Greatly enhanced optical properties of ZnO nanorods grown on GaN in aqueous solution by using two-step treatment method

Abstract

ZnO nanorods with good optical properties were synthesized on GaN film by combining the lowerature growth aqueous solution method and the two-step postgrowth treatment method (thermal annealing and nitrogen plasma treatment). The photoluminescence results at room temperature showed that the nitrogen plasma treated ZnO nanorods exhibited a strong UV emission peak with negligible deep level emission peak compared to that of nonplasma-treated samples. The plasma-treated nanorods also exhibited strong stimulated emission with a threshold of 4.16 MW cm2 at room temperature. No stimulated emission was observed in the as-grown and thermal annealed nanorods. The X-ray photoelectron spectroscopy confirmed the incorporation of nitrogen ions into the ZnO nanorods. These ions may diffuse through surface adsorption or defect routes. In addition, nitrogen incorporation also offers a prospective way to produce ZnO nanorods with p-type conductivity or compensate the n-type conductivity. The current-voltage measurements showed the rectifying behavior with a small threshold voltage. © 2008 The Electrochemical Society.