Homogeneous transparent conductive ZnO: Ga by ALD for large LED wafers

Zoltán Szabó, Zsófia Baji, Péter Basa, Z. Czigány, I. Bársony, Hsin Ying Wang, János Volk

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Highly conductive and uniform Ga doped ZnO (GZO) films were prepared by atomic layer deposition (ALD) as transparent conductive layers for InGaN/GaN LEDs. The optimal Ga doping concentration was found to be 3 at%. Even for 4" wafers, the TCO layer shows excellent homogeneity of film resistivity (0.8 %) according to Eddy current and spectroscopic ellipsometry mapping. This makes ALD a favourable technique over concurrent methods like MBE and PLD where the up-scaling is problematic. In agreement with previous studies, it was found that by an annealing treatment the quality of the GZO/p-GaN interface can be improved, although it causes the degradation of TCO conductivity. Therefore, a two-step ALD deposition technique was proposed and demonstrated: a "buffer layer" deposited and annealed first was followed by a second deposition step to maintain the high conductivity of the top layer.

Original languageEnglish
Pages (from-to)304-308
Number of pages5
JournalApplied Surface Science
Volume379
DOIs
Publication statusPublished - Aug 30 2016

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Keywords

  • Atomic layer deposition
  • GZO
  • LED
  • Rapid thermal annealing
  • TCO

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

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