Atomic structure of the Si„113…-„ 3  1 … surface: Charge transfer within tetramers C. C. Hwang Department of Physics, Sung Kyun Kwan University, Suwon 440-746, Korea and Institute of Basic Science, Sung Kyun Kwan University, Suwon 440-746, Korea H. S. Kim, Y. K. Kim, and J. S. Kim Department of Physics, Sung Kyun Kwan University, Suwon 440-746, Korea C. Y. Park Department of Physics, Sung Kyun Kwan University, Suwon 440-746, Korea and Institute of Basic Science, Sung Kyun Kwan University, Suwon 440-746, Korea K. J. Kim, T.-H. Kang, and B. Kim Pohang Accelerator Laboratory, Pohang 790-784, Korea Received 1 October 1998; revised manuscript received 10 March 1999 Atomic structure of the Si(113)3 1 surface was investigated by using synchrotron radiation photoemission spectroscopy. The Si 2 p core-level spectra were measured at surface-sensitive photon energy, 132 eV. From the fitting of the Si 2 p core-level spectrum for the Si(113)3 1 surface, three surface components were resolved at binding energies of about 0.745, -0.554, and 0.34 eV, respectively. The fitting results show that the dimers receive about 0.16 electrons and the rest of tetramers donate about 0.22 electrons on the Si(113)3 1 surface. This strongly supports the fact that the dimers and the rest of the tetramers are relaxed upward and downward, respectively, on Ranke’s model. S0163-18299902424-8 Reconstructions of silicon surfaces have been widely studied until now. It is well known that Si100 and Si111 surfaces are reconstructed to 2 1 and 7 7 surfaces. 1,2 These reconstructions are well understood within the dimer 3 and the dimer-adatom-stacking fault DASRef. 2 models, respectively. From theoretical and experimental studies on low index Si100, Si111 surfaces, the lowering of surface energy is related to several factors; dimers and adatoms tend to be the main building blocks of reconstructed surfaces to reduce dangling-bond density and the surface orbitals have a tendency to be rehybridized from sp 3 toward sp 2 and s 2 p 3 -like configurations, as observed in asymmetric dimers of the Si(100)2 1 surface. 3 As with low-index silicon sur- faces, the bulk-truncated Si113 surfaces in Fig. 1a are also reconstructed to minimize their surface energy. 4–10 Si(113)3 1 Refs. 4–6 or 3 2 Refs. 7–10 reconstruc- tions were reported by using several surface-sensitive tech- niques such as low energy electron diffraction LEED and scanning tunneling microscopy STM. For the Si(113)3 1 surface, several structural models have been suggested, such as Ranke’s ‘‘dimer and adatom’’ model with a symmet- ric or asymmetric dimer, 4 Dabrowski’s model, 9 and the puckering model. 11 However, the detailed atomic structure of the Si(113)3 1 surface is not solved completely. On the other hand, Ranke suggested that rehybridization from sp 3 toward sp 2 and s 2 p 3 -like configurations induced by the sur- face reconstruction may stabilize the structures of the Si113 surface. 4 It seems that several theoretical studies have sug- gested that the rehybridization can occur for the reconstruc- tion of the Si113 surface. 11–14 In the experimental point of view, Hadley et al. gave a similar argument for the Si(113)3 1 surface based on STM results. 6 However, the rehybridized surface atoms could not be resolved clearly in their STM images. It is still unclear whether the Si(113)3 1 surface is rehybridized to stabilize the structure or not. Therefore, we have investigated the detailed atomic structure and the orbital rehybridization on the Si(113)3 1 surface. The experiment was performed in an ultrahigh-vacuum chamber with a base pressure of about 1.410 -9 Pascal at the beam line 2B1 of the Pohang Light Source PLS in Korea. 15 All spectra shown in this paper were obtained using a spherical grating monochrometer and an angle-integrated concentric hemispherical electrostatic analyzer with five channeltrons VSW2A125. The total energy resolution at the photon energy of about 132 eV and the acceptance angle of the spectrometer were about 0.1 eV and 11.4°, respec- tively. The angle between the incident photon beam and the direction of the detected photoelectrons was about 40°. A well-defined n-type Si113 wafer was etched and preoxi- dized chemically according to Shiraki’s method 16 before put- ting it into the chamber. The sample was resistively heated to about 1200 °C several times to make a clean surface. We observed the 3 2 LEED pattern for the clean Si113 sur- face at room temperature RT, in which 2 spots were broader and weaker than those with the 3 1 periodicity. This result is consistent with a previous result. 7 It was ob- served from STM works that the 3 1 exists locally within the large 3 2 surface at RT. 8,9 The 3 2 surface was re- ported to be easily transformed to the 3 1 surface at a sub- strate temperature of about 450 °C. 7 These results indicate that both surfaces have very close surface energy. Similarly, Si(111)5 5 and 7 7 surfaces are known to have close surface energy. As with the formation of the Si(111)5 5 phase upon Si homoepitaxial growth on the Si(111)7 7 PHYSICAL REVIEW B 15 JUNE 1999-I VOLUME 59, NUMBER 23 PRB 59 0163-1829/99/5923/148644/$15.00 14 864 ©1999 The American Physical Society