Influence of the Position of the Fermi Level on an Infrared Active Defect in Irradiated Silicon

Influence of the position of the Fermi level on the infrared active defect,so-called higher order bands(HOB),has been investigated in neutron irradiated silicon by using infrared absorption and Hall-effect measurements at low temperatures.The optical excitation and the introduction of thermal donors(TD)effectively alter the position of the Fermi level.Similar optically active behaviors between the HOB and TD^(+) have been observed.It is suggested strongly that the mechanism of the Fermi level influencing on the HOB is the same as that of the TD^(+).