Microscopic view of Ge segregation after the growth of the thin Si film and high-κ deposition using in-situ high-resolution synchrotron radiation photoemission
Yi-Ting Cheng1*, Hsien-Wen Wan1, Tun-Wen Pi2, Jueinai Kwo3, Minghwei Hong1
1Graduat Inst. of Applied. Phys. and Dept. of Physics, National Taiwan University, Taipei, Taiwan
2National Synchrotron Radiation Research Center, Hsinchu, Taiwan
3Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
* Presenter:Yi-Ting Cheng, email:d06245005@ntu.edu.tw
We have studied the electronic structure of the thin Si layers grown on epi Ge(001)-2×1 at different substrate temperatures and the subsequent high-κ deposition using high-resolution photoelectron spectroscopy. The Si film of ~ 8 Å was grown in a semiconductor molecular beam epitaxy chamber. The samples were then in-situ transferred to the National Synchrotron Radiation Research Center in Taiwan for photoemission measurements. The epi-Ge surface is composed of buckled dimers on the topmost surface. In the case of room-temperature grown amorphous Si (a-Si) film, the intensity of the Ge up-dimer component from the underlying epi-Ge remains as it is. The Ge down-dimer atoms were partly diffused into the a-Si film, and some of them were segregated to the top of the a-Si surface. The epi-Si grown at 260 - 280°C causes the rest of the Ge down-dimer atoms to move to the epi-Si surface to become both segregated and diffused Ge. The growth of Si merely affects the topmost surface, and the Ge atoms in the second layer of the epi-Ge sustain as it is. The segregated/diffused Ge atoms were oxidized after HfO2 deposition, but the epi-Si has greatly reduced the amount of GeOx compared to that of HfO2/epi-Ge.

Keywords: synchrotron radiation photoelectron spectroscopy, germanium, silicon, segregation , molecular beam epitaxy