Submilliampere Threshold Current InGaAs–GaAs–AlGaAs Lasers and Laser Arrays Grown on Nonplanar Substrates

High performance buried heterostructure InGaAs–GaAs–AlGaAs quantum-well lasers and laser arrays with tight spatial confinement of the electrical current and the optical fields have been fabricated by metalorganic chemical vapor deposition. The lasers are fabricated in a single growth step, using nonplanar substrates as a template for the active region definition. CW room temperature threshold currents, as low as 0.5 mA and 0.6 mA, are obtained for as-cleaved double and single quantum-well lasers, respectively. External quantum efficiencies exceeding 80% are obtained in the same devices. High-reflectivity facet-coated lasers have room temperature CW threshold currents as low as 0.145 mA with 10% external quantum efficiency. Lasers made by this technique have high yield and uniformity, and are suitable for low threshold array applications.