Epitaxial growth of AlN films via plasma-assisted atomic layer epitaxy
- U.S. Naval Research Laboratory, Washington, DC 20375 (United States)
Thin AlN layers were grown at 200–650 °C by plasma assisted atomic layer epitaxy (PA-ALE) simultaneously on Si(111), sapphire (1120), and GaN/sapphire substrates. The AlN growth on Si(111) is self-limited for trimethyaluminum (TMA) pulse of length > 0.04 s, using a 10 s purge. However, the AlN nucleation on GaN/sapphire is non-uniform and has a bimodal island size distribution for TMA pulse of ≤0.03 s. The growth rate (GR) remains almost constant for T{sub g} between 300 and 400 °C indicating ALE mode at those temperatures. The GR is increased by 20% at T{sub g} = 500 °C. Spectroscopic ellipsometry (SE) measurement shows that the ALE AlN layers grown at T{sub g} ≤ 400 °C have no clear band edge related features, however, the theoretically estimated band gap of 6.2 eV was measured for AlN grown at T{sub g} ≥ 500 °C. X-ray diffraction measurements on 37 nm thick AlN films grown at optimized growth conditions (T{sub g} = 500 °C, 10 s purge, 0.06 s TMA pulse) reveal that the ALE AlN on GaN/sapphire is (0002) oriented with rocking curve full width at the half maximum (FWHM) of 670 arc sec. Epitaxial growth of crystalline AlN layers by PA-ALE at low temperatures broadens application of the material in the technologies that require large area conformal growth at low temperatures with thickness control at the atomic scale.
- OSTI ID:
- 22218132
- Journal Information:
- Applied Physics Letters, Vol. 103, Issue 8; Other Information: (c) 2013 U.S. Government; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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