Browsing by Author "Lin, Chun-Jung"

Now showing 1 - 12 of 12

Anomalous microphotoluminescence of high-aspect-ratio Si nanopillars formatted by dry-etching Si substrate with self-aggregated Ni nanodot mask
(2007-04-02)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
Kuo, Hao-Chung
;
Lin, Huang-Sheng
;
Kao, Chi-Chiang
Microphotoluminescence (mu-PL) of high-aspect-ratio Si nanopillars fabricated by etching Ni-nanodot/SiO2 masked Si substrate is investigated. The 320-nm-tall Si nanopillars obtained by CF4/Ar mixed inductively coupled-plasma reactive ion etching process with density of 2.8x10(10) cm(-2) further shrink size from 30 to 6 nm by oxidation and etching. Blue-green mu-PL with two decomposed wavelengths at 425 and 475 nm is attributed to oxygen-related defects on the oxidized Si nanopillar surface. Defect-related near-infrared PL at 703 and 740 nm remains unchanged, while a quantum-confinement-effect-dependent PL blueshifted from 874 to 826 nm as the Si nanopillar size reduces from 7.2 to 6.0 nm is preliminarily observed. (c) 2007 American Institute of Physics.
Aspect-ratio-dependent ultra-low reflection and luminescence of dry-etched Si nanopillars on Si substrate
(2009-01-01)
Pai, Yi-Hao
;
Meng, Fan-Shuen
;
Lin, Chun-Jung
;
Kuo, Hao-Chung
;
Hsu, Shih-Hsin
The Si nanopillars with high aspect ratio were fabricated by dry-etching the thin SiO(2)-covered Si substrate with a rapidly self-assembled Ni nanodot patterned mask. Aspect-ratio-dependent ultra-low reflection and anomalous luminescence of Si nanopillars are analyzed for applications in all-Si based lighting and energy transferring systems. The Si nanopillars induce an ultra-low reflectance and refractive index of 0.88% and 1.12, respectively, at 435 nm due to the air/Si mixed structure and highly roughened surface. The reflectance can be < 10% with a corresponding refractive index of < 1.80 between 190 and 670 nm. Lengthening the Si nanopillars from 150 +/- 15 to 230 +/- 20 nm further results in a decreasing reflectance, corresponding to a reduction in refractive index by Delta n/n = 18% in the visible and near-infrared wavelength region. After dry-etching an Si wafer into Si nanopillars, the weak blue-green luminescence with double consecutive peaks at 418-451 nm is attributed to the oxygen defect (O(2-))-induced radiation, which reveals less relevance with the ultra-low-reflective Si nanopillar surface.
Catalytically solid-phase self-organization of nanoporous SnS with optical depolarizability
(2016)
Cheng, Chih-Hsien
;
Chi, Yu-Chieh
;
Wu, Chung-Lun
;
Lin, Chun-Jung
;
Tsai, Ling-Hsuan
The catalytic solid-phase synthesis of self-organized nanoporous tin sulfide (SnS) with enhanced absorption, manipulative transmittance and depolarization features is demonstrated. Using an ultralow radio-frequency (RF) sputtering power, the variation of the orientation angle between the anodized aluminum oxide (AAO) membrane and the axis of the sputtered ion beam detunes the catalytically synthesized SnS from nanorod to nanoporous morphology, along the sidewall of the AAO membrane. The ultraslow catalytic sputtering synthesis on the AAO at the RF plasma power of 20 W and the orientation angle of 0 degrees regulates the porosity and integrality of nanoporous SnS, with average pore diameter of 80-150 nm. When transferring from planar to nanoporous structure, the phase composition changes from SnS to SnS2-Sn2S3, and the optical bandgap shrinks from 1.43 to 1.16 eV, due to the preferred crystalline orientation, which also contributes to an ultralow reflectance of <1% at 200-500 nm when both the transmittance and the surface scattering remain at their maxima. The absorption coefficient is enhanced by nearly one order of magnitude with its minimum of >5 x 10(4) cm(-1) at the wavelength between 200 and 700 nm, due to the red-shifting of the absorption spectrum to at least 100 nm. The catalytically self-organized nanoporous SnS causes strong haze and beam divergence of 20 degrees-30 degrees by depolarized nonlinear scattering at the surface, which favors the solar energy conversion with reduced surface reflection and enhanced photon scattering under preserved transmittance.
Characterization of Si nanorods by spectroscopic ellipsometry with efficient theoretical modeling
(2008-04-01)
Hsu, Shih-Hsin
;
Liu, En-Shao
;
Chang, Yia-Chung
;
Hilfiker, James N.
