chih-hung Wu - Academia.edu (original) (raw)

Papers by chih-hung Wu

Thin Solid Films, 2015

Abstract Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu sub... more Abstract Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu substrate at a low solution temperature of 90 °C. Continuous CuCl films were prepared using the copper (II) chloride (CuCl2) compound as the precursor for both the Cu2 + and Cl− sources, together with repeated HCl dip treatments. An HCl dip pretreatment of the substrate favored the nucleation of CuCl crystallites. Further, interrupting the film deposition and including an HCl dip treatment of the film growth surface facilitated the deposition of a full-coverage CuCl film. A dual beam (FIB/SEM) system with energy dispersive spectrometry facilities attached revealed a homogeneous CuCl layer with a flat-top surface and an average thickness of about 1 μm. Both the excitonic and biexcitonic emission lines were well-resolved in the 6.4 K photoluminescence spectra. In particular, the free exciton emission line was observable at room temperature, indicating the good quality of the CuCl films prepared by CBD.

IEEE Electron Device Letters, 2015

ABSTRACT We report the fabrication of a complementary electrochromic device (CECD) in the form of... more ABSTRACT We report the fabrication of a complementary electrochromic device (CECD) in the form of glass/indium-tinoxide (ITO)/NiO/gel-polymer electrode (GPE)/MoO3/ITO/glass, and the integration of a CECD/GaAs-based triple-junction (TJ) solar cell system. It was found that the maximum transmittance in the bleached state was 68.05% at 580 nm. With a solar radiation intensity of 100 mW/cm2, it was found that an optical contrast in transmittance at 580 nm could reach 58.73%. It was also found that the coloration time and bleaching time of the integration CECD/TJ solar cell system were 6 and 15 s, respectively.

International Journal of Photoenergy, 2015

The optoelectric properties of GaInP p-i-n solar cells with different intrinsic layer (i-layer) t... more The optoelectric properties of GaInP p-i-n solar cells with different intrinsic layer (i-layer) thicknesses from 0.25 to 1 μm were studied. Both emission intensity and full width at half maximum features of the photoluminescence spectrum indicate that the optimum i-layer thickness would be between 0.5 and 0.75 μm. The integrated current results of photocurrent experiment also point out that the samples with 0.5 to 0.75 μm i-layer thicknesses have optimum value around 156 nA. Electroreflectance measurements reveal that the built-in electric field strength of the sample gradually deviates from the theoretical value larger when i-layer thickness of the sample is thicker than 0.75 μm.I-Vmeasurements also confirm crystal quality for whole samples by obtaining the information about short currents of photovoltaic performances. A series of experiments reflect that thicker i-layer structure would induce more defects generation lowering crystal quality.

RSC Adv., 2015

The effect of graphene quantum dots (GQDs) on the enhancement of PL in GaAs epilayers has been de... more The effect of graphene quantum dots (GQDs) on the enhancement of PL in GaAs epilayers has been demonstrated and interpreted by carrier transfer due to the work function difference.

Progress in Photovoltaics: Research and Applications, 2012

Optics Express, 2008

We studied the photoluminescence (PL) and photovoltaic current-voltage characteristics of the thr... more We studied the photoluminescence (PL) and photovoltaic current-voltage characteristics of the three-junction InGaP/InGaAs/Ge solar cells by depositing Au nanoclusters on the cell surface. The increases of the PL intensity and short-circuit current after incorporation of Au nanoclusters are evident. An increase of 15.3% in energy conversion efficiency (from 19.6 to 22.6%) is obtained for the three-junction solar cells in which Au nanoclusters have been incorporated. We suggest that the increased light trapping due to radiative scattering from Au nanoclusters is responsible for improving the performance of the three-junction solar cells.

Journal of Crystal Growth, 2013

CuZnInSe 2 (CZIS) has potential application in solar cell for absorption layer, and give an advan... more CuZnInSe 2 (CZIS) has potential application in solar cell for absorption layer, and give an advantage to change the band gap from CuInSe 2 (1.02 eV) to ZnSe (2.67 eV). Using molecular beam epitaxy technology, the CZIS thin films were grown via CuInSe (CIS) and ZnSe base. In the case of CIS, thin films were grown on Mo-coated soda lime glass with various zinc flux. CIS was transformed into chalcopyrite and sphalerite coexisting CZIS easily but it is difficult to transform into the pure sphalerite CZIS. Zn/(Znþ Inþ Cu) ratio has limited to approximate 36 at% and the excess-Zn played a catalyst role. In the case of ZnSe base, which was grown on GaAs (001), various In and Cu flux defined as the T In series and T Cu series, respectively. There are four types of compound in the T In series and T Cu series, including ZnSe, In x Se y , ZnIn 2 Se 4 (ZIS) and CZIS. In the T In series under the lowest In and Cu flux, selenium (Se) were randomly combined with cations to form the CZIS. When T In is increased in this moment, the CZIS was transformed into ZIS. In the T Cu series, CZIS demonstrated via In-rich ZIS (Zn(In, Cu)Se) and In x Se y base ((Zn, Cu)InSe). It is chalcopyrite and sphalerite coexisting structure in the medium T Cu region. In the high T Cu region, it is transformed into the Zn-poor and Cu-rich CZIS.

