Dynamics of nonequilibrium electrons on neutral center states of interstitial magnesium donors in silicon

Abstract

Subnanosecond dynamics of optically excited electrons bound to excited states of neutral magnesium donor centers in silicon has been investigated. Lifetimes of nonequilibrium electrons have been derived from the decay of the differential transmission at photon energies matching the intracenter and the impurity-to-conduction band transitions. In contrast to hydrogenlike shallow donors in silicon, significantly longer lifetimes have been observed. This indicates weaker two-phonon and off-resonant interactions dominate the relaxation processes in contrast to the single-intervalley-phonon-assisted impurity-phonon interactions in the case of shallow donors in silicon.

Relaxation of Coulomb States in Semiconductors Probed by FEL Radiation

“…The experimental methods being used for the investigations compose a very broad set of different techniques involving transport and optics and their combinations under various conditions. Last two decades the appearance of new user facilities based on THz free electron lasers (FELs) emitting high power short THz pulses provides the unique opportunity for studying of impurity centers in semiconductors under resonant excitation of chosen energy levels using single color pumpprobe technique [2][3][4]. In particular, the lifetimes of different donors and acceptors in silicon have been measured to localize the time scale of the existing relaxation rates.…”

“…Typical donor concentrations were in the range of N D =1-5×10 15 cm −3 . The samples were shaped into parallelepipeds with dimensions of ~7×5×2 mm 3 . Each sample was placed into the special module designed to apply uniaxial stress.…”