Characterization of chemical bonding features at metal/GeO2 Interfaces by X-ray photoelectron spectroscopy

Matsui, Masafumi; Murakami, Hideki; Fujioka, Toshiyuki; Ohta, Akio; Higashi, Seiichiro; Miyazaki, Seiichi

doi:10.1016/j.mee.2011.03.032

Cited by 21 publications

(13 citation statements)

References 14 publications

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“…9(a) and 11(c), the initial DE Ge on the newly annealed GeO 2 film is plotted as $2.9 eV. This value is almost equal to the result for a thin Ge oxide film obtained by Matsui et al 29 37 is considered to be a key factor. This effect refers to a mechanism that stabilizes (or destabilizes) the core-hole state that is formed upon the ejection of a photoelectron from an emitting atom.…”

Section: B Ap-xps Experimentssupporting

confidence: 54%

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

Mori

Oka

Hosoi

et al. 2016

Journal of Applied Physics

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The energy difference between the oxide and bulk peaks in X-ray photoelectron spectroscopy (XPS) spectra was investigated for both GeO 2 /Ge and SiO 2 /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 GeO 2 on Ge than for thermal SiO 2 on Si above $10 À4 % RH, which is due to the larger amount of water molecules that infiltrate into the GeO 2 film to form hydroxyls. Analyzing the origins of this energy shift, we propose that the positive charging of a partially hydroxylated GeO 2 film, which is unrelated to X-ray irradiation, causes the larger energy shift for GeO 2 /Ge than for SiO 2 /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 GeO 2 film to the Ge bulk, leaving immobile cations or positively charged states in the oxide. This may be related to the reported negative shift of flat band voltages in metaloxide-semiconductor diodes with an air-exposed GeO 2 layer. Published by AIP Publishing.

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Section: B Ap-xps Experimentssupporting

confidence: 54%

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

Mori

Oka

Hosoi

et al. 2016

Journal of Applied Physics

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“…The Ge 3d spectra was deconvulated into Ge 3d 5/2 by considering the spin orbital splitting of Ge 3d core line. The energy splitting of Ge3d is 0.58eV as indicated in previous research [24]. For both samples, the suboxide components were clearly observed at binding energy around 31.5eV.…”

Section: Resultssupporting

confidence: 78%

“…For both samples, the suboxide components were clearly observed at binding energy around 31.5eV. To investigate the Ge 3d 5/2 in detail, the sugnal is deconvulated into six components; Ge 0+ : Gesubstrate, Ge 1~3+ : Ge suboxides, Ge 4+ : GeO 2 , and Ge α+ ) using the same method as described [24]. From the spectral deconvolution of Ge3d 5/2 signal into suboxide components of p-type Ge (100) after air and dry oxygen ambience exposure for 5 hours, we found that the signal due to Ge 1+ on Ge (100) stored in dry oxygen are slightly higher than that of in clean room air.…”

Section: Resultsmentioning

confidence: 99%

Stability of Chlorine Termination on Ge(100) and Ge(111) Surfaces

et al. 2017

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Abstract. The different cleaning solution; HCl and HF solution are used to remove the suboxide and oxide component on Ge surface. The HCl cleaning results chlorine (Cl) termination on Ge surface whereas no Fluorine (F) termination was observed just after HF cleaning. The growth of Ge oxide is studied after treated with HCl cleaning on two surface orientations; (100) and (111), respectively in dry oxygen ambient and cleanroom air by spectroscopic ellipsometry (SE) and x-ray photoelectron spectroscopy (XPS). A clear step and terrace trend was observed for the oxidation growth of Ge (100) and Ge (111) in dry oxygen ambient compared to in clean room air. This trend shows the difference in surface reaction of Ge oxidation as humidity varies. The stability of chlorine termination of Ge (111) than Ge (100) explains the slower growth of oxidation in dry oxygen ambient.

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“…In the spectral deconvolution, the peak shape of the Ge substrate was determined using the reference spectrum of the wet-cleaned Ge substrate, and the chemical shifts of each Ge oxidized state from Ge substrate were used the same values as those described in Ref. 12. The binding energy positions of the Ge 2p 3/2 signals from the Ge substrate and the Al 1s signals from the Al-Al bonding units were summarized as functions of the annealing temperature, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Control of Schottky Barrier Height at Al/p-Ge Junctions by Ultrathin Layer Insertion

et al. 2013

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We have fabricated Al/p-Ge(100) junctions with an ultrathin GeO 2 interfacial control layer and studied the effect of post-metallization annealing in N 2 ambience on the electrical properties from the current-voltage (I-V) characteristics. Then, the changes in the chemical bonding features with annealing were directly evaluated by using hard x-ray photo-emission spectroscopy (HAXPES). Results of these analyses showed that a GeO 2 reduction in the region near the Al/GeO 2 interface occurs after annealing at temperatures over 300 °C and that the Fermi level pinning (FLP) effect increases. This suggests that inserting a thermally and chemically stable thin layer suppresses the FLP effect at the Metal/Ge interface caused by thermal annealing. The release of this FLP effect in Al/p-Ge(100) junctions has also been demonstrated by using ultrathin N 2 sputtered hafnium nitride (HfN x ) layer instead of thermally-grown GeO 2 . And we found that the formation of a nitrogen rich region near the metal/Ge interface was an effective means of controlling the Schottky barrier height.

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Characterization of chemical bonding features at metal/GeO2 Interfaces by X-ray photoelectron spectroscopy

Cited by 21 publications

References 14 publications

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

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

Stability of Chlorine Termination on Ge(100) and Ge(111) Surfaces

Control of Schottky Barrier Height at Al/p-Ge Junctions by Ultrathin Layer Insertion

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