Andrei M. Yakunin

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The wave function of a hole bound to an individual Mn acceptor in GaAs is spatially mapped by scanning tunneling microscopy at room temperature and an anisotropic, crosslike shape is observed. The spatial structure is compared with that from an envelope-function, effective mass model and from a tight-binding model. This demonstrates that anisotropy arising(More)
Transition-metal dopants such as Mn determine the ferromagnetism in dilute magnetic semiconductors such as Ga(1-x)Mn(x)As. Recently, the acceptor states of Mn dopants in GaAs were found to be highly anisotropic owing to the symmetry of the host crystal. Here, we show how the shape of such a state can be modified by local strain. The Mn acceptors near InAs(More)
The local density of states of Mn-Mn pairs in GaAs is mapped with cross-sectional scanning tunneling microscopy and compared with theoretical calculations based on envelope-function and tight-binding models. These measurements and calculations show that the crosslike shape of the Mn-acceptor wave function in GaAs persists even at very short Mn-Mn spatial(More)
Measurements of the local density of states of individual acceptors in III-V semiconductors show that the symmetry of the acceptor states strongly depends on the depth of the atom below a (110) surface. Tight-binding calculations performed for a uniformly strained bulk material demonstrate that strain induced by the surface relaxation is responsible for the(More)
The spectral properties of La/B, La/B(4)C, and LaN/B, LaN/B(4)C multilayer mirrors have been investigated in the 6.5-6.9 nm wavelength range based on measured B and B(4)C optical constants. Experimentally it is verified to what extent measured and tabulated optical constants are applicable for simulations of the reflectivity of these short period multilayer(More)
We have developed a multilayer mirror for extreme UV (EUV) radiation (13.5 nm), which has near-zero reflectance for IR line radiation (10.6 μm). The EUV reflecting multilayer is based on alternating B4C and Si layers. Substantial transparency of these materials with respect to the IR radiation allowed the integration of the multilayer coating in a resonant(More)
In the first part of this article we experimentally show that contrast between the very thin layers of La and B enables close to theoretical reflectance. The reflectivity at 6.8 nm wavelength was measured from La/B multilayer mirrors with period thicknesses ranging from 3.5 to 7.2 nm at the appropriate angle for constructive interference. The difference(More)
An extreme ultraviolet multilayer mirror with an integrated spectral filter for the IR range is presented and experimentally evaluated. The system consists of an IR-transparent B4C/Si multilayer stack which is used both as EUV-reflective coating and as a phase shift layer of the resonant IR antireflective (AR) coating. The AR coating is optimized in our(More)
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