標題: Enhanced Free Exciton and Direct Band-Edge Emissions at Room Temperature in Ultrathin ZnO Films Grown on Si Nanopillars by Atomic Layer Deposition
作者: Chang, Yuan-Ming
Shieh, Jiann
Chu, Pei-Yuan
Lee, Hsin-Yi
Lin, Chih-Ming
Juang, Jenh-Yih
材料科學與工程學系
電子物理學系
Department of Materials Science and Engineering
Department of Electrophysics
關鍵字: ultrathin;ZnO;Si nanopillars;atomic layer deposition;free exciton
公開日期: 1-十一月-2011
摘要: Room-temperature ultraviolet (UV) luminescence was investigated for the atomic layer deposited ZnO films grown on silicon nanopillars (Si-NPs) fabricated by self-masking dry etching in hydrogen-containing plasma. For films deposited at 200 degrees C, an intensive UV emission corresponding to free-exciton recombination (similar to 3.31 eV) was observed with a nearly complete suppression of the defect-associated broad visible range emission peak. On the other hand, for ZnO films grown at 25 degrees C, albeit the appearance of the defect-associated visible emission, the UV emission peak was observed to shift by similar to 60 meV to near the direct band edge (3.37 eV) recombination emission. The high-resolution transmission electron microscopy (HRTEM) showed that the ZnO films obtained at 25 degrees C were consisting of ZnO nanocrystals with a mean radius of 2 nm embedded in a largely amorphous matrix. Because the Bohr radius of free-exictons in bulk ZnO is similar to 2.3 nm, the size confinement effect may have occurred and resulted in the observed direct band edge electron-hole recombination. Additionally, the results also demonstrate order of magnitude enhancement in emission efficiency for the ZnO/Si-NP structure, as compared to that of ZnO directly deposited on Si substrate under the same conditions.
URI: http://dx.doi.org/10.1021/am201062t
http://hdl.handle.net/11536/14668
ISSN: 1944-8244
DOI: 10.1021/am201062t
期刊: ACS APPLIED MATERIALS & INTERFACES
Volume: 3
Issue: 11
起始頁: 4415
結束頁: 4419
顯示於類別:期刊論文


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