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ERDA, for measurement of hydrogen in PV applications

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Really what is ERD fancy RBS. Measurement of backscattered particle energy. ... Example of an ideal RBS spectrum: Generalised two part dielectric on a substrate. ... – PowerPoint PPT presentation

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Title: ERDA, for measurement of hydrogen in PV applications


1
  • ERDA, for measurement of hydrogen in PV
    applications
  • -- DERF 06/08 --
  • Presented by Andrew Thomson
  • Supervisor Dr Keith McIntosh

2
Introduction
  • Specialised form of ion beam analysis.
  • Understand the role of H in passivation.
  • Measuring SC dielectric coatings and
    silicondielectric interfaces, after various
    treatments.
  • Overview

3
Really what is ERD fancy RBS
  • Measurement of backscattered particle energy.
  • Gives energy count and yield.
  • Knowing R cross-sections give quantative
    measurement.

4
Generalised ERD setup
  • Forward scatter measured.
  • Incident ion suppressed.
  • Experimental cross-sections.
  • RBS and ERD combined.
  • Generally energy only is measured.

5
Resolution limits
  • Detection limits
  • For an optimised sample 20 ppm, up to 1000nm
    depth.
  • Comparative techniques
  • SIMS, similar resolution, better depth
    resolution.
  • FTIR, measures bonds, unsure of resolution.

6
The physics of ERD descriptively
  • Single atomic layer
  • Multiple layers add spread
  • Increased variance.
  • Straggle lowers energy.
  • Measured spectrum convolution of input spectrum
    with straggling function.

7
The physics of ERD descriptively
  • Example of an ideal RBS spectrum
  • Generalised two part dielectric on a substrate.
  • Example of an actual silicon substrate.

8
Setup at ANSTO Lucas Heights

9
Setup at ANSTO Lucas Heights
  • 3 MeV tandem accelerator with a He ion source
  • So far we have used an incident power of 1.8 MeV.
  • Mylar foil
  • RBS
  • T 170 , ß 60 , a 70 .
  • ERD
  • T 30 , ß 80 , a 70 .

10
RBS and ERD measurements
  • RB Spectra of a TiO2 dielectric layer on.
  • ERD specra
  • Shows surface absorption of H

11
Modelling Spectrums
  • Guess work
  • Layers.
  • Energy per channel.
  • Incident flux.
  • Substrate.
  • Experience needed

12
Modelling Spectrums RBS TiO2
13
Modelling Spectrums ERD TiO2
14
PECVD vs. TiO2
  • PECVD
  • Optimised TiO2

15
Plans for PV applications of ERDA
  • Hydrogen characterisation
  • Basic PV processing steps.
  • PV dielectrics.
  • Hydrogenated TiO2
  • Degradation processes.
  • Other applications
  • Boron, and phos profiles.
  • Densification of TiO2.
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