Room-temperature direct-bandgap electroluminescence from type-I GeSn/SiGeSn multiple quantum wells for 2 μm LEDs

Two Ge1-xSnx/Si0.1Ge0.85Sn0.05 (x = 7.3% and 8.5%) multi-quantum wells (MQWs) based light emitting diodes (LEDs) were designed and fabricated to achieve efficient light emission in the similar to 2 mu m wavelength band. Electroluminescence (EL) at wavelengths of 1980 nm (0.626 eV) and 2060 nm (0.602 eV) from the MQWs light emitting diodes were observed at room temperature. Super-linear dependence between the injected current density and EL intensity illustrates the high band-to-band radiative recombination efficiency. Theoretical calculations using deformation potentials theory reveal that the type-I band alignment is formed, and correspond well with the quantum confinement effect of the direct-bandgap transitions of n(1 Gamma)- n(1HH). These results indicate that GeSn/SiGeSn MQW-LEDs is a promising full group-IV silicon-based light source in the 2 mu m waveband.