Localized CO2 laser annealing induced dehydrogenation/ablation and optical refinement of silicon-rich silicon dioxide film with embedded si nanocrystals.
CO2 laser annealing induced effects of dehydrogenation, Si nanocrystal precipitation, ablation, and optical refinement in PECVD grown SiO1.25 film are investigated. Dehydrogenation shrinks SiO1.25 thickness by 40 nm after annealing at laser intensity (Plaser) of 4 kW/cm(2) for 1.4 ms. As Plaser increases to 6 kW/cm(2), the photoluminescence (PL) red-shifts to 806 nm due to the size enlargement of Si nanocrystals, while a reduced optical bandgap energy from 3.3 to 2.43 eV and an enlarged refractive index from 1.57 to 1.87 are also observed. Transmission electron microscopy analysis reveals that the randomly oriented Si nanocrystals exhibit an average diameter of 5.3 nm and a volume density of 1.9 x 10(18) cm(-3). CO2 Laser ablation initiates at intensity higher than 7 kW/cm(2), which introduces numerous structural defects with a strong PL at 410 nm. Such an ablation inevitably leads to a blue-shifted optical bandgap energy from 2.43 to 2.76 eV as Plaser enlarges from 6 to 12 kW/cm(2) are concluded.
Lin
Gong-Ru
GR
Graduate Institute of Electro-Optical Engineering and Department of Electrical Engineering, National Taiwan University, 1, Section 4, Taipei 106, Taiwan, Republic of China.
Lin
Chun-Jung
CJ
Chou
Li-Jen
LJ
Chueh
Yu-Lun
YL
D003460:Crystallization / Q000379:methods*; D006358:Hot Temperature; D006859:Hydrogen / Q000737:chemistry; D007834:Lasers; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics; D010316:Particle Size; D012031:Refractometry; D012825:Silicon / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
D046911:Macromolecular Substances; D008567:Membranes, Artificial; D012822:Silicon Dioxide; D006859:Hydrogen; D012825:Silicon