Light emission of 2D photonic crystal based on nanocrystal-Si/SiO2 superlattice structure

Abstract

Because of the its indirect bandgap structure, it is a huge challenge to establish an efficient Si light emitting diode (LED) compatible with complementary metal-oxide-semiconductor (CMOS) process. In this paper, we provide an alternative route to overcome this difficulty based on the unique property of photonic crystals (PhC). A vertical-current-injection LED based on three-dimensional-confined structures with triangular-lattice air-hole PhC patterns has been fabricated with enhanced light extraction from the active region (i.e., silicon-rich-oxide/SiO2 multilayer stack). The intensity and profile of photoluminescence (PL) and electroluminescence (EL) has been found to be efficiently modulated by controlling the optical modes of the periodic arrays via varying their structural parameters. It provides a convenient way of redistributing the light energy in desired form and orientation. With optimized lattice constant/radius ratio, significant enhancement up to ∼7 times in both PL and EL emissions can be obtained. The mechanisms for different enhancement features have also been theoretically analyzed based on coherent scattering and quantum electrodynamics effects, which is well consistent with the experiment observation.