Enhanced performance of silicon quantum dot light-emitting diodes grown on nanoroughened silicon substrate

We report the effect of a nanoroughened Si substrate on silicon quantum dot (Si QD) light-emitting diodes (LEDs). The electroluminescence of Si QD LEDs grown on the nanoroughened Si substrate was remarkably improved by 493% at an injection current of 90 mA compared to those of Si QD LEDs grown on the flat Si substrate. The electrical and optical enhancements were attributed to the enhanced inhomogeneous local electric field on the nanoroughened Si surface and the angular randomization of photons emitted from Si QDs at the nanoroughened surface of silicon nitride layer containing Si QDs.