Lattice-matched GaN(0002)/LSAT(111) hetero-structures grown by PLD and analyzed by first-principles calculations

Abstract

La0.3Sr1.7AlTaO6(LSAT), a desired substrate for GaN epitaxial growth with a lattice mismatch as small as 1%, has not been applied in growth of GaN films due to hetero-interface rotation in epitaxial growth. In this paper, high-quality GaN epitaxial films with a small FWHM for GaN(0002) X-ray rocking curve of 0.06° have been grown by pulsed laser deposition (PLD) with a lattice mismatch as small as 1% between GaN and LSAT, and the corresponding mechanism avoiding interface rotation has also been investigated by first-principles calculation. On the one hand, we found that GaN grown on LSAT by PLD shows an in-plane relationship of GaN[2-1-10]//LSAT[1-10], revealing a small lattice mismatch of 1%. On the other hand, the first-principles calculation based on density function theory reveals that GaN growth along GaN[2-1-10]//LSAT[1-10] shows a higher interface energy barrier compared with that along GaN[1-100]//LSAT[1-10] with a lattice mismatch of 12.5%. The high interface energy barrier can only be provided by PLD. Moreover, this work is of paramount importance for understanding the hetero-interface formation mechanism in a GaN/substrates system and will be beneficial to the development of GaN-based devices that require high-quality GaN epitaxial films.