Fabrication of coherent γ-Al2O3/Ga2O3 superlattices on MgAl2O4 substrates

We succeeded in fabricating 10-period coherent gamma-Al2O3/Ga2O3 superlattices (SLs) on MgAl2O4 substrates by molecular beam epitaxy. By varying each layer thickness, we tuned the average Al composition (x(ave)) of the coherent SLs from 0.20 to 0.85, and obtained nearly-lattice-matched SLs to the substrate at x(ave) similar to 0.5. The lattice-matched SLs maintained coherent interfaces up to a period length of 7.2 nm in spite of a large lattice mismatch between the end members. Our results suggest lots of flexibility in designing gamma-(Al(x)Ga(1-)x)(2)O-3-based heterostructures for future functional heterojunction devices. (C) 2019 The Japan Society of Applied Physics