Multilayers of InGaAs Nanostructures Grown on GaAs(210) Substrates

Multilayers of InGaAs nanostructures are grown on GaAs(210) by molecular beam epitaxy. With reducing the thickness of GaAs interlayer spacer, a transition from InGaAs quantum dashes to arrow-like nanostructures is observed by atomic force microscopy. Photoluminescence measurements reveal all the samples of different spacers with good optical properties. By adjusting the InGaAs coverage, both one-dimensional and two-dimensional lateral ordering of InGaAs/GaAs(210) nanostructures are achieved

Investigation of electrically active defects in InGaAs quantum wire intermediate-band solar cells using deep-level transient spectroscopy (DLTS) technique

InGaAs quantum wire (QWr) intermediate-band solar cell based nanostructures grown by molecular beam epitaxy are studied. The electrical and interface properties of these solar cell devices, as determined by current–voltage (I–V) and capacitance–voltage (C-V) techniques, were found to change with temperature over a wide range of 20–340 K. The electron and hole traps present in these devices have been investigated using deep-level transient spectroscopy (DLTS). The DLTS results showed that the traps detected in the QWr-doped devices are directly or indirectly related to the insertion of the Si δ-layer used to dope the wires. In addition, in the QWr-doped devices, the decrease of the solar conversion efficiencies at low temperatures and the associated decrease of the integrated external quantum efficiency through InGaAs could be attributed to detected traps E1QWR_D, E2QWR_D, and E3QWR_D with activation energies of 0.0037, 0.0053, and 0.041 eV, respectively

Quantum Beats in Hybrid Metal–Semiconductor Nanostructures

We investigate nonradiative quantum coherence in the presence of coupling between excitons and surface plasmon polaritons (SPPs) in a hybrid metal–semiconductor nanostructure. In particular, we study how quantum coherence between heavy-hole (HH) and light-hole (LH) excitons in a GaAs quantum well (QW) is modified when they are coupled to SPPs of a gold grating. We find that the nonradative coherence is reduced in correlation with the coupling strength between the excitons and SPPs. Under the resonant coupling condition, the nonradiative coherence remains in the range of hundreds of femtoseconds, which is significantly longer than the plasmonic coherence. These experiments directly probe quantum dynamics in a prototypical hybrid system and provide critical information for exploring future quantum plasmonics applications