Stoichiometry detuned silicon carbide as an orange and white light band solid-state phosphor

Abstract

A broadband orange and white light band solid-state phosphor from stoichiometry detuned amorphous silicon carbide (a-Si_xC_1−x) films with buried SiC and Si nanocrystals (SiC- and Si-ncs) is investigated. Such a semiconductor quantum dot embedded solid-state phosphor is synthesized by plasma-enhanced chemical vapor deposition with detuning of the fluence ratio g = [CH₄]/[SiH₄]. To modify its emitting color, the a-Si_xC_1−x films are grown with g = 40 to g = 70% for detuning its composition ratio from 0.74 to 0.62. After annealing at 1100 °C, a significant Raman scattering peak at 510 cm⁻¹ confirms the self-aggregation of Si-ncs with average sizes around 4.2 ± 0.5 nm, and the other two intensive transverse and longitude optical mode Raman scattering peaks at 744 and 933 cm⁻¹ verify the existence of nano-scaled 3C-SiC-ncs with the grain size reduced to 2.4 ± 0.3 nm after annealing. Under a gallium nitride laser diode illumination, the 3C-SiC-nc and Si-nc co-embedded a-Si_xC_1−x based solid-state phosphor grown at g = 60% and annealed at 1100 °C can provide intense orange or white-light emissions with a broadened linewidth of 200 nm. The emission centered at 485 nm is contributed by the self-trapped excitons surrounded at 3C-SiC-nc surface, whereas another emission peak at 580 nm is due to the quantum confined Si-ncs.