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 Cheng^1*, 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 GeO_x compared to that of HfO₂/epi-Ge.

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