Nano-structured Metal-Oxide-Semiconductor Devices for Efficient Band-edge Electroluminescence

摘要

We report that electroluminescence (EL) at Si bandgap energy is significantly enhanced from the nano-structured metal-oxide-semiconductor (MOS) devices on silicon. The nano-structure is constructed by inserting SiO_2 nanoparticles with the size of 12 nm in the oxide layer. The measured EL efficiency of the nano-structured MOS devices is enhanced to be near 10~(-4), which exceeds the limitation imposed by the indirect bandgap nature of silicon. We also observed the nearly lasing behaviors such as the threshold and resonance modes in the EL characteristics. The enhanced EL efficiency is attributed to simultaneous localization of electrons and holes to form exciton by nano-structure. This causes the process of the phonon-assisted radiative recombination of electron-hole pair more like two-particle (exciton-phonon) collision than three-particle (electron-hole-phonon) collision.