Blue Light Emission from PECVD Deposited Nanostructured SiC

Abstract

AbstractExperimental data on the room temperature blue light emission from nanocrystalline silicon carbide (nc-SiC) films are presented. The silicon carbide films were deposited on silicon substrates with a plasma enhanced chemical vapor deposition (PECVD) reactor from methyltrichlorosilane at substrate temperature in the range of 200-350°C. The film deposited at 350°C is nanostructured and X-ray diffraction proves the presence of the 3C-SiC crystallites. Infrared absorption spectroscopy in the region of Si-C, C-H, C-O, Si-H and Si-O bonds show the corresponding absorption bands. X-ray photoelectron spectroscopy studies confirm this bond picture. Photoluminescence was measured at 77 and 300 K. The bright blue emission has a double-peak structure at 415 and 437 nm. To clarify the origin of such an emission, tight binding molecular dynamics (TB-MD) simulations of several SiC and Si nanoclusters were carried out. Based on the temperature dependence of the photoluminescence and on the simulation data, a possible model of radiative recombination in nc-SiC films was proposed. According to this model, the emission bands at 415 and 437 nm are assigned to band-to-band and band-to-tail recombination in the nanocrystallite core. The recombination at band tails of the interface and Si-C-O-H amorphous tissue gives rise to a shoulder around 470 nm.