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Title: Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs

Abstract

In this study, changes in surface Fermi-level of Si and GaAs, caused by doping and cleaning, are investigated by Auger electron spectroscopy. Based on the Auger voltage contrast, we compared the Auger transition peak energy but with higher accuracy by using a more accurate analyzer and an improved peak position determination method. For silicon, a peak shift as large as 0.46 eV was detected when comparing a cleaned p-type and n-type wafer, which corresponds rather well with the theoretical difference in Fermi-levels. If no cleaning was applied, the peak position did not differ significantly for both wafer types, indicating Fermi-level pinning in the band gap. For GaAs, peak shifts were detected after cleaning with HF and (NH 4) 2S-solutions in an inert atmosphere (N 2-gas). Although the (NH 4) 2S-cleaning in N 2 is very efficient in removing the oxygen from the surface, the observed Ga- and As-peak shifts are smaller than those obtained after the HF-cleaning. It is shown that the magnitude of the shift is related to the surface composition. After Si-deposition on the (NH 4) 2S-cleaned surface, the Fermi-level shifts back to a similar position as observed for an as-received wafer, indicating that this combination is notmore » successful in unpinning the Fermi-level of GaAs.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [4];  [1];  [1]
  1. KU Leuven, Heverlee (Belgium)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. IBM Research Zurich, Ruschlikon (Switzerland)
  4. KU Leuven, Heverlee (Belgium); IMEC vzw, Heverlee (Belgium)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1418021
Report Number(s):
PNNL-SA-130366
Journal ID: ISSN 0169-4332; PII: S0169433218300801
Grant/Contract Number:
AC05-76RL01830
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Applied Surface Science
Additional Journal Information:
Journal Name: Applied Surface Science; Journal ID: ISSN 0169-4332
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Auger electron spectroscopy; semiconductor surface; Fermi level shifts; surface cleaning

Citation Formats

Debehets, J., Homm, P., Menghini, M., Chambers, S. A., Marchiori, C., Heyns, M., Locquet, J. P., and Seo, J. W. Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs. United States: N. p., 2018. Web. doi:10.1016/J.APSUSC.2018.01.079.
Debehets, J., Homm, P., Menghini, M., Chambers, S. A., Marchiori, C., Heyns, M., Locquet, J. P., & Seo, J. W. Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs. United States. doi:10.1016/J.APSUSC.2018.01.079.
Debehets, J., Homm, P., Menghini, M., Chambers, S. A., Marchiori, C., Heyns, M., Locquet, J. P., and Seo, J. W. 2018. "Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs". United States. doi:10.1016/J.APSUSC.2018.01.079.
@article{osti_1418021,
title = {Detecting Fermi-level shifts by Auger electron spectroscopy in Si and GaAs},
author = {Debehets, J. and Homm, P. and Menghini, M. and Chambers, S. A. and Marchiori, C. and Heyns, M. and Locquet, J. P. and Seo, J. W.},
abstractNote = {In this study, changes in surface Fermi-level of Si and GaAs, caused by doping and cleaning, are investigated by Auger electron spectroscopy. Based on the Auger voltage contrast, we compared the Auger transition peak energy but with higher accuracy by using a more accurate analyzer and an improved peak position determination method. For silicon, a peak shift as large as 0.46 eV was detected when comparing a cleaned p-type and n-type wafer, which corresponds rather well with the theoretical difference in Fermi-levels. If no cleaning was applied, the peak position did not differ significantly for both wafer types, indicating Fermi-level pinning in the band gap. For GaAs, peak shifts were detected after cleaning with HF and (NH4)2S-solutions in an inert atmosphere (N2-gas). Although the (NH4)2S-cleaning in N2 is very efficient in removing the oxygen from the surface, the observed Ga- and As-peak shifts are smaller than those obtained after the HF-cleaning. It is shown that the magnitude of the shift is related to the surface composition. After Si-deposition on the (NH4)2S-cleaned surface, the Fermi-level shifts back to a similar position as observed for an as-received wafer, indicating that this combination is not successful in unpinning the Fermi-level of GaAs.},
doi = {10.1016/J.APSUSC.2018.01.079},
journal = {Applied Surface Science},
number = ,
volume = ,
place = {United States},
year = 2018,
month = 1
}

