The Structure of Interfaces in Oxide Heterojunctions Formed by CVD

Abstract

ABSTRACTWeak-beam imaging is used to characterize the interface structure of hematite (α-Fe2O3)/ sapphire (α-Al2O3) heterojunctions parallel to (0001). The heterojunctions were prepared by lowpressure chemical vapor deposition of hematite directly onto electron-transparent sapphire substrates. Bright-field imaging and selected-area diffraction show that the growth is epitactic. The 5.5% lattice misfit at the interface is found to be accommodated by one of two different hexagonal dislocation networks: (1) b = 1/3<1210> or (2) b = 1/3<1010>. The latter are associated with a “basal twin”-type orientation relationship of the hematite and the alumina.