Infrared excitation spectrum of thallium‐doped silicon

The excitation spectrum of thallium‐doped silicon has been measured in crystals doped to a level of 5×1016 Tl/cm3. The spectrum is characteristic of an effective‐mass‐like acceptor with an optical ionization energy of 0.246 meV. The peak optical cross section was estimated to be 2.6×10−17 cm2.