Fabrication of Well-aligned ZnO Nanorods Architectures on InGaN-based Light Emitting Diodes with Seed Layer via Chemical Bath Deposition

• Main Authors: Ming-Shiou Lin, 林明秀
• Other Authors: Chia-Feng Lin
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/26929138356691068953

博士 === 國立中興大學 === 材料科學與工程學系所 === 99 === In this thesis, our experiments were performed as two parts. For the first experiment, the ZnO nanorod arrays were selective-growth on a p-type GaN:Mg layer effectively through a chemical bath deposition (CBD) at a low temperature hydrothermal synthesis (85oC) with a ZnO seed layer. The 5μm-diameter hole-array patterns of the ZnO seed layer were grown on a p-type GaN:Mg layer in aqueous solution with a mercury lamp illumination. The diameter and the height of ZnO nanorods were measured as the values of 500nm and 3μm, respectively. The preferred orientation, the surface morphology, and the aspect ratio of the ZnO nanorods can be controlled and formed on the hole-array patterned ZnO seed layer. The peak wavelength of the photoluminescence spectrum was measured at 384 nm For the second experiment, chemical bath deposition and mercury lamp illumination were used to synthesize ZnO nanorods (Zinc oxide Nanorods on Sputtering seed layer, ZNS) on aluminum zinc oxide (AZO) seed layer deposited by sputtering and then micro hole array (Micro-Hole Array, MHA) was utilized to control the growth of ZnO nanorods. ZnO nanorods (Zinc oxide Nanorods on Pulsed laser deposition seed layer, ZNP) was cultivated on AZO seed layer deposited by pulsed laser deposition on the light-emitting diode (LED) for various analysis and measurements. The field emission scanning electron microscopy and lower X-ray diffractometer were used to observe the AZO seed layer and the ZnO nanorods. The surface morphology of AZO seed layer deposited by pulsed laser deposition (PLD) has clear boundaries and obvious grains that indicated excellent crystallinity along the (002) preferred orientation. The well-aligned ZnO nanorod structure preferred oriented along the (002) direction was deposited on the AZO seed layer through a chemical bath deposition process. The ZnO nanorods structures and preferred orientation were also demonstrated shown in the micrograph of the field emission high resolution transmission electron microscopy. The photoluminescence intensity of the ZNP LED is higher than ZNS LED that indicated the higher optical property of the ZnO nanorods grown on the PLD deposited AZO seed layer. 　　The light output power of ZNP LED and ZNS LED have 54.3% and 40.7% enhancement compared to the standard LED devices at 20mA injection current. According to divergence angle measurement, we observed the difference of ZNP LED and ZNS-MHA LED, which results from the structures of ZnO nanorods affect the light extraction mechanism. ZnO nanorods structures are fabricated by chemical bath deposition with mercury lamp illuminated have potential applications on the InGaN-based LEDs to increase the light extraction efficiency.