Ge(111)-fin light-emitting diodes

Ge quantum wells perpendicular to a substrate, called Ge fins, have been fabricated by selectively oxidizing Si in SiGe grown epitaxially on an atomically flat Si(111) surface. The three-dimensional structure of the fins is suitable for relaxing the compressive strain induced by the lattice constant mismatch between the Si and Ge. The current voltage characteristics of Ge diodes show low dark currents, confirming the high crystalline quality of the Ge fins. By injecting forward currents into the Ge fins, we found direct recombinations at the Γ valley.