GeSn Vertical Heterostructure p-i-n Waveguide Light Emitting Diode for 2 μm Band Silicon Photonics

We demonstrate an electrically-injected GeSn $\textit {p-i-n}$ waveguide light emitting diode on silicon, comprising a vertical Ge/GeSn/Ge double-barrier heterostructure for $2 ~\mu \text{m}$ wavelength band integrated photonics. The incorporation of 4.2% Sn into the GeSn active layer results in bandgap shrinkage and extends the operating range to 2200 nm. Our design of the double-barrier heterostructure with the waveguide provides good carrier and optical confinement. The electroluminescence spectra at different current injection densities were measured at room temperature, demonstrating the peak wavelength at 1962 nm with the cutoff at 2200 nm, covering the entire $2 ~\mu \text{m}$ wavelength band. The results show that the proposed vertical $\textit {p-i-n}$ heterostructure GeSn diode opens a pathway to meeting the demand for group IV-based light sources required for $2 ~\mu \text{m}$ wavelength band integrated photonics.