Structural and electrical characteristics of epitaxial GaN thin films grown using pulsed laser deposition assisted by an atomic nitrogen source

• Published in: Applied surface science 2001-06, Vol.177 (3), p.165-171
• Main Authors: Mérel, Philippe, Chaker, Mohamed, Tabbal, Malek, Pépin, Henri
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Epitaxial; Exact sciences and technology; GaN thin films; Hall effect; Laser deposition; Low-field transport and mobility; piezoresistance; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(01)00203-3

A deposition system combining pulsed laser deposition (PLD, cooled Ga target) and a source of atomic nitrogen was developed to grow epitaxial gallium nitride on sapphire. The layers obtained with this system were characterized using high-resolution X-ray diffraction, atomic force microscopy (AFM), Hall effect, and secondary ion mass spectroscopy (SIMS). It is found that the crystal quality greatly depends on the atomic nitrogen flux incident on the substrate during growth. After optimization of the atomic nitrogen-to-gallium flux ratio, samples showing very narrow GaN(0 0 0 2) rocking curves (full width at half maximum, FWHM=80 arcsec) have been synthesized at a low substrate temperature ( T s=750°C). Surface analysis of these thin films, using AFM, also show a very low roughness ( R rms=14 Å).