Photoanodic oxidation of InP in acid solution and its surface chemistry: On the interplay of photons, protons and hydrodynamics

Dennis H. van Dorp, Genis Vanheusden, Kris Paulussen, Ibrahim Hassan, Simon Van Wonterghem, Graniel H. Abrenica, Praveen Dara, Johan Meersschaut, Thierry Conard, Frank Holsteyns, John J. Kelly

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Factors determining etching and passivation of n-type InP in H2SO4 and HCl solution and the corresponding surface chemistry are considered. Passivation is favoured by higher light intensity and lower proton and Cl− ion concentration. Ex-situ surface analysis shows the passive (bi)layer to consist mainly of oxide-based In3+ and P5+ components: InPO4 and In(PO3)3. Hydrodynamics is found to play a decisive and surprizing role in determining the kinetics of the surface reactions. Oxygen-bridge formation between surface In and P atoms, as a result of deprotonation of a P-OH reaction intermediate, is considered to be important in determining competition between the two reaction paths: etching and passivation. These results are compared with markedly contrasting results for n-type GaAs under similar experimental conditions.
Original languageEnglish
Article number136872
Number of pages13
JournalElectrochimica Acta
Volume360
DOIs
Publication statusPublished - 10 Nov 2020

Keywords

  • Anodic oxidation
  • GaAs
  • InP
  • Native oxide
  • Passivation
  • Surface chemistry

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