Room-Temperature Electrically Injected AlGaN-Based near-Ultraviolet Laser Grown on Si

This letter reports a successful fabrication of room-temperature electrically injected AlGaN-based near ultraviolet laser diode grown on Si. An Al-composition step down-graded AlN/AlGaN multilayer buffer was carefully engineered to not only tackle the huge difference in the coefficient of thermal expansion between AlGaN template and Si substrate, but also reduce the threading dislocation density caused by the large lattice mismatch. On top of the crack-free n-AlGaN template, high quality InGaN/AlGaN quantum wells were grown, sandwiched by waveguide and optical cladding layers, for the fabrication of edge-emitting laser diode. A dramatic narrowing of the electroluminescence spectral line width, an elongated far-field pattern, and a clear discontinuity in the slope of light output power plotted as a function of the injection current provide an unambiguous evidence of lasing.