Abstract
We have investigated the microstructure of BxAl1-xN films grown by flow-modulated epitaxy at 1010 oC, with B/(B+Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges x = 0.06 to 0.16, closely following gas-flow ratios. Transmission electron microscopy indicates the sole presence of wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B+Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films.The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at about 9%, for the range of B/(B+Al) gas-flow ratios that we used, which is significantly higher than previously thought.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 334-340 |
| Number of pages | 7 |
| Journal | Journal of Crystal Growth |
| Volume | 475 |
| DOIs | |
| State | Published - Jul 20 2017 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: This work was supported by the U.S. National Science Foundation under DMR-1410874. XHL acknowledges support of the KAUST startup and baseline funding. RDD acknowledges support of the Steve W. Chaddick Endowed Chair in Electro-Optics and the Georgia Research Alliance. The authors acknowledge beneficial discussion of RBS data with Daniel Tseng from Evans Analytical Group, and Dr. Barry Wilkens from Arizona State University. The authors acknowledge the help in EELS from Jing Lu and Dr. Ray Carpenter from Arizona State University.