Electrically pumped Ge Laser at room temperature

The stimulated emission from (110) Ge was observed in the metal-insulator-semiconductor (MIS) laser diode with a simple Fabry-Perot cavity by current injection at room temperature. The lasing characteristics consist of (1) sudden increase of efficiency in the light-out current-in curve, (2) the transverse electrical mode polarization, (3) the strong directivity of the far field pattern, (4) the narrow line width in the emission spectra above the threshold, and (5) the population inversion confirmed by fitting the spontaneous emission spectrum near the threshold current. The lasing wavelength is suitable for Si photonics due to the emission energy lower the Si bandgap.