Theory of Optical Absorption by Vibrations of Defects in Silicon

Abstract

Using the theory of the nature of lattice vibrations around an impurity of different mass in a cubic crystal, detailed calculations are made of the optical absorption expected from compensated group III and group V impurities in Si due to creation of single phonons. Provided good compensation can be achieved it appears that this absorption should be clearly visible in concentrations of about 1019 cm-3. The calculated frequency spectrum of Johnson is used and it is shown that localized and band modes will give comparable effects, which change considerably with the mass of the impurity.