Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5425901 | Surface Science | 2006 | 6 Pages |
We have studied the room-temperature growth of Cr on Ir(1 1 1) by scanning tunneling microscopy. Even in the low-coverage regime, up to a total coverage of 2 monolayers (ML), Cr does not grow in the layer-by-layer mode. Instead, we observe islands with local coverages Î between 1 ML and 5 ML. While the 1st layer growth is pseudomorphic, sporadic defect lines are observed in the 2nd layer. For Π⩾ 3 ML periodic one-dimensional dislocation lines appear indicating the onset of strain relief. Scanning tunneling spectroscopy reveals that islands with Π= 1 ML exist in two modifications. Though their tunneling spectra are qualitatively rather similar, direct comparison shows that the main peak is shifted by about 15 mV, resulting in peak positions of â0.255 V and â0.270 V. We interpret these two modifications as regular fcc Cr and Cr which exhibits a faulted hcp stacking on Ir(1 1 1), respectively. The assignment of fcc to areas directly attached to substrate steps together with the evolution of the ratio of the different ML-areas with coverage leads to the conclusion that hcp is the more favorable stacking.