, Volume 108, Issue 4, pp 921-928
Date: 26 May 2012

Optical and current transport properties of CuO/ZnO nanocoral p–n heterostructure hydrothermally synthesized at low temperature

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We demonstrate the synthesis and investigate the electrical and optical characteristics of ‘nanocorals’ (NCs) composed of CuO/ZnO grown at low temperature through the hydrothermal approach. High-density CuO nanostructures (NSs) were selectively grown on ZnO nanorods (NRs). The synthesized NCs were used to fabricate p–n heterojunctions that were investigated by the current density–voltage (JV) and the capacitance–voltage (CV) techniques. It was found that the NC heterojunctions exhibit a well-defined diode behavior with a threshold voltage of about 1.52 V and relatively high rectification factor of ∼760. The detailed forward JV characteristics revealed that the current transport is controlled by an ohmic behavior for V≤0.15 V, whereas at moderate voltages 1.46≤V<1.5 the current follows a Jα exp(βV) relationship. At higher voltages (≥1.5 V) the current follows the relation JαV 2, indicating that the space-charge-limited current mechanism is the dominant current transport. The CV measurement indicated that the NC diode has an abrupt junction. The grown CuO/ZnO NCs exhibited a broad light absorption range that is covering the UV and the entire visible parts of the spectrum.