A. Mogilatenko^a,b,A. Knauer^a, U. Zeimer^a, C. Hartmann^c, H. Oppermann^c, M. Weyers^a

Published in:

J. Cryst. Growth, vol. 462, pp. 18-23 (2017).

Abstract:

The effect of Si doping on defect density in AlN layers grown on sapphire was analysed. Si concentration in the range of 10¹⁹cm^-3 leads to dislocation line inclination in AlN layers with a threading dislocation density of 3×10¹⁰cm^-2. Overgrowth of Si doped AlN layers by non-intentionally doped AlN results in a reduction of threading dislocation density by a factor of two. In contrast, an increase of the Si concentration to an order of 10²⁰cm^-3 leads to a structural degradation of the AlN layers. The degradation process takes place through transformation to columnar-like growth. In a second experiment the AlN/AlN:Si/AlN layers with a decreased defect density were trench-patterned and used for subsequent epitaxial lateral overgrowth. In comparison to the epitaxial lateral overgrowth of non-intentionally doped AlN templates, the use of the AlN templates containing an AlN:Si interlayer allows to reduce the threading dislocation density in the defect-rich regions above the ridges in 6 µm thick epitaxial laterally overgrown AlN by a factor of 2.5.

Keywords:

A1: Line defects; A1: Doping; A3: Metalorganic chemical vapour deposition; A3: Epitaxial lateral overgrowth; B1: Aluminium nitride.

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