Lasing with Pumping Levels of Si Nanocrystals on Silicon Wafer

Abstract

It is reported that the silicon nanocrystals (NCs) are fabricated by using self-assembly growth method with the annealing and the electron beam irradiation processes in the pulsed laser depositing, on which the visible lasing with higher gain (over 130 cm−1) and the enhanced emission in optical telecommunication window are measured in photoluminescence (PL). It is interesting that the enhanced visible electroluminescence (EL) on silicon nanocrystals (Si-NCs) is obviously observed by the naked eyes, and the light-emitting diode (LED) of the Si-NCs with external quantum efficiency of 20% is made on silicon chip in our laboratory. A four-level system is built for emission model in nanosilicon, in which the PL and EL measurement and transmission electron microscope (TEM) analysis demonstrate that the pumping levels with shorter lifetime from the rising energy of the Si quantum dots due to the quantum confinement effect occur, and the electronic localized states with longer lifetime owing to impurities bonding on Si-NCs surface are formed in the crystallized process to produce the inversion of population for lasing, where the optical gain is generated.

Localized states and quantum effect of photo-generated carriers in photovoltaic system

“…Recently, significant effort has been focused on enhancing the light absorption by nanoscale light trapping using nanowires, nanocones, nanodomes and nanoholes 22 – 31 . Despite the exciting success in light trapping, the power conversion efficiency of nano-structured Si solar cells, however, remain lower efficiency for the thick devices and the thin devices 32 , 33 . The Si solar cells with nanostructures are not efficient because of severe Auger recombination.…”