GaAs-AlxGa1-xAs double-heterostructure (DH) lasers with Si-doped n-type active layers have been prepared by molecular-beam epitaxy (MBE) and the laser properties evaluated. With 0.2-μm-thick active layers and 300-μm cavity lengths, typical room-temperature threshold current densities Jthof A/cm2and best values of A/cm2have been obtained. Stripe-geometry devices were run CW up to 9°C. Photoluminescence (PL) studies of single layers grown with the donors Si, Ge, and Sn show that the luminescent intensity for MBE n-type layers depends on the substrate temperature during growth. The PL intensity for Sn-doped MBE layers was greater than for high-quality Sn-doped liquid-phase-epitaxial layers.