Comparative study of GeO2/Ge and SiO2/Si structures on anomalous charging of oxide films upon water adsorption revealed by ambient-pressure X-ray photoelectron spectroscopy
- Osaka Univ. (Japan). Graduate School of Engineering. Dept. of Precision Science and Technology
- Osaka Univ. (Japan). Graduate School of Engineering. Dept. of Material and Life Science
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source
The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated in this paper for both GeO2/Ge and SiO2/Si structures with thickness-controlled water films. This was achieved by obtaining XPS spectra at various values of relative humidity (RH) of up to ~15%. The increase in the energy shift is more significant for thermal GeO2 on Ge than for thermal SiO2 on Si above ~10-4% RH, which is due to the larger amount of water molecules that infiltrate into the GeO2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO2/Ge than for SiO2/Si. A possible microscopic mechanism of this intrinsic positive charging is the emission of electrons from adsorbed water species in the suboxide layer of the GeO2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. Finally, this may be related to the reported negative shift of flat band voltages in metal-oxide-semiconductor diodes with an air-exposed GeO2 layer.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); Japan Society for the Promotion of Science (JSPS) (Japan); Murata Science Foundation (Japan); Mikiya Science and Technology Foundation (Japan)
- Grant/Contract Number:
- AC02-05CH11231; JP24686020; JP26630026; JP16K14133
- OSTI ID:
- 1377479
- Journal Information:
- Journal of Applied Physics, Vol. 120, Issue 9; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
GeO 2 Encapsulated Ge Nanostructure with Enhanced Lithium-Storage Properties
|
journal | January 2019 |
Similar Records
Optical and structural properties of SiO{sub x} films grown by molecular beam deposition: Effect of the Si concentration and annealing temperature
GeO{sub 2}-doped SiO{sub 2} sputtered thin films: Microstructure, stoichiometry, and optical properties