کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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726903 | 892657 | 2013 | 5 صفحه PDF | دانلود رایگان |
The temperature dependent (30–550 °C) resistivity of zinc oxide (ZnO) has been studied by the standard four probe resistivity method. The room-temperature resistivity of the sample is measured as 0.75 M Ωm. Resistivity versus temperature plot of the sample shows normal NTCR (negative temperature coefficient of resistance) behavior up to 300 °C. However, a crossover from NTCR to a PTCR (positive temperature coefficient of resistance) behavior is observed at ∼300 °C. The origin of the PTCR behavior is explained with the defects present in the ZnO annealed up to 550 °C. Temperature dependent S-parameter (positron annihilation line-shape parameter) indicates the formation of oxygen vacancy like defects in this temperature region. At the PTCR region, the activation energy for the electron conduction is calculated ∼2.6 eV. This value is very close to the theoretically predicted defect level energy of 2.0 eV for oxygen vacancies present in ZnO.
Journal: Materials Science in Semiconductor Processing - Volume 16, Issue 2, April 2013, Pages 332–336