Metalloid silicon, germanium, arsenic, antimony, and tellurium are commonly recognised as metalloids. Depending on the author, one or more from selenium, polonium, or astatine are sometimes added to the list. Boron sometimes is excluded, by itself, or with silicon. Sometimes tellurium is not regarded as a metalloid. The inclusion of antimony, polonium, and astatine as metalloids has been questioned. Other elements are occasionally classified as metalloids. These elements include hydrogen, beryllium, nitrogen, phosphorus, sulfur, zinc, gallium, tin, iodine, lead, bismuth, and radon. The term metalloid has also been used for elements that exhibit metallic lustre and electrical conductivity, and that are
Silicon-germanium silicon-only technology. Silicon Germanium-on-insulator (SGOI) is a technology analogous to the Silicon-On-Insulator (SOI) technology currently employed in computer chips. SGOI increases the speed of the transistors inside microchips by straining the crystal lattice under the MOS transistor gate, resulting in improved electron mobility and higher drive currents. SiGe MOSFETs can also provide lower junction leakage due to the lower band gap value of SiGe. However, a major issue with SGOI MOSFETs is the inability to form stable oxides with silicon germanium using standard silicon oxidation processing. A silicon germanium thermoelectric device, MHW-RTG3, was used in the Voyager 1 and 2