Spectral- and time-resolved electroluminescence of silicon nanocrystals based light emitting devices

In this work we study the electroluminescence (EL) from a high efficiency multilayered silicon nanocrystals light emitting diode. The spectral analysis of EL under dc condition shows a spectrally modulated optical emission. Through reflectivity measurements we evaluated the effects of interference on the EL lineshape due to device structure and ascribed the emission to recombination in size dispersed silicon nanocrystals (Si-NCs). By studying the time resolved current–voltage I–V and EL-V, we evidenced that injected carriers are both accumulated separately and concurrently in Si-NCs. At the bias transition the accumulated carriers either are extracted from the gate oxide giving rise to a short current pulse or they diffuse to large Si-NCs giving rise to an EL overshoot which decays with µs time constant.