Electroluminescence of $Si_{x}Ge_{1-x-y}Sn_{y}/Ge_{1-y}Sn_{y}$ pin-Diodes Grown on a GeSn Buffer

We present the growth, fabrication, and characterization of a $\text{Ge}_{1-y}Sn_{\mathrm{y}}$ pin-diode and a $\text{Si}_{\mathrm{x}}\text{Ge}_{1-\mathrm{x}-\mathrm{y}}\text{Sn}_{\mathrm{y}}/ \text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ pin-diode. The pin-diodes are grown by molecular beam epitaxy on a partially relaxed $\text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ buffer grown by reduce-pressure chemical vapor deposition. The analysis of the crystal shows that the $\text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ pin-diode is lattice-matched grown and the $\text{Si}_{\mathrm{x}}\text{Ge}_{1-\mathrm{x}-\mathrm{y}}\text{Sn}_{\mathrm{y}}/\text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ pin-diode is pseudomorphic grown with respect to the buffer. Temperature-dependent direct current measurements reveal a threshold voltage shift from 0.3 V to 0.55 V and a series resistance that shows metallic behavior. Furthermore, by comparing the electroluminescence spectra at 13.4 K and 293 K we observe a 10 times higher signal for the $\text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ pin-diode and a 3 times higher signal for the $\text{Si}_{\mathrm{x}}\text{Ge}_{1-\mathrm{x}-\mathrm{y}}\text{Sn}_{\mathrm{y}}/\text{Ge}_{1-\mathrm{y}}\text{Sn}_{\mathrm{y}}$ pin-diode at cryogenic temperatures. The peak energies at an injection current density of 2.5 kA/cm ² are 575 meV and 610 meV, respectively.