Papers by Keyword: Terahertz Emission

Abstract: Terahertz electroluminescence of unipolar n⁺⁺-n⁻-n⁺ SiC structures at helium temperatures and I-V characteristics of bipolar n⁺⁺-π-n⁺ SiC structures with natural superlattices at 300~K at strong electrical fields are studied. The properties of the THz electroluminescence and I-V characteristics testify that these phenomena due to Bloch oscillations.

Abstract: The comprehensive study of the terahertz electroluminescence caused by the Bloch oscillations of the electrons in the natural superlattices of 8H-, 6H-SiC with strong electrical field applied along the natural superlattices axis is represented. The electroluminescence spectra become much broader when the bias field exceeds substantially the threshold field of the Bloch oscillations. This spectral broadening can be explained by an appearance of a new spectral line that is much wider and its maximum is localized at higher energy than lines induced by Bloch oscillations. This line has no link with the Bloch oscillations mechanism and it is a result of the presumed changes in the SiC conduction band with complex electron spectrum structure by applied electrical field.

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.