanov three-dimensional growth mode of GaSb quantum dot on GaAs substrate. Appl. Phys. Lett. 94, 181913-3 (2009).
• Mazur, Y.I. et al. Mechanisms of interdot coupling in (In,Ga)As/GaAs quantum dot arrays. Appl. Phys. Lett. 94, 123112-3 (2009).
• Wang, Z.M. et al. Lateral alignment of InGaAs quantum dots as function of spacer thickness. Appl. Phys. Lett. 94, 083107-3 (2009).
• J, S., Halder, N., Chakrabarti, S. & Mishima, T.D. Effect of InAlGaAs and GaAs combination barrier thickness on the stacking of InAs/GaAs quantum dot heterostructure grown by MBE. IOP Conf. Ser.: Mater. Sci. Eng. 6, 012006 (2009).
• Zolotaryov, A., Schramm, A., Heyn, C. & Hansen, W. X-ray study of temperature dependent growth of InAs/AlAs(0 0 1) quantum dots. J. Phys. D: Appl. Phys. 42, 155401 (2009).
• Shamirzaev, T.S. et al. Atomic and energy structure of InAs/AlAs quantum dots. Phys. Rev. B 78, 085323 (2008).
• Andrews, A. et al. Independent control of InAs quantum dot density and size on AlxGa1–xAs surfaces. Journal of Materials Science: Materials in Electronics 19, 714-719 (2008).

further reading

Reciprocal space images of buried InGaAs/GaAs QDs around
the 220 reflection at different incidence angles.


Evolution of X-ray reflectivity spot.

High resolution X-ray nanostructure investigations

Some literature overview:

• R. Tholapi, L. Liefeith, G. Ekindorf, K. Perumal, T. Slobodskyy, and W. Hansen, Effect of low-temperature post-growth annealing on anisotropic strain in epitaxial Fe layers deposited on GaAs(001), J. Appl. Phys. 119, 245304 (2016)
• A. Zozulya, T. Slobodskyy, Th. Bartsch, A. Wetzel, D. Sonnenberg, Ch. Heyn, M. Sprung, W. Hansen, Embedded GaAs nanopillars studied by high resolution reciprocal space mapping and SEM, Phys. stat. sol. (a), 1-6 (2014).
• P. Schroth, T. Slobodskyy, D. Grigoriev, A. Minkevich, M. Riotte, S. Lazarev, E. Fohtung, D. Z. Hu, D. M. Schaadt, T. Baumbach Investigation of buried quantum dots using grazing incidence x-ray diffraction. Materials Science and Engineering: B 177, 721 (2012).
• Slobodskyy, A. et al. In-depth analysis of the CuIn1−xGaxSe2 film for solar cells, structural and optical characterization. Appl. Phys. Lett. 97, 251911 (2010).
• Riotte, M. et al. Lateral ordering, strain, and morphology evolution of InGaAs/GaAs(001) quantum dots due to high temperature postgrowth annealing. Appl. Phys. Lett. 96, 083102-3 (2010).
• Minkevich, A.A. et al. Selective coherent x-ray diffractive imaging of displacement fields in (Ga,Mn)As/GaAs periodical wires. arxiv (2009).
• Renaud, G., Lazzari, R. & Leroy, F. Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering. Surf. Sci. Rep. 64, 255-380 (2009).
• Keplinger, M. et al. Structural Investigations of Core−shell Nanowires Using Grazing Incidence X-ray Diffraction. Nano Letters 9, 1877-1882 (2009).

further reading

Investigation of polycrystalline nanofilms

Pole figures of TiN hard coatings. Left to right:101, 201, 404 reflexes.

Some literature overview:

• T. Slobodskyy, P. Schroth, A. Minkevich, D. Grigoriev, E. Fohtung, M. Riotte, T. Baumbach, M. Powalla, U. Lemmer, A. Slobodskyy. Three-dimensional reciprocal space profile of an individual nanocrystallite inside of a thin film solar cell absorber layer. J. Phys. D: Appl. Phys. 46, 475104 (2013).
• Y.F. Ivanov, N.N. Koval, O.V. Krysina, T. Baumbach, S. Doyle, T. Slobodsky, N.A. Timchenko, R.M. Galimov, and A.N. Shmakov. Superhard nanocrystalline Ti–Cu–N coatings deposited by vacuum arc evaporation of a sintered cathode. Surface and Coatings Technology 207, 430 (2012).
• A. Slobodskyy, T. Slobodskyy, T. Ulyanenkova, S. Doyle, M. Powalla, T. Baumbach, U. Lemmer. In-depth analysis of CIGS film for solar cells, structural and optical characterization. Appl. Phys. Lett. 97, 251911 (2010)
• O.V. Krysina, N.N. Koval, Y.F. Ivanov, N.A. Timchenko, T. Baumbach, S. Doyle, and T. Slobodskyy. Nanocrystalline nitride coatings deposited by vacuum arc plasma-assisted method. Journal of Physics: Conference Series 370, 012021 (2012).
• ...

further reading