| AVS 56th International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS1-MoM |
| Session: | Vibrational Spectroscopy and Surface Reactions |
| Presenter: | I.S. Chopra, The University of Texas at Dallas |
| Authors: | I.S. Chopra, The University of Texas at Dallas J.-F. Veyan, The University of Texas at Dallas M.P. Nadesalingam, The University of Texas at Dallas N. Dao, The University of Texas at Dallas O. Seitz, The University of Texas at Dallas W.P. Kirk, The University of Texas at Dallas J. Randall, Zyvex Labs M. Huang, The University of Texas at Dallas K. Cho, The University of Texas at Dallas R.M. Wallace, The University of Texas at Dallas Y. Chabal, The University of Texas at Dallas |
| Correspondent: | Click to Email |
Atomic layer epitaxy (ALE) is a critical step in trying to achieve Atomically Precise Manufacturing (APM) of new devices such as quantum dots, qubits, NEMS oscillators and biomedical devices. Here we report the ALE of Si using molecular disilane on (2x1)-Si(100) surface. The surfaces have been characterized using Fourier transform infrared spectroscopy (FTIR), angle resolved x-ray photoelectron spectroscopy (ARXPS), low energy electron diffraction (LEED) and quadrupole mass spectrometry (QMS).
IR absorption measurements have been performed in transmission mode (70o incidence). Clean Si(100)x(2x1) samples are prepared by controlled thermal desorption of chemically oxidized Si wafers. On clean (2x1) – Si(100) surfaces, saturation doses of the order of 10L are observed, which is considerably lower than data reported earlier (3000L)1. At saturation coverage absorption bands in the ~2100 cm-1 range (and also ~950 and 650 cm-1) indicate that monohydrides (SiH), dihydrides (SiH2) and trihydrides are formed, consistent with shifts of the Si2p core level using angle resolved X-ray photoelectron spectroscopy. The relative intensities of these bands have been studied as a function of exposure and substrate temperature, and present differences from earlier room temperature measurements.2 The observation of trihydrides indicates that one product from disilane decomposition is the silyl group, although its concentration depends on exposure and temperature. The thermal stability of these resulting surfaces has been examined with infrared absorption, temperature-programmed desorption (TPD) and LEED. We have also examined the effects of He ion surface de-passivation.3
To gain a fundamental understanding on surface reaction mechanisms, we have performed a density functional theory (DFT) study on the reactions of monohydrides (SiH), dihydrides (SiH2), trihydrides and disilane on both clean and hydrogen passivated Si(100)-(2x1) surfaces. The calculated atomic configurations, electronic structures, and vibration frequencies are compared with the experimental data.References
1 Yoshiyuki Suda, Naoyuki Hosoya and Kazushi Miki, Appl. Surf. Sci. 216, 424-430 (2003).
2 Masanori Shinohara, Michio Niwano, Yoichiro Neo and Kuniyoshi Yokoo, Thin. Solid Films 309, 16-20 (2000).
3 This material is based upon work supported by the Defense Advanced Research Project Agency (DARPA) and Space and Naval Warfare Center, San Diego (SPAWARSYSCEN-SD) under contract N66001-08-C-2040. It is also supported by a grant from the Emerging Technology Fund of the State of Texas to the Atomically Precise Manufacturing Consortium.