Browsing by Author "Liu, Chin-Hung"

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Fabrication of large-scale single-crystal Cu(In, Ga)Se-2 nanotip arrays solar cell by one-step ion milling processes
(2013-11-01)
Wang, Yi-Chung
;
Yen, Yu-Ting
;
Liu, Chin-Hung
;
Chen, Chia-Hsiang
;
Kuo, Wei-Chen
Template-free, one step formation of Cu(In, Ga)Se-2 (CIGS) nanotip arrays (NTRs) to enhance device efficiency were discussed. Through Ar+ ion milling process, the CIGS NTRs could be formed directly on the CIGS layer. The angles and lengths of CIGS NTRs could be precisely controlled by incident angle of Ar+ beam and milling time, respectively. Mechanisms were proposed to be a self-masking effect by Cu segregation formed at early stage confirmed by Transmission Electron Microscopy, Grazing Incidence X-ray Diffraction, Energy Dispersive Spectroscopy, and Auger Electron Spectroscopy. Measurements of devices on various KCN washing time and thickness of CdS buffer layer were reported to achieve the highest efficiency of CIGS NTRs devices. This approach provides one-step fast process without templates, easy integration with in-line sputtering process, and no post-selenizatoin process for the formation of CIGS nanostructure, which can stimulate great attention not only in academic investigations but also in industrial side for practical applications. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Large Scale Single-Crystal Cu(In,Ga)Se(2) Nanotip Arrays For High Efficiency Solar Cell
(2011-10-01)
Liu, Chin-Hung
;
Chen, Chia-Hsiang
;
Chen, Szu-Ying
;
Yen, Yu-Ting
;
Kuo, Wei-Chen
In this paper, we demonstrated direct formation of large area Cu(In,Ga)Se(2), nanotip arrays (GIGS NTRs) by using one step Ar(+) milling process without template. By controlling milling time and incident angles, the length of CIGS NTRs with adjustable tilting orientations can be precisely controlled. Formation criteria of these CIGS NTRs have been discussed in terms of surface curvature, multiple components, and crystal quality, resulting in a highly anisotropic milling effect. The CIGS NTRs have very low reflectance <0.1% at incident wavelengths between 300 to 1200 nm. Open circuit voltage and short circuit current of CIGS NTRs solar cell were measured to be similar to 390 mV and similar to 22.56 mA/cm(2), yielding the filling factor and the efficiency of 59 and 5.2%, respectively. In contrast to CIGS thin film solar cell with efficiency of 3.2%, the nanostructured CIGS NTRs can have efficiency enhancement of similar to 160% due to the higher light absorption ability because of the nanostructure. The merits of current approach include the latest way via template-free direct creating process of nanostructured CIGS NTRs with controllable dimensionality and large scale production without postselenization process.
Large Scale Single-Crystal Cu(In,Ga)Se-2 Nanotip Arrays For High Efficiency Solar Cell
(2011-10-01)
Liu, Chin-Hung
;
Chen, Chia-Hsiang
;
Chen, Szu-Ying
;
Yen, Yu-Ting
;
Kuo, Wei-Chen
In this paper, we demonstrated direct formation of large area Cu(In,Ga)Se-2, nanotip arrays (GIGS NTRs) by using one step Ar+ milling process without template. By controlling milling time and incident angles, the length of CIGS NTRs with adjustable tilting orientations can be precisely controlled. Formation criteria of these CIGS NTRs have been discussed in terms of surface curvature, multiple components, and crystal quality, resulting in a highly anisotropic milling effect. The CIGS NTRs have very low reflectance <0.1% at incident wavelengths between 300 to 1200 nm. Open circuit voltage and short circuit current of CIGS NTRs solar cell were measured to be similar to 390 mV and similar to 22.56 mA/cm(2), yielding the filling factor and the efficiency of 59 and 5.2%, respectively. In contrast to CIGS thin film solar cell with efficiency of 3.2%, the nanostructured CIGS NTRs can have efficiency enhancement of similar to 160% due to the higher light absorption ability because of the nanostructure. The merits of current approach include the latest way via template-free direct creating process of nanostructured CIGS NTRs with controllable dimensionality and large scale production without postselenization process.
Taper PbZr0.2Ti0.8O3 Nanowire Arrays: From Controlled Growth by Pulsed Laser Deposition to Piezopotential Measurements
(2012-03-01)
Chen, Yu-Ze
;
Liu, Te-Hsiang
;
Chen, Cheng-Ying
;
Liu, Chin-Hung
;
Chen, Szu-Ying
Single crystalline PbZr0.2Ti0.8 (PIT) nanowires arrays (NWAs) with taper morphology were epitaxially grown on SrTiO3 (STO) substrate using pulse laser deposition. The taper morphology was attributed to the overcoating of PIT layer via a lateral growth of Pit clusters/adatoms during PIT NW growth.. The growth window for PZT film or nanowire was systematically studied at varied temperatures and pressures. The proposed growth mechanism of the taper PIT NWAs was investigated from a layer by layer growth via Frank-Van Der Merwe growth, followed by a formation of three-dimensional islands via Stranski-Krastanow growth, and then axial growth on the lowest energy (001) plane with growth direction of [001] via vapor-solid growth mechanism. However, under certain conditions such as at higher or lower pressure (>400 or <200 mTorr) or substrate temperatures (>850 degrees C and <725 degrees C), formation of the PIT NWs is suppressed while the epltaxial Pit thin film via the layer-by-layer growth remains. The controllable growth directions of the PZT NWAs on (001), (110), and (111) STO substrates were demonstrated. The piezopotential of the taper PIT NWAs using a conducting atomic force microscope with the average voltage output of similar to 18 mV was measured. The theoretical piezopotential of a PIT NW was calculated to compare with the measured outputs, providing a comprehensively experimental and theoretical understanding of the piezoelectricity for the PZT NW.