Influence of growth conditions on the threshold current density of double-heterostructure lasers prepared by molecular-beam epitaxy

The effect on threshold current density Jth of the use of an air-lock sample-exchange mechanism, substrate preparation and Al source purity was investigated for GaAs-Al0.27 Ga0.73 As double-heterostructure lasers grown by molecular-beam epitaxy (m.b.e.). The conditions necessary to prepare m.b.e. wafers that give Jth as low as for wafers prepared by liquid-phase epitaxy (Jth ? 1 × 103 A/cm2 for an active layer thickness of 0.1 ?m) are summarised.