Abstract: A monolithic semiconductor device extends primarily along a vertical direction and includes the following layers. A first semiconductor layer and a second semiconductor layer form an active region between them. A third semiconductor layer is doped the same type as the second semiconductor layer but is lattice mismatched to the second semiconductor layer. The lattice mismatch results in unwanted electrical effects. An additional doping layer, preferably a delta doping layer, is located in close proximity to the interface between the second and third semiconductor layers. The delta doping layer mitigates the unwanted electrical effects introduced by the lattice mismatch. In a preferred embodiment, the device further includes a bottom mirror layer and a top mirror layer, which together form a laser cavity including the active region.