Abstract
This study made an attempt to understand and control the heteroepitaxial growth of GaN from the view of the essential behaviors of crystal growth. Through a comparison of the nonpolar, polar and semipolar GaN epitaxial film, the influence of lateral growth on the surface pit formation mechanism has been investigated. For a-plane GaN, the lateral growth velocities of the less inclined {20-21} and {11-22} facets are approaching to the velocity of {10-11} facet under high temperature, so that the surface pit was transformed from a triangular shape to a pentagonal one. For c-plane GaN, the size of the surface pit produced by screw dislocation is determined by the lateral growth of the pit facets. A slow lateral growth rate of the inclined facets {10-11} compared with the vertical growth rate of (0001) facet under low V/III ratio would enlarge the pit size. For (11-22) semipolar GaN, surface pit is rarely observed, because the vertical growth velocity of {11-22} plane is slow compared with the lateral growth rate of the inclined facets, such as {11-20} and (0001).DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12931
Highlights
This study made an attempt to understand and control the heteroepitaxial growth of GaN from the view of the essential behaviors of crystal growth
In the metal organic chemical vapor deposition (MOCVD) growth of GaN [5 – 7] epitaxial growth cannot be completely one by one atomic layers, island growth mode is highly preferred [6 – 9]; as a result, the lateral growth of these islands critically determines the physical properties of the epitaxial film
Since surface morphology is one of the most important factors in evaluation of crystal quality, we have studied in this paper the influence of lateral growth on the surface morphology
Summary
This study made an attempt to understand and control the heteroepitaxial growth of GaN from the view of the essential behaviors of crystal growth. Through a comparison of the nonpolar, polar and semipolar GaN epitaxial film, the influence of lateral growth on the surface pit formation mechanism has been investigated. For [11,12,13,14,15,16,17,18,19,20,21,22] semipolar GaN, surface pit is rarely observed, because the vertical growth velocity of {11-22} plane is slow compared with the lateral growth rate of the inclined facets, such as {11-20} and (0001). Lateral growth often refers to the preferential growth along certain crystal planes that perpendicular to the main growth direction due to different surface energies. The TEM specimens were prepared by means of focused ion beam (FIB)
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