Browsing by Author "Liao, Shun Sing"

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Effect of surface passivation by a low pressure and temperature environment-grown thermal oxide layer for multi-crystalline silicon solar cells
(2018-08-30)
Liao, Shun Sing
;
Chuang, Chuan Lung
;
Lin, Yueh Chin
;
Dee, Chang Fu
;
Majlis, Burhanuddin Yeop
In this study, we show that the efficiency and carrier life time of multi-crystalline silicon solar cells were significantly improved by using a low pressure (20,000 Pa) and temperature (650 degrees C similar to 750 degrees C) environment grown thermal oxide (TO) as the surface passivation layer. In this experiment, during the first stage, the oxidation process was done at 650 degrees C and a lower pressure of 20,000 Pa for 2 mins under the flow a gas mixture of N-2/O-2 in ratio of 2:1. In the second stage, a temperature of 750 degrees C was used at the same pressure for the post-growth annealing process under a pure N-2 ambient for 25 mins. Consequently, conversion efficiency was significantly increased by 0.55% with the surface passivation layer grown by low pressure and temperature TO process. The sheet resistance, carrier lifetime, internal quantum efficiency (IQE), increased by 6.32 Omega/sq., 22.18 mu s, 4.33%, respectively, and the average reflection was reduced of 0.62%. Thus, the low pressure and temperature thermal oxidation process was an efficient way to increase the efficiency of the multi-crystalline silicon solar cells.
Efficiency Enhancement of Multicrystalline Silicon Solar Cells by Inserting Two-Step Growth Thermal Oxide to the Surface Passivation Layer
(2017-01-01)
Liao, Shun Sing
;
Lin, Yueh Chin
;
Chuang, Chuan Lung
;
Chang, Edward Yi
;
材料科學與工程學系
In this study, the efficiency of the multicrystalline was improved by inserting a two-step growth thermal oxide layer as the surface passivation layer. Two-step thermal oxidation process can reduce carrier recombination at the surface and improve cell efficiency. The first oxidation step had a growth temperature of 780 degrees C, a growth time of 5 min, and with N-2/O-2 gas flow ratio 12 : 1. The second oxidation had a growth temperature of 750 degrees C, growth time of 20 min, and under pure N-2 gas environment. Carrier lifetime was increased to 15.45 mu s, and reflectance was reduced 0.52% using the two-step growth method as compared to the conventional one-step growth oxide passivation method. Consequently, internal quantum efficiency of the solar cell increased 4.1%, and conversion efficiency increased 0.37%. These results demonstrate that the two-step thermal oxidation process is an efficient way to increase the efficiency of the multicrystalline silicon solar cells.