INFLUENCE OF THE NUCLEATION PROCESS ON THE AZIMUTHAL MISORIENTATION OF HETEROEPITAXIAL DIAMOND FILMS ON SI(001)

In order to clarify the mechanisms that limit the alignment for diamon d heteroepitaxy on Si(001) the influence of different process paramete rs during the bias enhanced nucleation step on the misorientation of d iamond on Si(001) was evaluated using x-ray diffraction texture measur ements, It is shown that the azimuthal width of the {220} pale density maxima in the substrate plane measured in transmission is a quantity that allows a systematic study of the parameter space for oriented nuc leation. From the negligible influence of the substrate surface roughn ess and of the substrate temperature between 675 and 905 degrees C it is concluded that the migration, rotation, and rearrangement processes of nucleated diamond clusters do not control alignment in the tempera ture range studied. In contrast, the duration of the biasing procedure , the process pressure, and the absolute value of the bias voltage can strongly vary the azimuthal distribution between a full width at half -maximum of 3.9 degrees and more than 15 degrees. Low bias voltages fa vor narrow distributions whereas high bias voltages are accompanied by extremely low biasing: times (down to 20 s), When the optimum biasing time is exceeded, the orientation is lost via two different routes. S everal models for the underlying mechanisms are proposed with those th at are most probable pointing to a detrimental influence by ion bombar dment. (C) 1997 American Institute of Physics.