Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 33: Epitaxie und Wachstum (II)

O 33.7: Vortrag

Donnerstag, 14. März 2002, 17:00–17:15, H44

Growth of ultra thin Ga2O3 film on Ni(100) — •Yanka Jeliazova and René Franchy — Institut für Schichten und Grenzflächen (ISG 3), Forschungszentrum Jülich, D-52425, Germany

The growth of ultra thin films of Ga2O3 on Ni(100) was investigated in the temperature range of 300 – 800 K by using High Resolution Electron Energy Loss Spectroscopy (EELS), Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED), and Scanning Tunneling Microscopy (STM). At 300 K, a 22 Å thick Ga layer was deposited on the Ni(100) surface. Afterwards, the Ga layer was oxidized with oxygen until saturation and an amorphous Ga oxide is formed. The EEL spectrum of the amorphous Ga oxide exhibits an energy loss at  640 cm−1. This loss is assigned to a vibrational excitation of Ga-O bonds in the Ga oxide structure. Annealing up to 700 K and oxidation at this temperature leads to the formation of a well-ordered thin film of Ga2O3. The EEL spectrum of the well-ordered Ga2O3 exhibits the characteristic Fuchs - Kliever phonons of Ga2O3 at 305, 470 and 745 cm−1. The LEED pattern shows a pseudo 12-fold ring structure of two domains with hexagonal structure, which are rotated by 90 with respect to each other. The lattice constant of the hexagonal unit cell of Ga2O3 is determined to be 2.8 Å.

At 300 K, the Ga oxide grows in small islands (clusters) with a size of  30 Å. During annealing between 300 and 800 K coalescence of the Ga2O3 islands takes place. The oxide islands size increases from 30 Å at 300 K to about 300 Å at 700 K. The ordering phenomenon of Ga2O3 was also observed for further oxidation at 700 K.

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