Chemisorption of Ba on deuterium-terminated Si(100) surface

The system of Ba overlayers deposited on a deutetium-terminated Si(100) surface was investigated by means of MDS (metastable de-excitation spectroscopy) and TDS (thermal desorption spectroscopy). Deposition of Ba overlayers caused the reduction of Si-D bond strength because of charge donation to Si substrate from Ba atoms. As a result, about half of preadsorbed D atoms was released from the sample surface at 1 ML Ba deposition. The other half reacted with adsorbed Ba atoms entirely to form Ba-D bonds. Therefore, all the Si-D bonds were lost, which is quite different from the alkali/D/Si(lOO) system. More Ba deposition did not induce the desorption of D atoms. The formed Ba-D bonds are considered to stay between the first and the second layer.