La-silicate of (La2O3)0.6(SiO 2)0.4 was prepared by e-beam evaporation of mixed oxides target to control the chemical bonding state and band structure of La 2O3 film on n-GaAs (001). Prior to deposition of La-silicate film, sulfur passivation was performed on the surface of GaAs. The composition and uniformity of La-silicate film were simulated from the ratio of photoelectron intensity, ILa 4d/ISi 2p, using angle resolved X-ray photoelectron spectroscopy. The formation of hydroxide phase was effectively prohibited when La-silicate is formed. Energy band gap of La 2O3 and La-silicate were estimated as ∼ 5.6 eV and ∼ 6.5 eV, respectively, by combining valence band and absorption spectra. The change in the energy band structure with regard to n-GaAs was correlated with electrical properties. An enhanced conduction band offset of La-silicate is evidenced by Fowler-Nordheim tunneling mechanism.
Bibliographical noteFunding Information:
This work was supported by Korea Research Foundation Grant (KRF-2004-041-D00431). The experiments at PLS were supported in part by MOST and POSTECH.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry