Growth Modes of Ba on Mo(110) Substrate

The growth modes of Ba deposited on a Mo (110) substrate have been investigated by using reflection high-energy electron diffraction (RHEED) and scanning electron microscopy (SEM). In this study, the RHEED specular beam intensity oscillations apparatus is employed to confirm the surface flatness of thin Ba layers on Mo(110) substrate. Ba grows on the Mo(110) substrate via the Stranski-Krastanov growth mode in the temperature range between 300 and 550 °C, in which a monolayer with a (1.5×1.8) structure grows initially, followed by the growth of Ba islands with the (111)Ba plane. Between room temperature (R.T.) and 300 °C, Ba grows on the Mo(110) substrate via the Frank-van der Merwe growth mode, however only several periods of RHEED specular beam intensity oscillations could be observed. Such results suggest that several flat Ba layers grew on Mo(110) substrate via Frank-van der Merwe growth mode and Ba layers have much difficulty in keeping the surface flatness on a Mo(110) substrate. In the temperature range from 300 to 550 °C, only single oscillation was observed, suggesting that the Ba/Mo(110) system adopts the Stranski-Krastanov growth mode at such temperatures with the (1.5×1.8) monolayer.