The Origin of Mis-Oriented Diamond Grains Nucleated Directly on (001) Silicon Surface

The origin of mis-oriented diamond grains frequently observed in heteroepitaxial diamond films on (001) silicon surfaces was studied. By statistically analyzing the in-plane rotation angles of diamond grains in scanning electron microscopy observations, it was found that the distribution of the grain orientation is not random and two satellite distribution peaks at about 20° and 30° accompany the main distribution peak at zero degree referenced to the〈110〉direction of substrate. The interface structure corresponding to the main distribution peak at zero degree of oriented diamond growth has been proposed in our previous studies. In this study, our molecular orbital PM3 simulation of a step-by-step diamond nucleation further reveals two other metastable diamond/silicon interfacial structures. The orientations of the corresponding diamond grains are parallel to the (001) silicon surface but with in-plane rotations of 20° and 30° respectively with respect to the〈110〉direction. We relate these two mis-oriented growths to the two satellite peaks of grain orientation distribution. Based on this study, the possibility in experiment to reduce the formation of mis-oriented configurations and to obtain a perfectly oriented diamond growth is discussed.