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Influence of substrate temperature and oxygen/argon flow ratio on the electrical and optical properties of Ga‐doped ZnO thin films prepared by rf magnetron sputtering
Author(s) -
Kim Sookjoo,
Jeon Jinho,
Kim Hyoun Woo,
Lee Jae Gab,
Lee Chongmu
Publication year - 2006
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200610748
Subject(s) - crystallinity , materials science , electrical resistivity and conductivity , substrate (aquarium) , thin film , sputter deposition , analytical chemistry (journal) , doping , gallium , sputtering , optoelectronics , composite material , nanotechnology , chemistry , metallurgy , oceanography , chromatography , geology , electrical engineering , engineering
Effects of substrate temperature and atmosphere on the electrical and optical properties of Ga‐doped ZnO thin films deposited by rf magnetron sputtering were investigated. The electrical resistivity of Ga‐doped ZnO (GZO) films decreases as the substrate temperature increases from room temperature to 300°C. A minimum resistivity of 3.3 × 10 –4 Ω cm is obtained at 300°C and then the resistivity increases with a further increase in the substrate temperature to 400°C. This change in resistivity with the substrate temperature is related to the crystallinity of the GZO film. The resistivity nearly does not change with the O 2 /Ar flow ratio, R for R < 0.25 but increases rapidly with R for R > 0.25. This change in resistivity with R is also related to crystallinity. The crystallinity is enhanced as R increases, but if the oxygen partial pressure is higher than a certain level (R = 0.25 ± 0.10) gallium oxides precipitate at grain boundaries, which decrease both carrier concentration and mobility. Optical transmittance increases as R increases for R < 0.75. This change in transmittance with R is related to changes in oxygen vacancy concentration and surface roughness with R. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)