Impurity-assisted terahertz luminescence in quantum well nanostructures under interband photoexсitation

Determination of the exciton formation in quantum wells from time-resolved interband luminescence.

We present the results of a detailed time-resolved luminescence study carried out on a very high quality InGaAs quantum well sample where the contributions at the energy of the exciton and at the band edge can be clearly separated. We perform this experiment with a spectral resolution and a sensitivity of the setup, allowing us to keep the observation of these two separate contributions over a ...

Population inversion in optically pumped asymmetric quantum well terahertz lasers

Quantum-confined electronic states in atomically well-defined graphene nanostructures.

Despite the enormous interest in the properties of graphene and the potential of graphene nanostructures in electronic applications, the study of quantum-confined states in atomically well-defined graphene nanostructures remains an experimental challenge. Here, we study graphene quantum dots (GQDs) with well-defined edges in the zigzag direction, grown by chemical vapor deposition on an Ir(111)...

Luminescence from amorphous silicon nanostructures.

We present a model of size-dependent luminescence from a-Si:H and show that a blueshift of the luminescence energy and a general increase in luminescence quantum efficiency are predicted as structure size decreases. In contrast to bulk a-Si:H structures, highly confined a-Si:H exhibits visible luminescence peak energies and high radiative quantum efficiency at room temperature, which is insensi...

Terahertz quantum cascade lasers based on intra-well optical transitions

The possibility to achieve laser action at different THz frequencies employing the so-called vertical transition will be discussed. The intra-well or vertical optical transition presents a number of features that makes it an ideal candidate for a systematic study of resonant tunnelling and dephasing in quantum cascade lasers. Laser action at 3.5 THz with very low threshold employing a single qu...