Very low current threshold GaAs-AlxGa1−xAs double-heterostructure lasers grown by molecular beam epitaxy

GaAs-AlxGa1−xAs (x=0.3) double-heterostructure (DH) lasers having very low current threshold densities have been prepared by molecular beam epitaxy (MBE). For DH lasers having Al-mole-fraction differences between the active layers and AlxGa1−xAs confinement layers Δx∼0.3, the best of the MBE-grown DH laser wafers have averaged current threshold densities similar to those obtained from the best of similar-geometry DH lasers prepared by liquid-phase epitaxy (LPE) and by metalorganic chemical vapor deposition (MO-CVD). With Δx=0.3, the lowest averaged current threshold density achieved is 800 A/cm2 (without reflective coating) for a wafer with an active layer thickness of 0.15 μm.