Formation of light-trapping structure using Ge islands grown by gas-source molecular beam epitaxy as etching masks

A high-performance light-trapping structure for Si was fabricated with an etching margin of only ∼1 µm using Ge islands grown by gas-source molecular beam epitaxy as etching masks. KOH solution containing isopropyl alcohol and HF + H2O2 + CH3COOH mixed solution were used as etchants. The reflectance of the structure was shown to be comparable to that of a conventional pyramid texture, which requires a larger etching margin of ∼10 µm. In addition, a potential short-circuit current density (p-Jsc) of 42.3 mA/cm2 was obtained for the sample after the deposition of indium tin oxide, which confirms that the light-trapping structure is applicable to crystalline Si solar cells with thinner wafers.