Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure

Alguno, Arnold; Usami, Noritaka; Ujihara, Toru; Fujiwara, Kozo; Sazaki, Gen; Nakajima, Kazuo; Shiraki, Yasuhiro
August 2003
Applied Physics Letters;8/11/2003, Vol. 83 Issue 6, p1258
Academic Journal
We report on the performance of solar cells with stacked self-assembled Ge dots in the intrinsic region of Si-based p-i-n diode. These dots were epitaxially grown on p-type Si(100) substrate via the Stranski–Krastanov growth mode by gas-source molecular beam epitaxy. Enhanced external quantum efficiency (EQE) in the infrared region up to 1.45 μm was observed for the solar cells with stacked self-assembled Ge dots compared with that without Ge dots. Furthermore, the EQE was found to increase with increasing number of stacking. These results show that electron-hole pairs generated in Ge dots can be efficiently separated by the internal electric field, and can contribute to the photocurrent without considerable recombination in Ge dots or at Ge/Si interfaces. © 2003 American Institute of Physics.


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