;
Kim, Young Dong
Spectroscopic ellipsometry (SE) is applied to characterize Si columnar nanostructures. By employing effective medium approximation (EMA) theory, Si nanorods are treated as a graded layer with each sub-layer modeled as a mixture of Si and voids with varying porosity fraction. In addition, the rigorous coupled-wave analysis and finite-element Green's function method were used in modeling Si nanorods as a stack of disks with varying diameters and thicknesses, and the calculations are in satisfactory agreement with the measurement results. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Enhanced, pumping energy transfer between si nanocrystals and erbium ions in Si-rich SiOx sputtered using Si/Er2O3 encapsulated SiO substrate
(2007-08-01)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
Chen, Chia-Yang
;
光電工程學系
;
Department of Photonics
We investigate the enhanced pumping energy transfer for near-infrared photoluminescence in highdensity Si nanocrystals (nc-Si) and Erbium ions co-cloped SiO, film, which is obtained by RF magnetron assistant sputtering the SiO target with partially encapsulated Si and Er2O, chips. In contrast to conventional approaches, the use of SiO instead of SiO2 or Si substrate facilitates the formation of nc-Si in the sputtered SiO,,, while the Er2O3 replaces the Er pellets to improves the Er3+ concentrations and prevent the precipitation of Er atoms in the nc-Si and Er3+ co-doped SiOx film. Er3+ ion concentration up to 0.325 atomic % is obtained in the SiOx:Er3+ film under a sputtering power of 100 Watts. Correlation between annealing parameters and energy transferring from nc-Si to Er3+ ions is demonstrated, which reveals an optimized annealing condition at 1000 degrees C for 240 min and highest energy transfer efficiency from 760 to 1535 nm by the nc-Si with size and density of 4.5 nm and loll cm(-3) is observed.
Enhancement of Fowler-Nordheim tunneling based light emission from metal-SiOx-Si MOSLED
(2006-01-01)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
光電工程學系
;
Department of Photonics
PECVD grown nanocrystallite Si structure at SiOx/Si interface has been demonstrated to show its capability in enhancing the surface roughness and the Fowler-Nordheim tunneling based carrier injection for improved light emission from a metal-SiOx-Si MOSLED.
Enhancing nanocrystallite si electroluminescence by suppressing oxygen decomposition in high-temperature and low-plasma-power PECVD
(2007)
Lin, Chun-Jung
;
Lin, Gong-Ru
;
光電工程學系
;
Department of Photonics
This work demonstrates enhanced electroluminescence and quantum efficiency of a metal-SiOx-Si light-emitting diode (MOSLED) fabricated on nanocrystallite Si (nc-Si)-embedded SiOx plasma-enhanced chemical vapor deposition (PECVD) grown at high substrate temperature and threshold plasma power. Electron energy loss spectroscopy indicates that the energy loss of the primary electron transmitted throughout Si-rich SiOx is reduced from 110 to 106 eV due to the formation of nc-Si. At low plasma power condition, the required dissociation energy of a N2O molecule exceeds that of a SiH4 molecule, while increasing the deposition temperature during PECVD growth facilitates the out-diffusion of adsorbed oxygen atoms. Such enhanced deposition of Si-rich SiOx with excess Si atoms and dense nc-Si after annealing is observed. As the deposition temperature for the Si-rich SiOx increases from 300 to 400 degrees C, the electroluminescent power and quantum efficiency of the nc-Si-based MOSLED are both improved by more than 1 order of magnitude. The output power, turn-on voltage, and internal and external quantum efficiency of the indium tin oxide/SiOx:nc-Si/p-Si/Al diode that was prepared at a substrate temperature of 400 degrees C are 47 nW at 54 mu A, 54.5 V, 5x10(-4), and 1.6x10(-5), respectively. (c) 2007 The Electrochemical Society.
Localized CO2 laser annealing induced dehydrogenation/ablation and optical refinement of silicon-rich silicon dioxide film with embedded Si nanocrystals
(2006-12-01)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
Chou, Li-Jen
;
Chueh, Yu-Lun
;
光電工程學系
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 (P-laser) of 4 kW/cm(2) for 1.4 ms. As P-laser 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 P-laser enlarges from 6 to 12 kW/cm(2) are concluded.
Microphotoluminescence and microphotoreflectance analyses of CO2 laser rapid-thermal-annealed SiOx surface with buried Si nanocrystals
(2006-09-01)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
Chou, Li-Jen
;
Chueh, Yu-Lun
;
材料科學與工程學系
The optical properties of a SiOx film rapid-thermal-annealed (RTA) by CO2 laser are primarily investigated. The microphotoluminescence (mu-PL) and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the precipitation of random-oriented Si nanocrystals can be initiated when laser intensity (P-laser) is larger than 4.5 kW/cm(2). At P-laser of 6 kW/cm(2), the Si nanocrystal exhibits a largest diameter of 8 run and a highest density of 4.5 x 10(16) cm(-3), which emits strong PL at 790-825 nm. The microphotoreflectance of the CO2 laser RTA SiOx film reveals a volume density product dependent refractive index increasing from 1.57 to 1.87 as P-laser increases from 1.5 to 7.5 kW/cm(2). Nonetheless, the laser ablation of the SiOx film occurs with a linear ablation slope of 35 nm/kW/cm(2) at beyond 7.5 kW/cm(2), which terminates the enlargement of Si nanocrystals, degrades the near-infrared PL, and slightly reduces the refractive index of the CO2 laser RTA SiOx film.
Near-infrared electroluminescence of furnace or CO2 laser annealed si-rich SiO2 with structural defects and Si nanocrystals
(2006)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
光電工程學系
;
Department of Photonics
Electroluminescence of the CO2 laser annealed PECVD-grown silicon-rich silicon oxide (SRSO) based metal-oxide-semiconductor diode with embedded Si nanocrystals is demonstrated. The structural and optical properties of a CO2 laser rapid thermal annealed Si-rich SiO1.25 film are investigated. The color of SiO1.25 film changes from light yellow to dark-yellow as the CO2 laser annealing intensity enlarges from 1.5 to 13.5 kW/cm(2). Such a color change is mainly attributed to both the increasing absorption coefficient and refractive index of the SiO1.25 film under the precipitation of Si nanocrystals. The thickness of the SiO1.25 film was thinned during the dehydrogenated process at a slightly lower laser intensity of 4 kW/cm(2), while the complete dehydrogenation is observed after annealing for 1.4 ms associated with a thickness shrinking from 280 mn to 240 nm. TEM analysis and pbotoluminescence spectroscopy at 806 nm reveal that the Si nanocrystals with maximum diameter and density of 5.3 nm and 10(18) cm(-3), respectively, can be precipitated as the CO2 laser intensity increase to an ablation threshold intensity of 5.8 kW/cm(2). The laser ablation introduces numerous structural defects and causes the anomalous absorption as well as photoluminescence at blue-green wavelengths in the SiO1.25 film. From the reflection spectra with enlarged interfering fringe amplitude, the increasing refractive index (from 1.57 to 1.88) of the SiO1.25 with increasing laser intensity can be concluded. In comparison with that of the quartz or as-grown sample, the red-shifted optical bandgap energy of the CO2 laser-annealed SiO1.25 film from 5.4 eV to 4 eV has evidenced the effect of the strong blue-green absorption on the oxygen vacancy defect. The forward turn-on voltage and current density of the ITO/CO2 laser annealed SRSO/p-Si/Al MOS diode are 79 V and 33 mu A/cm(2), respectively. The maximum output power of 29 nW associated with a P-I slope of 4.4 mW/A is determined.
Near-infrared electroluminescence of furnace or CO2 laser annealed si-rich SiO2 with structural defects and Si nanocrystals - art. no. 619515
(2006-01-01)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
光電工程學系
;
Department of Photonics
Electroluminescence of the CO2 laser annealed PECVD-grown silicon-rich silicon oxide (SRSO) based metal-oxide-semiconductor diode with embedded Si nanocrystals is demonstrated. The structural and optical properties of a CO2 laser rapid thermal annealed Si-rich SiO1.25 film are investigated. The color of SiO1.25 film changes from light yellow to dark-yellow as the CO2 laser annealing intensity enlarges from 1.5 to 13.5 kW/cm(2). Such a color change is mainly attributed to both the increasing absorption coefficient and refractive index of the SiO1.25 film under the precipitation of Si nanocrystals. The thickness of the SiO1.25 film was thinned during the dehydrogenated process at a slightly lower laser intensity of 4 kW/cm(2), while the complete dehydrogenation is observed after annealing for 1.4 ms associated with a thickness shrinking from 280 mn to 240 nm. TEM analysis and pbotoluminescence spectroscopy at 806 nm reveal that the Si nanocrystals with maximum diameter and density of 5.3 nm and 10(18) cm(-3), respectively, can be precipitated as the CO2 laser intensity increase to an ablation threshold intensity of 5.8 kW/cm(2). The laser ablation introduces numerous structural defects and causes the anomalous absorption as well as photoluminescence at blue-green wavelengths in the SiO1.25 film. From the reflection spectra with enlarged interfering fringe amplitude, the increasing refractive index (from 1.57 to 1.88) of the SiO1.25 with increasing laser intensity can be concluded. In comparison with that of the quartz or as-grown sample, the red-shifted optical bandgap energy of the CO2 laser-annealed SiO1.25 film from 5.4 eV to 4 eV has evidenced the effect of the strong blue-green absorption on the oxygen vacancy defect. The forward turn-on voltage and current density of the ITO/CO2 laser annealed SRSO/p-Si/Al MOS diode are 79 V and 33 mu A/cm(2), respectively. The maximum output power of 29 nW associated with a P-I slope of 4.4 mW/A is determined.
Optical characterization of CO2-laser-ablated Si-rich SiOx
(2007-04-09)
Lin, Gong-Ru
;
Lin, Chun-Jung
;
Chang, Yia-Chung
;
光電工程學系
;
Department of Photonics
Anomalous absorption and the corresponding change in the optical band gap of a CO2-laser-ablated Si-rich SiO2 (SiOx) film are studied. The optical band gap energy of as-grown nonstoichiometric SiOx is slightly reduced by increasing Si-Si bonds as compared to quartz. After rapid thermal annealing using a CO2 laser, the dehydrogenation of SiOx film further increases the Si-Si bonding states and redshifts the optical band gap by 1 eV. Laser ablation is initiated at a laser intensity of > 7.5 kW/cm(2), leaving numerous luminescent centers that are related to neutral oxygen vacancy defects, increasing the absorption coefficient and related optical band gap energy, and reducing the refractive index in partially annealed SiOx. (c) 2007 American Institute of Physics.