Journal Article:
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  • Work function, photoemission yield, and Auger electron spectra were measured on (001) p-type GaAs during negative electron affinity (NEA) surface preparation, surface degradation, and heating processes. The emission current sensitively depends on work function change and its dependence allows us to determine that the shape of the vacuum barrier was close to double triangular. Regarding the NEA surface degradation during photoemission, we discuss the importance of residual gas components the oxygen and hydrogen. We also found that gentle annealing (≤100 °C) of aged photocathodes results in a lower work function and may offer a patch to reverse the performance degradation.
  • Au-interfacial oxide layer (GeO/sub 2/, Sb/sub 2/O/sub 3/, Bi/sub 2/O/sub 3/, SnO/sub 2/ and native oxide mixture of AS/sub 2/O/sub 3/ and Ga/sub 2/O/sub 3/)-semiconductor (GaAs) structures were investigated by the Auger Electron Spectroscopy Method. The results of depth profiling with Ar/sup +/-ion sputtering are presented for all metal-insulator-semiconductor (MIS) structures. ''Metal'' atoms from deposited interfacial oxide layers (Ge from Ge/sub 2/O/sub 3/, Sb from Sb/sub 2/O/sub 3/, Bi from Bi/sub 2/O/sub 3/, and Sn from SnO/sub 2/) were observed on the surface. Only As atoms were observed for the native oxide mixture of As/sub 2/O/sub 3/ and Ga/sub 2/O/submore » 3/ interfacial layer. These findings suggest that As/sub 2/O/sub 3/ is the dominating oxide at the metal-oxide interface for native oxide GaAs MIS solar cells. The interfacial reaction takes place between Au and the interfacial layer at room temperature. The ''diffusion'' of metal atoms from the interfacial layer towards the surface is suspected to play a role in degradation effect in GaAs MIS solar cells.« less
  • The use of Auger electron spectroscopy (AES) combined with in situ sputter etching for revealing the metallurgy of the metal-semiconductor interface is presented. The physical basis, measurement techniques, and data interpretation for Auger analysis of thin-film structures are briefly reviewed. Results of a detailed study of an alloyed multilayered contact (Ni/Au-Ge) on n-type epitaxial GaAs are summarized to illustrate how electrical and metallurgical contact properties can be correlated using AES. In addition, the results of a study of the growth kinetics and chemical phase identification of palladium silicide on single-crystal Si is given, as well as the initial results ofmore » a study of aluminum-palladium silicide interaction at elevated temperature. (auth)« less
  • Electrical and deep level transient spectroscopy measurements on Schottky barriers were performed in order to characterize electrically active defects in n-type GaAs (Bridgman substrates or liquid-phase epitaxial layers) after pulsed electron beam annealing. Both surface damage and bulk defects were observed in the Bridgman substrates depending on the pulse energy density. No electron traps were detected in the liquid-phase epitaxial layers before and after annealing for an energy density of 0.4 J/cm/sup 2/. The existence of an interfacial insulating layer at the metal-semiconductor interface, associated with As out-diffusion during the pulsed electron irradiation, was revealed by the abnormally high valuesmore » of the Schottky barrier diffusion potential. Moreover, two new electron traps with activation energy of 0.35 and 0.43 eV, called EP1 and EP2, were introduced in the Bridgman substrates after pulsed electron beam annealing. The presence of these traps, related to the As evaporation, was tentatively attributed to the decrease of the EL2 electron trap signal after 0.4-J/cm/sup 2/ annealing. It is proposed that these new defects states are due to the decomposition of the As/sub Ga/-As/sub i/ complex recently considered as the most probable defect configuration for the dominant EL2 electron trap usually detected in as-grown GaAs substrates.« less