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The past results related to the main features of formation of structural V-defects in
polar GaN(0001) and semi-polar epitaxial GaN films are presented. The GaN films have been
synthesized by hydride-chloride vapor-phase epitaxy (HVPE) on two different substrates
Si(111) and Si(100) with an intermediate nano-SiC epitaxial layer. The nano-SiC layer has
been formed by a method of atom substitution on the Si substrate. The experimental studies
have demonstrated that V-defects on the surface of GaN(0001) films are regular hexagons of
30 µm in size, while on the surface of GaN V-defects are of the order of 1 µm. It was found
that V-defects on the semipolar face are extended along the
(1123).
direction. The size of
oblique facets of V-defects on the surface of polar GaN(0001) is of about 1 µm, while on the
surface of semipolar GaN
(1101)
layer they are much less, measuring about 150 nm, on the
average. On the basis of thermodynamics, the mechanisms of nucleation of V-defects on polar
and semipolar faces of GaN epitaxial films are elucidated, and the criteria of the formation of
V-defects are theoretically derived. A good qualitative agreement between the experimental
results and the theoretical model was found.
Keywords: GaN films; semi-polar GaN; V-defects; etch pits; silicon carbide films; heterostructures; wide-band semiconductors; nanostructures |
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