Excimer Laser Annealing with a Line Beam for Improvement of Structural and Optical Properties of Polycrystalline GaN

Abstract

Polycrystalline gallium nitride (GaN) thin films of thickness 3.0 mm grown on silica glass substrates were annealed by a line beam of a KrF excimer laser under vacuum. The applied laser energy density was in the range of 300-600 mJ/cm 2 . Photoluminescence (PL) and X-ray diffraction (XRD) measurements have been carried out to investigate the laser annealing effects in polycrystalline GaN films grown on silica glass by metal-organic chemical vapor deposition (MOCVD). The results of the PL spectra revealed that the intensity of the band edge (BE) emission for the GaN on silica glass annealed at a laser energy density of 500 mJ/cm 2 was increased by as much as about 1.5 times in comparison with the as-grown GaN. It was found that the full width at half maximum (FWHM) of the XRD for laser annealed GaN film at a high laser energy density, 500 mJ/cm 2 , with 200 pulses was smaller than that of the as-grown GaN. These results indicate that the structural and optical properties of the poly-GaN layers grown on silica glass substrate are improved by the laser annealing method.

Effect of high temperature annealing on strain and band gap of GaN nanoparticles

“…GaN and its related alloys have been used in a variety of light-emitting devices and electronic devices. Although heteroepitaxially grown devices have been commercialized, more technological innovations, such as ultraviolet (UV) light irradiation method, [1] hydrogenation method during growth, [2] laser annealing method, [3] isoelectronic in-doping method, [4] hightemperature rapid thermal annealing method, [5] etc., are needed to realize highly efficient, highly reliable, and low-cost devices. In general, the methods cited above can lead to some slight improvement in the GaN crystal quality.…”

Undoped p-type GaN1–xSbx alloys: Effects of annealing

“…14 A modest amount of studies on the effect of annealing polycrystalline GaN and its alloys have been conducted. [15][16][17][18][19] Recent studies indicate that annealing improves the structural and optical properties of polycrystalline GaN layers by re-crystallizing the GaN grains. For polycrystalline InGaN thin films, rapid thermal annealing (RTA) experiments found the crystallinity to be improved by annealing and the resistivity to be reduced by two orders of magnitude due to the annealing-induced increase in the carrier concentration.…”

Laser processing of Ga2O3 micro and nanostructures

“…The ultrafast melting and resolidification sequence by pulsed laser annealing has been extensively studied with various time-resolved optical [207], electrical [208] and X-ray [209] techniques. In addition, an improvement in the structural and optical properties of polycrystalline GaN on silica substrates by excimer laser annealing has been recently demonstrated by Kim et al [210]. Conventional thermal annealing requires the samples to be heated to high temperature for sufficiently long time for thermal diffusion of the defects to occur.…”