Difference in the IR absorption of thermal donors in n-Si and p-Si

Abstract

The low-temperature thermal donors in silicon are currently an object of investigation; however, their nature has not been reliably established. The presence of such thermal donors in silicon with concentrations N /SUB d/ 10 U cm T results in the appearance of specific bands in the IR absorption spectrum. These bands are attributed to the photoexcitation of electrons found in the levels of the thermal donors. However, according to current theories, such absorption is possible in samples of p-Si only under the conditions of additional optical pumping, which provides for the nonequilibrium filling of the energy levels of the thermal donors. This paper is devoted to a systematic investigation of the absorption by thermal donors in n-Si and p-Si subjected to isothermal heat treatment at a temperature of 450C for various time periods. In particular an attempt is made to evaluate the validity of the interpretation of the absorption by thermal donors in p-Si as proposed by Pajot et. al.