Objective
Narrow-gap IV-VI compound semiconductors offer a range of new features compared to III-V and II-VI: high values of static dielectric constant, large spin splitting. Investigations of the two-dimensional phenomena in these materials, such as the quantum Hall effect, require well lattice matched semiinsulating substrates. However the BaF2 and KCl substrates used for this purpose so far are not well matched with the IV-VI 2-D structures both in the lattice parameter and in the thermal expansion coefficient.
In the project the semiinsulating bulk lead telluride- based alloys doped with the group III impurities and/or with the rare-earth elements are proposed to be used as a substrate material for the growth of IV-VI heterostructures. In contrast to the undoped PbTe and other narrow-gap IV-VI semiconductors, where the deviation from stoechiometry results in a high free carrier concentration, the above-mentioned materials may be obtained as a semiinsulator due to the specifics of impurity states. IV-VI two-dimensional structures grown on these substrates should be well matched both in the lattice parameter and in its temperature coefficient. It gives the tremendous advantage in comparison to BaF2 and KCl substrates as the IV-VI heterostructures will not deteriorate after repeated thermal cycling due to the consequences of thermally induced strain phenomena.
In the framework of the project the partners from the FSU countries will perform growth (Chernovtsy), primary characterization (Moscow, MSU, Institute of Rare Metals) and preparation of the substrates for epitaxy (Chernovtsy). A special attention will be paid to the theoretical calculations of the expected features of impurity states in the substrate materials (Moscow, Lebedev Physical Institute). Growth and characterization of the 2-D IV-VI structures will be done in Linz and in Zurich (by MBE), and in Leoben (by HWE). The electronic properties of the structures will be studied by galvanomagnetic measurements in high magnetic fields and at the ultralow temperatures (Linz; Moscow, MSU), by photoelectric spectroscopy (Leoben; Moscow, MSU, Institute of Rare Metals; Zurich), optical spectroscopy (Linz; Leoben; Moscow, MSU, Institute of Rare Metals; Zurich). One of the main aims is the search for the fractional quantum Hall effect that has not yet been observed in this narrow gap system where the spin splitting is nearly comparable to the Landau splitting.
The results will be presented as annual reports and as the papers in the physical journals.
Topic(s)
Call for proposal
Data not availableFunding Scheme
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4040 Linz
Austria