Browsing by Author "Huang, Yen-Tang"

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Applications of mu c-SiOx:H as integrated n-layer and back transparent conductive oxide for a-Si:H/mu c-Si:H tandem cells
(2014-05-01)
Liang, Shin-Wei
;
Huang, Yen-Tang
;
Hsu, Hung-Jung
;
Hsu, Cheng-Hang
;
Tsai, Chuang-Chuang
We have prepared n-type hydrogenated microcrystalline silicon oxide [mu c-SiOx:H(n)] films with oxygen contents from 0 to 37.3 at. % by varying the CO2-to-SiH4 flow ratio in a plasma-enhanced chemical vapor deposition (PECVD) system. By using mu c-SiOx:H(n) as an effective replacement for integrated mu c-Si:H(n) and indium-tin oxide (ITO), mu c-Si:H single-junction and a-Si:H/mu c-Si:H tandem cells exhibited significantly improved efficiencies of 6.35 and 10.53%, respectively. The improvement of the single-junction and tandem cells mainly arose from the enhancement of long-wavelength optical absorption in mu c-Si:H absorbers, which was confirmed by a quantum efficiency instrument showing a markedly enhanced spectral response at wavelengths from 600 to 1100 nm. Moreover, all the PECVD processes, except the metal contact, had an advantage of in situ deposition without breaking vacuum, thereby minimizing contamination of the interface. The simplified cell fabrication can enhance the fill factor, which will benefit industrial production. (C) 2014 The Japan Society of Applied Physics
Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells
(2014)
Huang, Yen-Tang
;
Hsu, Hung-Jung
;
Liang, Shin-Wei
;
Hsu, Cheng-Hang
;
Tsai, Chuang-Chuang
Hydrogenated microcrystalline silicon-germanium (mu c-Si1-xGex:H) alloys were developed for application in Si-based thin-film solar cells. The effects of the germane concentration (R-GeH4) and the hydrogen ratio (R-H2) on the mu c-Si1-xGex:H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a-Si1-xGex:H and mu c-Si1-xGex:H were also compared. Similar to a-Si1-xGex:H, the preferential Ge incorporation was observed in mu c-Si1-xGex:H. Moreover, a higher R-H2 significantly promoted Ge incorporation for a-Si1-xGex: H, while the Ge content was not affected by R-H2 in mu c-Si1-xGex:H growth. Furthermore, to eliminate the crystallization effect, the 0.9 mu m thick absorbers with a similar crystalline volume fraction were applied. With the increasing R-GeH4, the accompanied increase in Ge content of mu c-Si1-xGex:H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization of R-H2 and R-GeH4, the single-junction mu c-Si1-xGex:H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared to mu c-Si:H cell, the external quantum efficiency at 800nm had a relative increase by 33.1%.
Enhancement of Spectral Response in mu c-Si1-xGex:H Thin-Film Solar Cells with a-Si:H/mu c-Si:H P-Type Window Layers
(2015-01-01)
Huang, Yen-Tang
;
Hsu, Cheng-Hang
;
Tsai, Chuang-Chuang
;
光電工程學系
;
光電工程研究所
The hydrogenated amorphous silicon (a-Si:H)/hydrogenated microcrystalline silicon (mu c-Si:H) double p-type window layer has been developed and applied for improving microcrystalline silicon-germanium p-i-n single-junction thin-film solar cells deposited on textured SnO2:F-coated glass substrates. The substrates of SnO2:F, SnO2:F/mu c-Si:H(p), and SnO2:F/a-Si: H(p) were exposed to H-2 plasma to investigate the property change. Our results showed that capping a thin layer of a-Si: H(p) on SnO2:F can minimize the Sn reduction during the deposition process which had H-2-containing plasma. Optical measurement has also revealed that a-Si: H(p) capped SnO2:F glass had a higher optical transmittance. When the 20 nm mu c-Si: H(p) layer was replaced by a 3 nm a-Si: H(p)/17 nm mu c-Si:H(p) double window layer in the cell, the conversion efficiency (eta) and the short-circuit current density (J(SC)) were increased by 16.6% and 16.4%, respectively. Compared to the standard cell with the 20 nm mu c-Si:H(p) window layer, an improved conversion efficiency of 6.19% can be obtained for the cell having a-Si:H(p)/mu c-Si: H(p) window layer, with V-OC = 490 mV, J(SC) = 19.50 mA/cm(2), and FF = 64.83%.
Improved light management in a-Si:H/a-Si1-xGex:H tandem cells by employing multi-functional n-type microcrystalline silicon oxide
(2014-05-01)
Hsu, Hung-Jung
;
Liang, Shin-Wei
;
Huang, Yen-Tang
;
Hsu, Cheng-Hang
;
Tsai, Chuang-Chuang
In this work, the development of plasma-enhanced chemical vapor deposition (PECVD) mu c-SiOx:H(n) and its application to a-Si:H/a-Si1-xGex:H tandem cells as the intermediate reflecting layer (IRL) and back reflector (BR) is presented. The n-type microcrystalline silicon oxide [mu c-SiOx:H(n)] was used as multifunctional layers in silicon thin-film solar cells owing to its wide bandgap and low refractive index. In the development of mu c-SiOx:H(n), increasing RF power increased film oxygen content, which widened the bandgap while reducing dark conductivity. Applying the mu c-SiOx:H to a-Si:H/a-Si1-xGex:H tandem cells as IRL and BR significantly improved cell performance. The mu c-SiOx:H(n) IRL increases the current of the top cell, thus improving the light management in a-Si:H/a-Si1-xGex:H tandem cells. On the other hand, the mu c-SiOx:H(n) can be used as the BR replacing the n-type a-Si:H and ITO layers. The mu c-SiOx:H increased cell conversion efficiency by 12.9% as IRL, and by 9.7% as BR, achieving 10.03% efficiency. (C) 2014 The Japan Society of Applied Physics
Optimization of mu c-Si1-xGex:H Single-Junction Solar Cells with Enhanced Spectral Response and Improved Film Quality
(2015-01-01)
Huang, Yen-Tang
;
Chen, Pei-Ling
;
Chen, Po-Wei
;
Hsu, Hung-Jung
;
Hsu, Cheng-Hang
Effects of RF power on optical, electrical, and structural properties of mu c-Si1-xGex:H films was reported. Raman and FTIR spectra from mu c-Si1-xGex:H films reflected the variation in microstructure and bonding configuration. Unlike increasing the germane concentration for Ge incorporation, low RF power enhanced Ge incorporation efficiency in mu c-Si1-xGex:H alloy. By decreasing RF power from 100 to 50 W at a fixed reactant gas ratio, the optical bandgap of mu c-Si1-xGex:H was reduced owing to the increase in Ge content from 11.2 to 23.8 at.%, while Ge-related defects and amorphous phase were increased. Consequently, photo conductivity of 1.62 x 10(-5) S/cm was obtained for the mu c-Si1-xGex:H film deposited at 60 W. By applying 0.9 mu m thick mu c-Si1-xGex:H absorber with X-C of 48% and [Ge] of 16.4 at.% in the single-junction cell, efficiency of 6.18% was obtained. The long-wavelength response of mu c-Si1-xGex:H cell was significantly enhanced compared with the mu c-Si:H cell. In the case of tandem cells, 0.24 mu m a-Si:H/0.9 mu m mu c-Si1-xGex:H tandem cell exhibited a comparable spectral response as 0.24 mu m a-Si:H/1.4 mu m mu c-Si:H tandem cell and achieved an efficiency of 9.44%.