Continuous downscaling of device dimensions in microelectronics combined with an increase of memory capacity and device speed caused a great demand for application of thin film technologies. For those materials, which are intensively used in low-scale applications, some of the critical material properties are electrical resistivity, compatibility with self-aligned silicidation process (SALICIDE technology), thermal, mechanical and chemical stabilities, etc. Furthermore, the use of environmentally friendly and cheap materials is important for industrial applications.
In recent decades strong interest has been drawn to the class of materials known as silicides [1, 2], which are chemical compounds of silicon with different metals. Among them are transition metal silicides (PtSi, TiSi2, CoSi2, NiSi, MnSi1.7, CrSi2, FeSi2, etc.) [3, 2]. Thin film growth of the silicides on (001)Si substrates is important for many industrial applications.The electrical properties of metallic silicides, such as PtSi, TiSi2, CoSi2, NiSi, as well as their excellent compatibility with Si have made them attractive for the use in submicron MOSFET structures, Schottky barriers in silicon integrated circuits, as ohmic contacts and in heterojunction bipolar transistors (HBT). Semiconducting silicides, such as the higher manganese silicides (HMS) MnSi1.7, CrSi2, ?-FeSi2, ReSi1.75, Ru2Si3, OsSi2 and Ir3Si5, have a high potential for thermoelectric applications [4, 5]. Additionally, such semiconducting silicides as FeSi2, MnSi1.7 and Ru2Si3 are reported to have a direct band gap, which makes them attractive for optoelectronic application [2, 5]. Most of the recent investigations of semiconducting silicides have been focused on the thin film formation of FeSi2 and CrSi2, whereas less attention has been drawn to the thin film growth of MnSi1.7, ReSi1.75, Ru2Si3 and others.
This work reports on the structure characterization of semiconducting HMS films on (001)Si. Semiconducting higher manganese silicides MnSix with a composition x varying from 1.67 to 1.75 are the most promising thermoelectric silicides of p-type.Among the semi-conducting silicides the doped HMS show the highest value of figure of merit that has been published [4, 6]. According to results of X-ray diffraction there exist a number of tetragonal HMS phases (Mn4Si7, Mn11Si19, Mn15Si26, etc.), which differ slightly in their compositionx (for details see chapter 2). These materials possess a good stability at high temperatures which makes them promising for the high-temperature thermoelectric applications. Besides, they are non-toxic and cheap [7]. Additionally, HMS are known to exhibit an anisotropy of their electrical and thermoelectric properties which suggests their application foranisotropic thermoelectrics [8].
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Electron Microscopy Characterization of Manganese Silicide Layers on Silicon
