Pulsed-laser deposition of ZnO thin films and nanorods for photonic devices

ZnO thin film growth and ZnO nanorods growth on a Si (100) substrate through a two-step, off-axis pulsed laser deposition (PLD) are reported. ZnO morphologies were measured and the post-annealed ZnO films grown at T-g = 700 degrees C had very smooth surfaces and the rms roughness was about 0.5 nm. Finally, ZnO post-annealed buffer layer was inserted between ZnO epi-layer and GaN/sapphire substrates. It was confirmed by cathode luminescence (CL) spectrum that the ZnO film grown at 700 degrees C had very low visible luminescence, which means a decrease of the deep level defects. In the case of ZnO nanorods, controlling growth parameters during deposition enabled to adjust the dimensions of nanorods. The diameters of the grown nanorods ranged from 50 to 700 nm and the lengths are from 2 to 10 mu m. The CL spectra were used to evaluate the states of defects within the ZnO nanorods. According to the CL results, the thinnest nanorod arrays were found to have fewer defects, while more defects were inserted as nanorods became thicker.