Absorption enhancement in nanotextured solar cells with Ge/Si heterostructures

作者：Tayagaki Takeshi^*; Kishimoto Yuko; Hoshi Yusuke; Usami Noritaka

来源：Japanese Journal of Applied Physics, 2015, 54(4): 04DR03.

DOI：10.7567/JJAP.54.04DR03

Efficient light absorption is required to improve the efficiency of Ge/Si quantum dot solar cells. Here, we numerically investigate the impact of double-sided photonic nanostructures on near-infrared light absorption utilizing Ge/Si heterostructures. Extended absorption in the near-infrared region requires bottom nanostructures with an increased period compared with those of Si films with no Ge layer. The double-sided nanostructure developed here demonstrates both reduced reflection in the visible region and reduced transmission in the near-infrared region, enhancing the photocurrent up to 41.7 mA/cm(2). Although the Yablonovitch limit of the 100-nm-thick Ge layer allows sufficient absorption of more than 80% of the solar light in the 1100-1500 nm range to be used, further optimization of our double-sided nanostructures is necessary for this limit to be reached.

• 出版日期2015-4