MOLECULAR-BEAM EPITAXIAL-GROWTH OF ALN SINGLE-CRYSTALLINE FILMS ON SI(111) USING RADIOFREQUENCY PLASMA-ASSISTED NITROGEN RADICAL SOURCE

We have grown AlN films on Si (111) using a molecular beam epitaxy (MB E) approach in which reactive nitrogen species are generated in a remo te 13.56 MHz radio-frequency plasma discharge, nitrogen radical source . Effects of the Al/Si (111) gamma-phase on epitaxial growth of AlN on Si (111) has been studied. Successive processes of forming stable Al/ Si (111) gamma-phase at 800 degrees C followed by MBE growth without i nterrupting Al beam exposure was effective to prevent amorphous SiNx f ormation on Si substrate. The Al/Si (111) gamma-phase was found effect ive to fix the orientation relationship between AlN and Si for epitaxi al growth of single crystal AlN. Single crystal AlN was grown on the A l/Si (111) gamma-phase at the temperature as low as 400 degrees C. By optimizing growth conditions (substrate temperature, V/III ratio and p lasma conditions), growth of single crystal AlN films in a quasi-layer -by-layer fashion was observed for the thickness up to 60 nm. The opti mized value on the growth temperature was 800 degrees C and that on th e V/III ratio was 440. The surface of the ALN film grown under the opt imized condition was quite smooth with a root mean square roughness of 0.3 nm. The resistivity of the film was about 2 x 10(9) Omega cm. (C) 1998 American Vacuum Society. [S0734-2101(98)11104-1].