The photoluminescence properties of nanocomposite thin films containing InN quantum dots embedded in Si matrix

Nanocomposite thin films containing indium nitride (InN) quantum dots (QDs) embedded in silicon (Si) matrix were prepared by the target-attachment sputtering method. X-ray photoelectron spectroscopy confirmed the presence of hexagonal InN phase in the samples and transmission electron microscopy revealed the single-crystalline InN QDs with the diameters ranging from 3.0 to 5.6 nm finely dispersed in Si matrix. The room-temperature photoluminescence (PL) analysis observed a sole emission with the peak at about 1155 nm (∼1.08 eV) for all samples in the measured wavelength range of 900 to 1600 nm. Such a PL emission was ascribed to the pinning effect of conduction band at the Fermi stabilization level of InN. Further, the PL intensity increased with the increase of incident laser power, implying the PL emission is correlated with the band-to-band transition in InN. The low-temperature PL analysis observed the dramatic increase of PL intensity and the shift of peak location toward the short wavelength side when the temperature was decreased. Meanwhile, the symmetry of emission peaks gradually improved owning to the suppression of the band tailing and thermal population effects.