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

Authors :
Zoltán Szabó
Zsófia Baji
P. Basa
Hsin Ying Wang
István Bársony
Zsolt Czigány
János Volk
Source :
Applied Surface Science. 379:304-308
Publication Year :
2016
Publisher :
Elsevier BV, 2016.

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.

Details

ISSN :
01694332
Volume :
379
Database :
OpenAIRE
Journal :
Applied Surface Science
Accession number :
edsair.doi...........9d677e8ccaab18f57a1ad88666f81bae
Full Text :
https://doi.org/10.1016/j.apsusc.2016.04.081