Strukture gallia na povrchu Si(111)-(7 x 7): vliv teploty a pokrytí

Gallium structure on the Si(111)-(7 x 7) surface: influence of Ga coverage and temperature

článek v časopise - ostatní, Jost

en

The results of gallium deposition on the Si(111)-(7 x 7) surface at different substrate temperatures (-183, RT, 300, 490 and 530 C) as well as the influence of subsequent annealing of the prepared layers are presented. The gallium structure was monitored by low-energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SR-PES). A detailed analysis of photoelectron spectra was carried out and three different Ga 3d peak components recognized.the first one was related to the (R3xR3) R30 reconstruction, the second to gallium island bases, and the third one to metallic gallium deposited on these bases. Depending on substrate temperature either only the island bases were formed (over 490 C) or these bases were covered with extra gallium atoms in an additional layer (300 C). In the case of room (low) temperature deposition only a weak interaction of gallium with the (7x7) substrate and a non-ordered growth were found. If the gallium coverage exceeded a critical value the gallium formed small droplets on the silicon surface. Annealing of the deposited layers showed differences between the second and the third gallium layer. In addition to previously reported structures a new (3R3x3r3) R30 reconstruction was observed after high temperature deposition followed by annealing to 530 C. This structure was stable in a narrow temperature range and forms an ntermediate step between the (R3 x R3) R30 reconstruction and the island structure.

Práce se zabývá vlivem teploty depozice a žíhání na strukturu gallia na povrchu Si(111)-(7 x 7) pomocí difrakce nízkoenergiových elektronů a fotoelektronové spektroskopie využívající synchrotronové záření. Při depozici za zvýšené teploty vznikají buď pouze základny ostrůvků (nad 490 C) nebo na těchto základnách dochází k růstu další vrstvy (300 C). Při teplotách do 20 C gallium interaguje velmi slabě s rekonstruovaným substrátem (7x7) a dochází k růstu neuspořádaných ostrůvků. Dále byla popsána nová rekonstrukce (3R3x3R3) R30 vznikající při žíhání vrstvy deponované za zvýšené teploty. Tato rekonstrukce je stabilní v úzkém rozsahu teplot a tvoří přechodnou strukturu mezi rekonstrukcí (R3 x R3) R30 a ostrůvky

The results of gallium deposition on the Si(111)-(7 x 7) surface at different substrate temperatures (-183, RT, 300, 490 and 530 C) as well as the influence of subsequent annealing of the prepared layers are presented. The gallium structure was monitored by low-energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SR-PES). A detailed analysis of photoelectron spectra was carried out and three different Ga 3d peak components recognized.the first one was related to the (R3xR3) R30 reconstruction, the second to gallium island bases, and the third one to metallic gallium deposited on these bases. Depending on substrate temperature either only the island bases were formed (over 490 C) or these bases were covered with extra gallium atoms in an additional layer (300 C). In the case of room (low) temperature deposition only a weak interaction of gallium with the (7x7) substrate and a non-ordered growth were found. If the gallium coverage exceeded a critical value the gallium formed small droplets on the silicon surface. Annealing of the deposited layers showed differences between the second and the third gallium layer. In addition to previously reported structures a new (3R3x3r3) R30 reconstruction was observed after high temperature deposition followed by annealing to 530 C. This structure was stable in a narrow temperature range and forms an ntermediate step between the (R3 x R3) R30 reconstruction and the island structure.

Gallium, Ga, Silicon, Si(100), Water, Surface structure, Low energy electron diffraction (LEED), Synchrotron radiation photoelectron spectroscopy

2007

10.01.2007

0953-8984

19

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