Journal of Applied Physics, 2010

In this study, ZnSe1-xOx layers with oxygen contents of up to 7.0% are successfully grown at 300 ... more In this study, ZnSe1-xOx layers with oxygen contents of up to 7.0% are successfully grown at 300 °C on semi-insulating GaAs substrates by molecular beam epitaxy. The deposited ZnSe1-xOx films are characterized by Raman spectroscopy and the optical properties studied by spectroscopic ellipsometry. We examine the complex dielectric function obtained by spectroscopic ellipsometry in the photon range from 1.5 to

Journal of Alloys and Compounds, 2014

This work demonstrates an improvement of the molecular beam epitaxial growth of CdTe(1 1 1)A epil... more This work demonstrates an improvement of the molecular beam epitaxial growth of CdTe(1 1 1)A epilayer on Si(1 1 1) substrates using Mn atoms. The reflection high-energy electron diffraction patterns show that the involvement of some Mn atoms in the growth of CdTe(1 1 1)A is even more effective than the use of a buffer layer with a smooth surface for forming good CdTe(1 1 1)A epilayers. 10 K Photoluminescence spectra show that the incorporation of only 2% Mn significantly reduced the intensity of defect-related emissions and considerably increased the integral intensity of exciton-related emissions by a large factor of about 400.

Japanese Journal of Applied Physics, 2011

International Journal of Hydrogen Energy, 2010

IEEE Transactions on Electron Devices, 2010

In 0.16 Ga 0.84 As solar cells grown on GaAs substrates with different miscut angles via metalorg... more In 0.16 Ga 0.84 As solar cells grown on GaAs substrates with different miscut angles via metalorganic chemical vapor deposition were utilized to study the effect of substrate orientation on solar cell efficiency. A p-n In 0.16 Ga 0.84 As solar cell grown on a 2 •-off GaAs substrate exhibited better conversion efficiency than one grown on a 15 •-off GaAs substrate. The poor performance of the 15 •-off In 0.16 Ga 0.84 As solar cell could be attributed to the formation of high-density misfit dislocations through strain relaxation, thereby reducing the minority carrier lifetime. The conversion efficiency of a 15 •-off In 0.16 Ga 0.84 As solar cell was improved using a p-in structure. Using the p-in structure design, a 15 •-off In 0.16 Ga 0.84 As solar cell showed conversion efficiency close to or even better than that of a 2 •-off In 0.16 Ga 0.84 As solar cell with the same structure. Index Terms-In 0.16 Ga 0.84 As solar cells, miscut angles, p-in structure. I. INTRODUCTION C URRENTLY available high-efficiency III-V solar cells consist of three lattice-matched junctions grown on single crystal Ge substrates. The bandgaps of the three latticematched junctions are 1.83, 1.42, and 0.65 eV, respectively. This mature and lattice-matched design has achieved 40.1% efficiency at a 135-sun concentration [1]. However, the latticematched approach is not an optimum bandgap combination that can maximize photovoltaic conversion efficiency from the solar spectrum [2], [3]. A more appropriate approach might be a lattice-mismatched metamorphic design. Geisz et al. [4] reported on a conversion efficiency of 40.8% at 326 suns using the bandgap combinations of 1.83 eV (In 0.49 Ga 0.51 P,

IEEE Journal of Selected Topics in Quantum Electronics, 1997

It is shown that Coulomb enhancement (CE) has a significant influence on the spectral characteris... more It is shown that Coulomb enhancement (CE) has a significant influence on the spectral characteristics of optical gain and spontaneous emission in strained InGaAs quantum wells. CE-modified gain spectra are utilized to make an accurate prediction of the dependence of lasing wavelength on cavity length, Threshold-current predictions using the CE-modified gain-current relation show improved agreement with experiment

Journal of Crystal Growth, 2006

... Taiwan. c Institute of Optical Science, National Central University, Chung-Li 32054, Taiwan. ... more ... Taiwan. c Institute of Optical Science, National Central University, Chung-Li 32054, Taiwan. ... surface. After loading, first the Si substrate was thermally etched at 1005 °C under an H 2 +HCl ambient for 10 min to remove surface oxide. ...