J. Semicond. > 2015, Volume 36?>?Issue 12?> 122003

SEMICONDUCTOR PHYSICS

Correlated barrier hopping of CuO nanoparticles

Jiji Koshy, M. Soosen Samuel, Anoop Chandran and K. C. George

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 Corresponding author: K. C. George, Email: drkcgeorge@gmail.com

DOI: 10.1088/1674-4926/36/12/122003

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Abstract: The ac conduction mechanism in copper oxide nanoparticles with 8 nm size, synthesized by a precipitation method was studied by analyzing ac conductivity in the frequency range of 50 Hz-1 MHz and in the temperature range of 373-573 K. X-ray diffraction and transmission electron microscopy(TEM) were employed for the structural and morphological characterization of CuO nanoparticles. The experimental and theoretical investigations suggested that the ac conduction mechanism in CuO nanoparticles can be successfully explained by a correlated barrier hopping model, which provided reasonable values for the maximum barrier height and characteristic relaxation time. It was also found that bipolaron hopping become prominent up to a particular temperature and beyond that single polaron hopping predominates. Physical parameters such as hopping distance and density of defect states were also calculated. Photoluminescence studies confirm the presence of a surface defect in CuO nanoparticles.

Key words: CuO nanoparticles, correlated barrier hopping, defect states, photoluminescence spectrum, single polaron hopping



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Fig. 1.  (a) TEM image and (b) SAED pattern of CuO nanoparticles.

Fig. 2.  XRD pattern of CuO nanoparticles.

Fig. 3.  PL spectrum of CuO nanoparticles.

Fig. 4.  Variation of total conductivity of CuO nanoparticles as a function of frequency at different temperature.

Fig. 5.  (a) Variation of total conductivity of CuO nanoparticles as a function of temperature at different frequencies. (b) Arrhenius plot for the conductivity of CuO nanoparticles. Variation of ac conductivity of CuO nanoparticles as a function of frequency at different temperatures.

Fig. 6.  Variation of ac conductivity of CuO nanoparticles as a function of frequency at different temperatures.

Fig. 7.  The temperature dependence of the frequency exponent $s$. The solid line is the best fit of s using the CBH model.

Fig. 8.  Theoretical fit for bipolaron hopping of CuO nanoparticles.

Table 1.   Variation of activation energy at different frequencies.

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Table 2.   The variation of defect density in CuO nanoparticles.

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    Received: 10 February 2015 Revised: Online: Published: 01 December 2015

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      Jiji Koshy, M. Soosen Samuel, Anoop Chandran, K. C. George. Correlated barrier hopping of CuO nanoparticles[J]. Journal of Semiconductors, 2015, 36(12): 122003. doi: 10.1088/1674-4926/36/12/122003 ****J Koshy,M S. Samuel, A. Chandran, K. C. George. Correlated barrier hopping of CuO nanoparticles[J]. J. Semicond., 2015, 36(12): 122003. doi:? 10.1088/1674-4926/36/12/122003.
      Citation:
      Jiji Koshy, M. Soosen Samuel, Anoop Chandran, K. C. George. Correlated barrier hopping of CuO nanoparticles[J]. Journal of Semiconductors, 2015, 36(12): 122003. doi: 10.1088/1674-4926/36/12/122003 ****
      J Koshy,M S. Samuel, A. Chandran, K. C. George. Correlated barrier hopping of CuO nanoparticles[J]. J. Semicond., 2015, 36(12): 122003. doi:? 10.1088/1674-4926/36/12/122003.

      Correlated barrier hopping of CuO nanoparticles

      DOI: 10.1088/1674-4926/36/12/122003

      • Department of Physics, S. B. College, Changanassery, Kerala 686101, India

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      • Corresponding author: Email: drkcgeorge@gmail.com
      • Received Date: 2015-02-10
      • Accepted Date: 2015-06-16
      • Published Date: 2015-01-25

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