Crystalline Si3N4 thin films on Si(111) and the 4x4 reconstruction on Si3N4(0001)

Crystalline silicon nitride (Si3N4) thin films have been grown on Si(111) surfaces by exposing the substrate to NH3 at a temperature of greater than or equal to 1075 K. An "8 x 8" electron diffraction pattern was observable even for a relatively thick Si3N4 film. Images of the same surfaces obtained with a scanning tunneling microscope show surface superstructure with a period of 30.7 Angstrom, and a minimum step height of 2.9 Angstrom. These suggest the formation of beta-Si3N4, with Si3N4(0001)parallel to Si(111). The 30.7-Angstrom periodic superstructure is attributed to the 4 x 4 surface reconstruction on Si3N4(0001). [S0163-1829(99)50428-1].