Lists of metalloids cluster. Cluster 1 (93%) = B, Si, Ge, As, Sb, Te; cluster 2 (44%) = Po, At; cluster 3 (24%) = Se; cluster 4 (9%) = C, Al; cluster 5 (5%) = Be, P, Bi; cluster 6 (3%) = Sn; and cluster 7 (1%) = H, Ga, S, I, Pb, Fl, Mc, Lv, Ts. The resulting geometric trend line has the formula y = 199.47e and an R value of 0.9962. The elements commonly classified as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. The status of polonium and astatine is not settled. Most authors recognise one or the
Silicon Hence pure silicon is an insulator at room temperature. However, doping silicon with a pnictogen such as phosphorus, arsenic, or antimony introduces one extra electron per dopant and these may then be excited into the conduction band either thermally or photolytically, creating an n-type semiconductor. Similarly, doping silicon with a group 13 element such as boron, aluminium, or gallium results in the introduction of acceptor levels that trap electrons that may be excited from the filled valence band, creating a p-type semiconductor. Joining n-type silicon to p-type silicon creates a p-n junction with a common Fermi level; electrons flow from