Measuring dislocation densities in nonpolar a-plane GaN films using atomic force microscopy

M A Moram (1) , C F Johnston (1) , M J Kappers (1) , C J Humphreys (1)

1 Dept. Materials Science & Metallurgy

Dislocation densities in nonpolar GaN films were determined using atomic force microscopy (AFM) by counting pits in the GaN surface revealed by a SiH 4 surface treatment. This treatment increased the number of pits detected by a factor of 2 compared to the untreated surface. AFM and transmission electron microscopy analysis of a series of SiH 4 -treated calibration samples indicated that surface pit and dislocation densities corresponded well up to a dislocation density of ~6 x 10 9 cm -2, above which surface pit overlap meant that dislocation densities determined by AFM were underestimated. For all samples with dislocations densities below 6 x 10 9 cm -2, spatial analysis of the surface pit positions showed that dislocations typically accumulated in bands at island coalescence boundaries.

Mots clés: A1. Atomic force microscopy; A1. Line defects; A1. Planar defects; A3. Metalorganic vapour phase epitaxy; B1. Nitrides; B2. Semiconducting III-V materials PACS codes: 61.72.Ff; 61.72.Lk; 61.72.Nn; 61.72.uj; 68.37.Ps; 81.05.Ea

M A Moram, C F Johnston, M J Kappers, C J Humphreys. Measuring dislocation densities in nonpolar a-plane GaN films using atomic force microscopy. Journal of Physics D: Applied Physics, 2010, 43 (5), pp.55303. ⟨10.1088/0022-3727/43/5/055303⟩. ⟨hal-00569753⟩