TEM analysis of nanometer-size surface structures formed by bias enhanced nucleation of diamond on iridium

Bias enhanced nucleation of diamond on Ir/SrTiO3(0 0 1) substrates usually causes a characteristic roughening of the Ir surface. On top of this, small particles with typical dimensions between 5 and 10 nm are found. Different microscopy techniques (atomic force microscopy, scanning electron microscopy, and transmission electron microscopy) were used in order to study the structure of these particles and determine their role in the diamond nucleation process. The nanoparticles are found laying loosely on the Ir surface: either equally dispersed or in clusters. After an additional short growth step, they can also be observed on top of the diamond grains. High-resolution transmission electron microscopy micrographs reveal a lattice constant that is close to that of Ir. Similar particles were observed on the nucleation side of thick delaminated diamond films after a growth process of several days. In contrast to the findings on top of the Ir surface, these nanoparticles are sometimes well aligned to the diamond film and show a wide distribution of lattice spacing. All results of the present study concurrently question any crucial role of the nanoparticles in the diamond nucleation process on iridium. (C) 2002 Elsevier Science B.V. All rights reserved.