In this study, we investigate a novel simple methodology to synthesize gallium nitride nanoparticles (GaN) that could be used as an active layer in light-emitting diode (LED) devices by combining the crystal growth technique with thermal vacuum evaporation. The characterizations of structural and optical properties are carried out with different techniques to investigate the main featured properties of GaN bulk alloys and their thin films. Field emission scanning electron microscopy (FESEM) delivered images in bulk structures that show micro rods with an average diameter of 0.98 µm, while their thin films show regular microspheres with diameter ranging from 0.13 µm to 0.22 µm. X-ray diffraction (XRD) of the bulk crystals reveals a combination of 20% hexagonal and 80% cubic structure, and in thin films, it shows the orientation of the hexagonal phase. For HRTEM, these microspheres are composed of nanoparticles of GaN with diameter of 8–10 nm. For the optical behavior, a band gap of about from 2.33 to 3.1 eV is observed in both cases as alloy and thin film, respectively. This article highlights the fabrication of the major cubic structure of GaN bulk alloy with its thin films of high electron lifetime.
In this study, we investigated an innovative method for the fabrication of nanostructure bulk alloys and thin films of indium gallium nitride (InxGa1-xN) as active, thin films for light-emitting diode (LED) devices using both crystal growth and thermal vacuum evaporation techniques, respectively. These methods resulted in some tangible improvements upon the usual techniques of InxGa1-xN systems. A cheap glass substrate was used for the fabrication of the LED devices instead of sapphire. Indium (In) and Gallium (Ga) metals, and ammonia (NH3) were the precursors for the alloy formation. The alloys were prepared at different growth temperatures with compositions ranging from 0.1≤x≤0.9. InxGa1-xN alloys at 0.1≤x≤0.9 had different crystallinities with respect to X-Ray diffraction (XRD) patterns where the energy bandgap that was measured by photoluminescence (PL) fell in the range between 1.3 and 2.5 eV. The bulk alloys were utilized to deposit the thin films onto the glass substrate using thermal vacuum evaporation (TVE). The XRD thin films that were prepared by TVE showed high crystallinity of cubic and hexagonal structures with high homogeneity. Using TVE, the InxGa1-xN phase separation of 0.1≤x≤0.9 was eliminated and highly detected by XRD and FESEM. Also, the Raman spectroscopy confirmed the structure that was detected by XRD. The FESEM showed a variance in the grain size of both alloys and thin films. The InxGa1-xN LED device with the structure of glass/GaN/n-In0.1Ga0.9N:n/In0.1Ga0.9N/p-In0.1Ga0.9N:Mg was checked by the light emitted by electroluminescence (EL). White light generation is a promising new direction for the fabrication of such devices based on InxGa1-xN LED devices with simple and low-cost techniques.
In0.1Ga0.9N thin film was grown on a cheap glass substrate by the Nd:YAG pulsed laser deposition technique. The In0.1Ga0.9N thin films show the semi-crystalline structure as observed with X-ray diffraction (XRD). The surface morphology has a non-dense layer with both scattered nanospheres and agglomerated particles. These nanospheres tended to grow randomly on the glass substrate, as observed with field emission scanning electron microscopy (FESEM). The direct bandgap energy for In0.1Ga0.9N thin film was 2.08 eV, which is calculated using photoluminescence (PL) measurements. The Raman measurements illustrated two sets of phonon modes as A1(LO) and E2 high vibrational modes that are observed. The resonance behavior of the A1(LO) mode is experimentally verified and studied under laser light energy of 532 nm.
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