Improved luminescence from quantum-dot nanostructures embedded in structurally engineered (In,Ga)As confining layers

Efficient luminescence of quantum-dot nanostructures embedded in active regions of lasers is important for low-threshold current density devices. This paper discusses an approach for structurally engineering confining (In,Ga)As layers into which InAs quantum dots are inserted to enhance their emission efficiency. It is shown that by inserting the dots at the center of compositionally graded In_xGa_1-xAs layers, the relative emission efficiency can be increased by nearly an order of magnitude over the emission of dots inside a constant composition (In,Ga)As structure. This enhancement is thought to be a result of the high structural and optical quality of the confining layers.