Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution
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We demonstrate the synthesis of GaN nanocrystals (NCs) with the sizes of less than the doubled exciton Bohr radius leading quantum confinement effects via a single-step technique. The generation of colloidal GaN nanoparticles (NPs) in organic solution through nanosecond (ns) and femtosecond (fs) pulsed laser ablation (PLA) of GaN powder was carried out. Ns PLA in ethanol and polymer matrix resulted in amorphous GaN-NPs with the size distribution of 12.4 ± 7.0 and 6.4 ± 2.3 nm, respectively, whereas fs PLA in ethanol produced colloidal GaN-NCs with spherical shape within 4.2 ± 1.9 nm particle size distribution. XRD and selected area electron diffraction analysis of the product via fs PLA revealed that GaN-NCs are in wurtzite structure. Moreover, X-ray photoelectron spectroscopy measurements also confirm the presence of GaN nanomaterials. The colloidal GaN-NCs solution exhibits strong blue shift in the absorption spectrum compared to that of the GaN-NPs via ns PLA in ethanol. Furthermore, the photoluminescence emission behavior of fs PLA-generated GaN-NCs in the 295–400 nm wavelength range is observed with a peak position located at 305 nm showing a strong blue shift with respect to the bulk GaN.
KeywordsGallium nitride nanoparticles Femtosecond/nanosecond pulsed laser ablation in organic solution Ultrasmall nanocrystal generation Photoluminescence
This work is supported by the Scientific Research Fund of Turgut Özal University under the project number of 001-04-2012. State Planning Organization (DPT) of Turkey is acknowledged for the support of UNAM-Institute of Materials Science and Nanotechnology. B.O. acknowledges partial support of TUBITAK (Project No: 113S223), The Turkish Academy of Sciences—Outstanding Young Scientists Award Program (TUBA-GEBIP), Bilim Akademisi—The Science Academy, Turkey under the BAGEP program, and METU Prof. Dr. Mustafa Parlar Foundation.
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