The reaction of monolayers of (metal) absorbâtes with clean (semiconductor) surfaces has long been studied by surface scientists using spectroscopie probes. [1] Recently it has been demonstrated that the knowledge acquired from these studies has led to new techniques for the fabrication of novel epitaxial structures which are not possible by any other means.[2] The orientation of NiSi2, as well as the layer uniformity, was found to be sensitive to slight variations in growth parameters. This discovery has led to the fabrication of single crystal NiSi2 layers of either type A or type B orientation on Si(111).[2] Type A NiSL has the same orientation as the silicon substrate. Type B NiSi2 shares the surface normal <111> axis with the Si, but is rotated 180δ about this axis with respect to the Si. The variation of NiSi2 orientation depends primarily on the deposited nickel thickness and is among the most intriguing phonomena in heteroepitaxial growth. Its significance became even more appreciated when it was discovered that the Schottky barrier height for type A NiSi2 differed significantly from that for type B NiSi2.[3] These results and the prospect of using thin epitaxial suicides in high speed devices have recently attracted a lot of attention as well as triggered investigations of other properties of this material system. Those who followed closely the experimental conditions as described in the original paper[2] have had no trouble in obtaining high quality suicide layers of pure orientation.[4] At the same time, many research groups have used slightly different conditions and, as a result, have not been able to grow single-orientation NiSi2 layers.