In situ monitoring of gas source molecular beam epitaxy of silicon with disilane by ultraviolet photoelectron spectroscopy

Ultraviolet photoelectron spectroscopy (UPS) using synchrotron radiation was applied for monitoring in situ gas source molecular beam epitaxy (GSMBE) of silicon with disilane on a Si(OO1)2 X 1 surface. By the in situ UPS observation, information on the hydrogen adsorption state, the hydrogen-free coverage, the work function and the growth rate could be obtained during GSMBE. From the Arrhenius plots of hydrogen-free coverage, work function and growth rate, it turned out that the H,-desorption rate-limited temperature region was divided into two regions. With lowering temperature, we observed that only monohydride remains in the first region and then dihydride appears additionally in the second region. Thus, the break in the H,-desorption rate-limited region is associated with the change in hydrogen adsorption state.