Undoped p-Type ZnO Nanorods Synthesized by a Hydrothermal Method


  • This work was supported by the Research Grants Council of The Hong Kong Special Administrative Region, China (Project Numbers HKU 7019/04P and HKU 7037/06P). Financial supports from the Strategic Research Theme, University Development Fund, and Seed Funding Grant and Outstanding Young Researcher Award (administrated by The University of Hong Kong) are also acknowledged. The authors would like to thank Prof. K. Y. Chan for the use of equipment for EIS measurement, Materials Characterization and Preparation Facility, HKUST for SIMS and XPS measurements, Science Park for XPS measurements, and S. L. Shi and S. J. Xu (HKU) for PL measurements.


Zinc oxide is a very promising material for short-wavelength light-emitting devices due to its large band gap and high exciton binding energy. Although great progress has been made in recent years, p-type doping and control over native defects introduced during or after material growth are still significant problems that hinder the development of efficient ZnO based optoelectronic devices. Here we demonstrate a versatile method for the growth or p-type or n-type ZnO nanorods from the same growth solution at temperature as low as 90 °C, where the conductivity type is controlled by the preparation of the seed layer for nanorod growth. The differences in the conductivity type can be attributed to dependency of native defect concentrations and hydrogen incorporation on the seed layer preparation method. Room temperature electroluminescence has been demonstrated from homojunction and heterojunction light emitting diodes containing p-ZnO nanorods.