GaSb-based >3 µm laser diodes grown with up to 2.4% compressive strain in the quantum wells using strain compensation

• GaSb-based ~3.2 µm laser diodes are grown with large compressive strain in the QWs.
• Up to ~2.4% compressive strain is attained with the use of strain compensation.
• High strain appears to increase slope efficiency and reduce threshold current density.

We describe the growth of GaSb-based diode lasers with quinary AlInGaAsSb alloy waveguide/barriers and highly strained InGaAsSb type-I quantum wells, designed to emit at ~3.2 µm at room temperature. To increase the compressive strain in the QWs above the pseudomorphic limit, we employ strain compensation in which the lower portion of the quinary alloy waveguide is slightly arsenic-rich as compared to the lattice-matched composition. Using this scheme, we fabricated a set of laser devices with incrementally increasing compressive strain in the quantum wells. With compressive strain reaching as high as ~2.4%, the device performance corroborates the notion that adding compressive strain in the quantum wells helps improve hole confinement and suppresses carrier leakage during operation near room temperature.