Young's modulus extraction of epitaxial heterostructure AlGaN/GaN for MEMS application

This paper presents a Young's modulus extraction method for thin film group III-nitrides materials such as GaN, AlN, and its ternary AlGaN. The AlGaN/GaN heterostructures are grown by molecular beam epitaxy on Si (111) substrate and designed for MEMS applications. Various cantilevers with a width of 10 mu m and lengths going from 100 to 310 mu m were fabricated. The Young's moduli are determined using the resonance frequencies measured by laser Doppler vibrometry (LDV). Finite element modeling (FEM) is used to consider the under-etching of the cantilevers at the anchor. In this study, we find that the Young moduli of GaN and AlN layers are respectively 261 +/- 60 GPa and 339 +/- 78 GPa that compares well with the results found in the literature for bulk materials. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim