An Inversion Domain Superlattice of 4H-SiC for Room-Temperature and Tunable Terahertz Generation

Abstract

An inversion domain superlattice of 4H-SiC is designed theoretically for generating room-temperature and tunable terahertz (THz) radiation via the combination of the density functional theory and classic coupled-wave equations. For such symmetric structures, our calculations indicate that only the Raman and infrared active E′ modes contribute to the THz parametric generation in the frequency range of 0.2–3.3 THz. The lowest E′ modes correspond to the relative shearing movement of the C–C and Si–Si double layers, and its energy can be adjusted to the sub-THz region by increasing length of the superlattice unit cell. With a pump source operating at 1.064 μm, the maximal THz gain in the process of stimulated polariton scattering was obtained to be 1.26 cm–1 at room temperature for a y-plate superlattice, which is slightly lower than that in the commonly used LiNbO3 under the same pump power. Such inversion domain superlattices of 4H-SiC with different unit lengths can be prepared experimentally via the atomi...