Research topics

Publications

Projects

 

 

 

Joint Semiconductors Surface Study group


This group is formed to study the reactions at semiconductor surfaces. This is a nonofficial team of scientists from four different institutes, most of them having other scientific activities also.

Group members:

Inorganic chemistry division, Chemistry dept., M.V. Lomonosov Moscow State University:

Institute of Solid State Physics RAS, Chernogolovka:

Institute of Problems of Chemical Physics RAS, Chernogolovka:

State Institute for Rare Metals, Moscow:

Research topics:

The object of scientific interest A4B6 narrow gap semiconductors and their solid solutions (both pure and doped).

There are four main research topics:

    1. The reactivity of surfaces at semiconductor-gas interfaces, as well as structural and electronic properties of clean semiconductor surfaces studied by means of XPS, AES, AR XPS, UPS, LEED, STM, EELS, adsorption study by statical method.
    2. A4B6 semiconductors crystal growth by means of VLS and Bridgman techniques.
    3. Binary, ternary and quasiternary equilibrium phase diagrams investigation and thermodynamic modeling.
    4. Quantum chemical modeling of semiconductors surface reactions with different gases such as O2, H2S, H2O, CO2 and their mixtures are carried out within cluster model using PM3 method and the density functional theory (B3LYP).

Selected publications:

1. L.V.Yashina, V.I.Shtanov, Z.G.Yanenko. The application of VLS growth technique to bulk semiconductors. Journal of Crystal Growth, 2003, v.252, p.68-78.

Abstract

2. V.P.Zlomanov, L.V.Yashina. Phase Diagrams and Growth of Bulk Lead Chalcogenides Crystals, Chapter II in Lead Chalcogenides: Physics And Applications ed. D.Khokhlov, Gordon&Breach, 2002, p.35-121.

3. L.V.Yashina, S.P.Kobeleva, V.S.Neudachina, T.B.Shatalova, V.P.Zlomanov. XPS study of fresh and oxidized (Pb,Ge)Te crystal surface. Surface and Interface Analysis, 2002, v.34, p.498-501.

Abstract

4. L.V.Yashina, S.P.Kobeleva, T.B.Shatalova, V.P.Zlomanov, V.I.Shtanov, XPS study of fresh and oxidized GeTe and (Ge,Sn)Te surface. Solid State Ionics, 2001, v.141-142, p.513-522.

Abstract

5. L.V.Yashina, V.Leute. The Phase Diagrams of the Quasibinary Systems (Pb,Ge)Te and (Sn,Ge)Te. Journal of Alloys and Compounds, 2000, v.313, p.85-92.

6. N.Bukun, Y,Dobrovolsky, A.Levchenko, N.Leonova, E.Osadchii. Electrochemical processes of H2S detection in air and solution. Journal of Solid State Electrochemistry, 2003, v.7, p.122-124.

Abstract

7. V.I.Shtanov. Single crystal formations conditions in the case of Bridgman technique. Crystallography Reports, 2004, v.49 (in press)

8. L.V.Yashina, E.V.Tikhonov, V.S.Neudachina, T.S.Zyubina, A.N.Chaika, V.I.Shtanov, S.P.Kobeleva, Yu.A. Dobrovolsky. The oxidation of PbTe(100) surface in dry oxygen. Surface and Interface Analysis, 2004 (in press)

Abstract

Diploma thesis

Tikhonov E.V.(2003, Study of oxidation PbTe surface by X-Ray photoelectron spectroscopy)

PhD thesis

Shatalova T.B.(2003, Preparation and physicochemical properties of solid solutions Pb1-xGexTe and Sn1-xGexTe)

Projects:

2003-2005

Grant of Russian Foundation of Basic Researches The reactivity of NaCl-structural type nonstoichiometric semiconductors in heterogeneous reactions (03-03-32301)

2003

Impurity charge state, surface core level shifts and surface oxidation of (100) PbTe(X) surface (X=Ge,Ga,In) beamtime at BESSY II in Russian-German Laboratory

2004

The behaviour of H2S molecules at PbS(100) fresh and oxidised surfaces (in cooperation with Dr. Puettner, Freue Univesitaet Berlin) beamtime at BESSY II in Russian-German Laboratory


Joint Semiconductors Surface Study group: research sketches

The Joint Semiconductors Surface Study (JSSS) group was developed on the base of Inorganic Chemistry division, Chemistry dept. of M.V. Lomonosov Moscow State University. It includes also specialists from three different academician institutes RAS. Our group is aimed at studying the surface properties and reactivity of A4B6 semiconducting materials and their solid solutions. They are widely used in IR optoelectronics and for thermoelectrics development. The experiments are carried out using single crystals, which are obtained at MSU by different growth techniques, namely, the Bridgman and the VLS methods. In order to obtain single crystals being both structurally and compositionally perfect, one has to know precisely the phase diagrams of the systems under study. At MSU the binary, ternary and quasiternary phase diagrams of A4B6-based systems are also studied using thermal analysis techniques.

The schematic sketch of VLS growth using 3-phase source.

The surface analysis techniques used for the investigations are various spectroscopic (XPS, AES, AR XPS, UPS, EELS), microscopic (STM) and diffraction (LEED) methods. Most of the experiments are performed using ESCALAB MKII and ESCALAB 5 spectrometers.

The main research topics of surface studies are:

The results of the surface reactions studies are important both for semiconductor device preparation and exploitation, and A4B6-based sensors development, the latter being fulfilled at the Institute of Problems of Chemical Physics RAS.

All the above mentioned surface investigation techniques are applied to study the influence of both isovalent (Ge,Sn) and heterovalent (Ga,In) doping on the oxidation kinetics and surface reactivity of materials on the base of lead chalcogenides.

PbX (X=S,Se,Te) surface properties and reactivity are also studied by means of quantum chemical modeling using cluster and slab models. The calculations of the structures and interaction parameters are made within the framework of PM3 method and the density functional theory using three-parameter potential B3LYP with LanL2DZ plus polarization basis and effective core potential LanL2 for Pb, Se, Te atom and the basis 6-31G** for O, S and H atoms. The MOPAC2002 and GAUSSIAN-98 packages are employed for the calculations.

Structures and relative energies of local minima and transition states on the potential energy surface for (PbTe)4 cluster+O2 reaction. The relative energies calculated at B3LYP/LanL2DZ* level are given in kcal/mol. The effective atom charges (by Mulliken) are shown in square brackets. Bond lengths are given in angstroms.