High-Mobility Single-Crystalline WO3 Epiaxial Films Grown on LSAT Substrates

Abstract

MBE growth of WO3 on (100) LSAT substrates is reported. It is revealed that the initial WO3 layer crystallizes in the cubic WO3 structure although the lattice constant in the growth direction is shrunken due to the coherent growth. This cubic structure is relaxed and becomes close to the orthorhombic WO3 structure with increasing thickness. The electron mobility in a 5 nm thick film was as large as 560 cm²/Vs while it decreased to the typical vale of bulk crystals of about 10 cm²/Vs in the thicker films more than 30 nm.