Crystal defect analysis in AlN layers grown by MOVPE on bulk AlN
J. Cryst. Growth, vol. 505, pp. 69-73 (2019).
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MOVPE growth of AlN layers on bulk AlN substrates with low threading dislocation density (< 105 cm-2) can result in enhanced defect formation. Chemo-mechanical polishing (CMP) of bulk AlN using colloidal silica sol can produce locally disturbed surface with SiOx residuals. These surface disturbances lead to generation of threading dislocations (∼108 cm-2) in homoepitaxially grown AlN layers. These dislocations show a tendency to form nano- and even micropipes, which may be associated with oxygen accumulation along the dislocation lines. As result, the subsequently grown AlGaN-based layer structures exhibit a high number of v-pits and micropipes. Inductively coupled plasma etching of AlN substrate surface prior to MOVPE growth results in clean AlN surfaces and improves the AlGaN layer quality.
a Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
b Humboldt University of Berlin, Institute of Physics, Newtonstr. 15, 12489 Berlin, Germany
c Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin, Germany
A1: Line defects; A3: Metalorganic vapor phase epitaxy; B1: Nitrides; B2: Semiconducting aluminium compounds.