GROWTH OF TE THIN-FILMS DEPOSITED AT ROOM-TEMPERATURE ON THE SI(100)2X1 SURFACE

The electronic properties and the growth mode of very thin films of tellurium deposited in ultra-high vacuum, at room temperature, on the Si(100)2 x 1 surface have been studied by means of XPS, AES and LEED spectroscopy. Additionally the measured AES weighted peak to peak intensity ratio between Te and Si was compared with calculated layer by layer and Stransky-Krastanov growth mode curves. Our results indicate that the interaction between tellurium and silicon is very weak like the characteristic behaviour of simple metals near Si in the Periodic Table. Tellurium grows on large 1 x 1 domains reconstructed on Si(100)2 x 1 until a layer is completed, at approximate to 2 Angstrom of nominal coverage. Once the substrate is completely covered by the first Te layer, and up to approximate to 10 Angstrom, the deposited tellurium grows, forming islands which have a 1 x I order on Si(100), and covers approximate to 40% of the underlying continuous layer. With increasing thickness the islands begin to coalesce and the Te atoms do not follow the lattice order of the Si(100) substrate any more. The behaviour of Te on Si(100) is found to be very similar to that of antimony because of the similar electronic core level structure and atomic radius. However, the higher mobility of Te atoms with respect to Sb atoms allows the formation of a continuous layer of Te on Si(100)2 x 1 also at room temperature, whereas Sb needs higher temperatures. The observed weak absorbate-substrate interaction, together with a strong adsorbate-adsorbate interaction, leads to the saturation of the dangling bonds of the silicon substrate, which shows a bulk-like behaviour, and are responsible for the growth mode of the tellurium deposited on Si(100)2 x 1.