An infrared absorption study of lithium in silicon

Abstract

Lithium, lithium oxide, and the group V elements, phosphorus, arsenic, antimony, and bismuth, when present in silicon as impurities, act as "shallow" donors (2, 7, 11). These donors have electrons which are bound so loosely that they may be thermally excited into the conduction band at less than room temperature. The excited bound states and, less precisely, the ground states of these electrons are understood within the framework of the shallow donor theory. A transition from the 1S(E+T₁) state of lithium oxide, which lies 7.7± .1 mev above its ground state, to the 2P± state was observed. When phosphorus and lithium were both present as donors in silicon, the phosphorus peaks normally occurring at 34.4 mev, 2PO and 39.2 mev, 2P±, seemed to be split by .8 ± .1 mev. An upper limit of 10¹⁴/ cc was observed for the oxygen content of zone refined silicon using Pell's (15) value for the dissociation constant, C.