Selenium Selenium Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It rarely occurs in its elemental state or as pure ore compounds in the Earth's crust. Selenium (from Ancient Greek (selḗnē) "Moon") was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium (named for the Earth). Selenium is found in , where it
Germanium-tin Germanium-tin Germanium-tin is an alloy of the elements germanium and tin, both located in group 14 of the periodic table. It is only thermodynamically stable under a small composition range. Despite this limitation, it has useful properties for band gap and strain engineering of silicon integrated optoelectronic and microelectronic semiconductor devices. Germanium-tin alloys must be kinetically stabilized in order to prevent decomposition. Therefore, low temperature molecular beam epitaxy or chemical vapor deposition techniques are typically used for their synthesis. Germanium-tin alloys have higher carrier mobilities than either silicon or germanium. Therefore it has been proposed that they can be used