Abstract

In the first experimental search for persistent spectral hole burning in an elemental semiconductor, we examined a variety of electronic defects in Si and in a Si:Ge alloy. No persistent spectral changes have been observed for Be-Li, Se⁰, or thermal donors in Si; however, spectral holes which persist for ~5 ms have been produced in the 1s-2p absorption lines of a sulfur-hydrogen complex in Si. The addition of 0.7% Ge to the Si host ensures that an inhomogeneously broadened system is being studied. Measurements combining a CO₂ laser pump with a Fourier transform spectrometer probe reveal that the hole burning is due to migration of electrons from the S-H centers to shallow traps. The large observed hole width (4.6 cm⁻¹) is attributed to spectral diffusion by resonant excitation transfer. The hole burning behavior of the 2p_± line is temperature independent below 30 K, whereas the hole burning of the 2p₀ line exhibits strong temperature dependence, suggesting that the ionization of the laser-excited centers in the 2p_± hole burning process occurs via energy transfer between neighboring excited centers rather than by thermal ionization.

© 1987 Optical Society of America