Effect of surface passivation by a low pressure and temperature environment-grown thermal oxide layer for multi-crystalline silicon solar cells

Publication date: 30 August 2018
Source:Thin Solid Films, Volume 660
Author(s): Shun Sing Liao, Chuan Lung Chuang, Yueh Chin Lin, Chang Fu Dee, Burhanuddin Yeop Majlis, Edward Yi Chang
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 °C~750 °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 °C and a lower pressure of 20,000 Pa for 2 mins under the flow a gas mixture of N2/O2 in ratio of 2:1. In the second stage, a temperature of 750 °C was used at the same pressure for the post-growth annealing process under a pure N2 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 Ω/sq., 22.18 μs, 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.