Optical excitation spectra of selenium-doped silicon

Infrared absorption spectra of selenium-doped silicon contain excitation lines indicative of three selenium donor centers with first (and second) ionization energies at 116(214), 206.5(388) and 306.7(589) meV. Cooling rate effects on the absorption strengths establish that the 306 meV center is due to isolated selenium and that the two lower energy centers are due to selenium complexes. The results suggest close similarities with those for sulfur-doped silicon. Selenium-doped samples containing & times; 10¹⁴ cm^-3 boron exhibit spectra of isolated boron and of ionized donor centers; boron apparently acts as an isolated (compensating) acceptor and is not a constituent in either selenium complex.