Papers by Author: Sergeij G. Pavlov

Abstract: Terahertz-range photoluminescence from silicon-germanium crystals and superlattices doped by phosphor has been studied under optical excitation by radiation from a mid-infrared CO2 laser at low temperature. SiGe crystals with a Ge content between 0.9 and 6.5 %, doped by phosphor with a concentration optimal for silicon laser operation, do not exhibit terahertz gain. On the contrary, terahertz-range gain of ~ 2.3 - 3.2 cm-1 has been observed for donor-related optical transitions in Si/SiGe strained superlattices at pump intensities above 100 kW/cm2.

Abstract: Silicon crystals, doped with moderate concentration of magnesium or lithium, have been grown for application as optically pumped donor silicon lasers for the terahertz spectral region. The pedestal growth technique accompanied with axial-loaded dopant pills enabled manufacturing of large silicon crystals with a homogeneous donor distribution in the range from 1014 to 1016 cm-3, as required for intracenter silicon lasers. Terahertz-range photoluminescence from the grown crystals has been observed.

Abstract: The performance of optically pumped terahertz silicon lasers with active media made from mono- and polycrystalline silicon doped by phosphorus has been investigated. The polycrystalline silicon samples consist of grains with a characteristic size distribution in the range from 50 to 500 m. Despite of significant changes of the principal phonon spectrum and increased scattering of phonons at grain boundaries, the silicon laser made from polycrystalline material has a laser threshold and an operation temperature only slightly worse than that of monocrystalline silicon lasers.