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E-mail : natabet@kfupm.sa

High Resolution XPS study of oxide layers grown on Ge substrates using synchrotron radiation. N. Tabet (a), M. Faiz (a), N. M. Hamdan (b) and Z. Hussain (c) (a)Surface Science Laboratory, Physics Department, KFUPM, Saudi Arabia.

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E-mail : natabet@kfupm.sa

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  1. High Resolution XPS study of oxide layers grown on Ge substrates using synchrotron radiation N. Tabet (a), M. Faiz (a), N. M. Hamdan (b) and Z. Hussain (c) (a)Surface Science Laboratory, Physics Department, KFUPM, Saudi Arabia. (b) Physics Department American Univ. of Sharjah, Sharjah UAE. (c) Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, CA 94720. E-mail: natabet@kfupm.edu.sa

  2. Outline 1. Conventional XPS monitoring of the oxide growth 2. High resolution XPS analysis • Native Oxide • Oxide layers obtained by dry oxidation

  3. XPS Monitoring of the Oxide growth Geox 2p Ge0 2p d

  4. ConventionalXPS anal;ysis N. Tabet et al. 2001

  5. XPS at ALS – Berkeley (Synchrotron radiation) Beam line 9.3.2 hn = 300-700 eVEnergy Resolution: E/DE ~ 10000

  6. High Resolution XPS using Synchrotron radiation ALS- Berkeley, 2000

  7. Native oxide on CP4 etched surface Ge 0 Ge 4+ hn = 600eV hn = 300eV

  8. Native oxide on CP4 etched surface Ge 4+ Ge 0 hn = 600eV • Native oxide • After Ar Sputering, 1keV Ar+, PAr=10-5mbar, 50min. • 100min. • 1.5keV, 60min.

  9. Valence Band • Native oxide • After Ar+ Sputtering, 1.5keV, PAr=10-5mbar, 160min. • Then T=315ºC, 20min.

  10. Oxidized Ge(011) surfaceT= 380ºC, t = 25min. PO2 = 400Torrs hn = 300eV 1: As oxidized surface 2-8: After successive Ar+ Sputtering cycles, hn= 650eV. 9: hn= 300eV

  11. Surface Depletion Regionand Core Level Energies Depletion region (~100nm) w Escape depth (~3nm) Incident Photon Ec Fermi Level Eb= Eb (surface) Ev surface Eb(Bulk) Photoelectrons Core level

  12. Oxidized Ge(011) surfaceT= 380ºC, t = 25min. PO2 = 400Torrs Carbides ? 1: As oxidized surface 2-8: After successive Ar+ Sputtering cycles, hn= 650eV.

  13. Conclusion1.High density of Surface States at Ge/GeO2 interface and band bending confirmed2. Lower oxidation state of Ge observed under sputtering.3. Carbides-like XPS signal at the Ge/oxide interface to be investigated Thank you

  14. Study #2 Dopant Segregation at Germanium Surface

  15. EBIC/Grain Boundary SEM EBIC

  16. EBIC/Grain Boundary SEM EBIC

  17. EBIC image of Dopant segregation Surface 50mm Bulk Schottky contact N. Tabet, BIAMS, 2000

  18. Ar etched surface Ge2p3/2 Sb

  19. CP4 etched Ge surface Ge2p3/2 Ge3d

  20. Binding Energy Ge2p3/2 Ge3d

  21. Segregation kinetics

  22. Surface Depletion Regionand Core Level Energies Depletion region (~100nm) w w Escape depth (~3nm) Incident Photon Ec Fermi Level After Sb segregation Eb(Bulk) Ev Photoelectron surface Core level Eb~ Eb (surface) Eb~ Eb (Bulk) w = Nd- 1/2

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