Defects in semipolar (11(2)over-bar(2)over-bar) ZnO grown on (112) LaAlO3/(La, Sr) (Al, Ta)O-3 substrate by pulsed laser deposition

Abstract

The microstructure of semipolar (11 (2) over bar(2) over bar) ZnO deposited on (112) LaAlO3/(La, Sr) (Al, Ta)O-3 was investigated by transmission electron microscopy. The ZnO shows an in-plane epitaxial relationship of [11 (2) over bar3](ZnO) parallel to [11 (1) over bar](LAO/LSAT) with oxygen-face sense polarity. The misfit strain along [11 (2) over bar3](ZnO) and [1 (1) over bar 00](ZnO) is relieved through the formation of misfit dislocations with the Burgers vectors b = 1/6[11 (2) over bar3](ZnO) and b = 1/3 < 1 (2) over bar 10 >(ZnO), respectively. The line defects in the semipolar ZnO are predominantly perfect dislocations, and the dislocation density decreases with increasing ZnO thickness as a result of dislocation reactions. Planar defects were observed to lie in the M-plane and extend along < 0001 >, whereas basal stacking faults were rarely found.