Single and double mode random lasing were observed in a polycrystalline ZnO nanorod array. The double mode random lasing showed mode competition when the mode spacing was 2.3 nm or below. Structurally, X-ray diffraction measurements confirmed the formation of the polycrystalline phase, and photoluminescence measurements revealed a broad visible peak due to point defects, suggesting enhanced oxygen diffusion due to annealing. Our results suggest polycrystalline nanorods prepared by chemical bath deposition as a material system for obtaining random lasing for optoelectronic applications and devices.

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