We performed depth-resolved PL and Raman spectral mappings of a GaN-based LED structure grown on a patterned sapphire substrate (PSS). Our results showed that the Raman mapping in the PSS-GaN heterointerface and the PL mapping in the InxGa1-xN/GaN MQWs active layer are spatially correlated. Based on the 3D construction of E2(high) Raman peak intensity and frequency shift, V-shaped pits in the M...

In this research, nano-ring light-emitting diodes (NRLEDs) with different wall width (120 nm, 80 nm and 40 nm) were fabricated by specialized nano-sphere lithography technology. Through the thinned wall, the effective bandgaps of nano-ring LEDs can be precisely tuned by reducing the strain inside the active region. Photoluminescence (PL) and time-resolved PL measurements indicated the lattice-m...

Optically pumped green lasing with an ultra low threshold has been achieved using an InGaN/GaN based micro-disk with an undercut structure on silicon substrates. The micro-disks with a diameter of around 1 μm were fabricated by means of a combination of a cost-effective silica micro-sphere approach, dry-etching and subsequent chemical etching. The combination of these techniques both minimises ...

Dimethylformamide/dimethyl sulfoxide solvent mixtures were used as the CH₃NH₃PbI₃ (MAPbI₃) precursor solvent in a one-step spin coating method to fabricate smooth and hydrophilic crystalline MAPbI₃ thin films on top of hydrophobic carbon-60 (C60) thin film for highly efficient photovoltaics. The structural, optical, and excitonic characteristics of the resultant MAPbI₃ thin films were analyzed ...

The exciton dynamics in In0.15Ga0.85As/GaAs quantum wells grown on (111)B and (100) GaAs substrates are studied by the time-resolved photoluminescence (PL). We have found that the piezoelectric fields in (111)B samples affect the transient behavior of PL spectra. Compared with the reference (100) samples, we have confirmed that the piezoelectric effect induces slower exciton relaxation in (111)...

ANOSTRUCTURED silicon has been intensely studied for over 15 years as a potential enabling material for silicon photonics [1]. Typically silicon nanocrystals are studied in a silicon oxide host matrix, which provides excellent surface passivation that ensures high radiative quantum efficiency. However other host matrices are of technological and scientific interest, particularly those that are ...

We study both theoretically and experimental1 the luminescence in non-intentionally but heavily p-doped GaAs quantum wells of 55 and 1501 width. At T=2K the PL spectra under cw excitation present an excitonic peak and a broad acceptor band. Time-resolved optical pumping of the acceptor line allows us to measure the free electron spin relaxation time. We have investigated its temperature depende...

We report detailed studies of the photoluminescence ~PL! properties of CdSe quantum dots ~QDs! grown on ZnSe and Zn0.97Be0.03Se by molecular-beam epitaxy. We performed steady-state and time-resolved PL measurements and observed that nonradiative processes dominate at room temperature ~RT! in the CdSe/Zn0.97Be0.03Se QD structures while these nonradiative processes do not dominate in the CdSe/ZnS...

We study the effects of bifunctional linker on the optical properties of ZnO nanocolumn-linker-CdSe quantum dots heterostructure. The CdSe quantum dots are anchored on the surface of ZnO nanocolumns through either aliphatic linker of 3-aminopropyl trimethoxysilane (APS) or aromatic linker of p-aminophenyl trimethoxysilane (APhS). X-ray photoelectron spectroscopy is used to confirm the bifunctio...

Bismuth-Gallium co-doped silica glass fiber preform was prepared from nano-porous silica xerogels using a conventional solution doping technique with a heterotrinuclear complex and subsequent sintering. Ga-connected optical Bismuth active center (BAC) was identified as the analogue of Al-connected BAC. Visible and infrared photoluminescence (PL) were investigated in a wide temperature range of ...