Impact of annealing temperature on structural, electrical and optical properties of epitaxial GaN thin films grown on sapphire substrates by PA-MBE

2015/09/01 by Biswas, Mahitosh
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)

paper · doi:10.48550/arxiv.1509.00416

Abstract

We report epitaxial growth and characterization of GaN thin films on sapphire (0001) substrates using low temperature GaN intermediate layer by plasma assisted molecular beam epitaxy (PA-MBE) technique. As grown and annealed GaN thin films were studied by high- resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), Hall Effect and photoluminescence (PL). It has been found that there is a significant improvement in the quality of the GaN films after annealing at 725 ° C in terms of electron mobility, full width at half maximum (FWHM) of omega (ω) scan around (0002) XRD peak of GaN films. Screw dislocation density obtained from the FWHM of GaN (0002) ωscan and etch pitch density calculated from AFM image are 6.4 × 10⁸ cm^-2 and 5.1× 10⁸ cm^-2 respectively. In PL measurement, FWHM of near band edge (NBE) peak of GaN films has been found to be 30 meV.

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