Modifikationen der Wachstumsmorphologie in der Homoepitaxie auf Pt(111)

The growth morphology after conventional vapor phase deposition in homoepitaxy on Pt(111) and possibilities of its modification - by temperature variation, by simultaneous ion bombardment and by the use of adsorbates - have been investigated by means of temperature variable scanning tunneling microscopy (STM). In order to quantitatively study the growth a new criterion has been introduced - the growth number. It characterizes the actual state of a considered system after growth which has taken place between the limits of the two extremes, i.e. the ideal layer-by-layer growth and the ideal three dimensional growth. The growth number is applied and compared to the output of the normalized interface width criterion for the temperature and coverage dependence of the growth morphology. For conventional vapor phase deposition of Pt on Pt(111) the growth is known to proceed nearly layerwise at low and at high temperatures and three dimensional in the medium temperature range. Application of the growth number uncovers that the system is in intermediate states for most of the deposition temperatures. A binary classification of growth morphologies in layer-by-layer or three dimensional is therefore insufficient to describe the state a growth system is in. The growth number reveals that only around 430 K the system is very close to an ideally threedimensional growth. An almost ideal layer-by-layer growth is only found around 640 K. It is shown that this growth is caused by the Pt(111)-reconstruction which significantly decreases the island size without changing the diffusion of adatoms on top of the islands. Thereby an improved interlayer mass transport is induced. (orig.)123 refs.Available from TIB Hannover: RA 831(3256) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman