OBSERVATION OF INVERTED ISLAND-SUBSTRATE STEP STRUCTURES IN HETEROEPITAXIAL GROWTH - GD ON W(100)

Scanning tunneling microscopy has been used to study the growth of Gd on W(100) in which an inverted island-substrate step structure is seen for deposition at elevated temperatures. This results in lower step h eights than would be the case if the islands followed the step morphol ogy, and a reduction of the exposure of high-energy Gd faces. Depositi on at lower temperatures results in flat islands whose size is related to the deposition temperature, with the data supporting a local Stran ski-Krastinov growth mechanism. Low-energy electron diffraction indica tes that the islands are terminated by the Gd(0001) face and that a (8 x2) overlayer is formed. [S0163-1829(97)52140-0].