Abstract
The low-temperature (∼5 K) phonon-assisted relaxation of the 2 state of phosphorus donors in isotopically pure, monocrystalline Si has been studied in the time domain using a pump-probe technique. The lifetime of the 2 state in Si:P is found to be 235 ps, which is 16 larger than the lifetime of a reference Si:P sample with a natural isotope composition. The interaction of the 2 state with intervalley -type longitudinal acoustic and -type transverse acoustic phonons determines its lifetime. This interaction, which depends on the homogeneity of the crystal, becomes weaker in Si because of its more perfect crystal lattice compared to natural Si, and this leads to a longer lifetime. The difference between the linewidths of the 1() → 2 transition in Si:P and natural Si:P is more than a factor of two. It follows that linewidth broadening due to isotopic composition is an inhomogeneous process.
- Received 22 April 2013
DOI:https://doi.org/10.1103/PhysRevB.88.035201
©2013 American Physical Society