Quantum dot strain engineering for light emission at 1.3, 1.4 and 1.5 µm

We designed and prepared by molecular beam epitaxy strain-engineered InAs/InGaAs/GaAs quantum dot (QD) nanostructures where we separately controlled: (i) the mismatch f between QDs and confining layers (CLs), and, then, the QD strain, by changing the thickness of a partially relaxed InGaAs lower CL and (ii) the CL composition x. The appropriate values of f and x to tune the emission energies at wavelengths in the 1.3-1.55 mu range were calculated by means of a simple model. Comparing model calculations and activation energies of photoluminescence quenching, we also concluded that quenching is due to both intrinsic and extrinsic processes; we show that the structures can be designed so as to maximize the activation energy of the intrinsic process, while keeping the emission energy at the intended value in the 1.3-1.55 mu range.