Article ID Journal Published Year Pages File Type
1552577 Superlattices and Microstructures 2016 5 Pages PDF
Abstract

•We grew a number of high-purity AlN films by molecular beam epitaxy.•The biaxial stress coefficient for E2(high) mode was determined, well in accord with the theoretical value.•The crystalline quality of MBE-grown AlN films was improved by increasing the Al/N ratio during AlN buffer layer growth.

Residual stress in AlN films grown by molecular beam epitaxy (MBE) has been studied by Raman scattering spectroscopy. A strain-free Raman frequency and a biaxial stress coefficient for E2(high) mode are experimentally determined to be 657.8 ± 0.3 cm−1 and 2.4 ± 0.2 cm−1/GPacm−1/GPa, respectively. By using these parameters, the residual stress of a series of AlN layers grown under different buffer layer conditions has been investigated. The residual compressive stress is found to be obviously decreased by increasing the Al/N beam flux ratio of the buffer layer, indicating the generation of tensile stress due to stronger coalescence of AlN grains, as also confirmed by the in-situ reflection high energy electron diffraction (RHEED) monitoring observation. The stronger coalescence does lead to improved quality of AlN films as expected.

Related Topics
Physical Sciences and Engineering Materials Science Electronic, Optical and Magnetic Materials
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