Growth of MgO thin films on M-, A-, C- and R-plane sapphire by laser ablation

Epitaxial MgO thin films have been grown on single crystal substrates of M- plane (10 (1) over bar 0), A-plane ((1) over bar (1) over bar 20), C-plane (0001) and R-plane (1 (1) over bar 02) sapphire by laser ablation of a Mg m etal target in a molecular oxygen atmosphere using 1064 nm radiation from a Nd:YAG laser. X-ray measurements indicate that the MgO grows epitaxially; on all substrates, with its orientation dependent on the cut of the sapphir e substrate. (110)-oriented MgO grows on M-plane sapphire, while (111)-orie nted MgO films are found on both the A-plane and the C-plane sapphire. The orientation of MgO found on R-plane sapphire appears to be surface and temp erature dependent. The principal growth orientation obtained on the R-plane is (100)-oriented MgO although (100) growth tilted 30 degrees from the [1 (1) over bar 1] Al2O3 direction can result. X-ray area mapping has been per formed to determine the mosaicity, d value spread and strain present in the films. These data are compared with the in-plane orientation and the misma tch of the MgO and Al2O3 lattices in an attempt to relate the preferred ori entation to the plane of the sapphire on which it is grown.