Photoluminescence Properties Of In0 Research Articles

Photoluminescence spectra of 1 MeV electron beam irradiated In0.53Ga0.47As/InP quantum well and bulk materials

Minimizing the impact of radiation-induced degradation on optoelectronic devices is important in several applications. Satellites and other spacecraft that fly in near-earth orbits (below 3.8 earth radius) are extremely susceptible to radiation damage caused by the high flux of electrons trapped in the earth’s magnetosphere. Optoelectronic devices are particularly vulnerable to displacement damage caused by electrons and protons. Effects of 1 MeV electron beam irradiation on the photoluminescence properties of In0.53Ga0.47As/InP quantum well (QW) and bulk structures, which are grown by metal-organic vapor phase epitaxy, are investigated. Samples are irradiated at room temperature using an ELV-8II accelerator with 1 MeV electron at doses ranging from 5×1012 to 9×1014 cm-2, and a dose rate of 1.075×1010 cm-2·s-1. Photoluminescence measurements are made using a 532 nm laser for excitation and a cooled Ge detector with lock-in techniques for signal detection. Photoluminescence intensity of all the structures is degraded after irradiation, and its reduction increases with increasing total dose of irradiation. Electron beam irradiation causes a larger reduction in the photoluminescence intensity and carrier lifetime of the bulk than that of quantum well. Photoluminescence intensity of five-layer quantum wells degenerates to 9% that before irradiation as the fluence reaches 6×1014 cm-2. As the electron beams bombard into the sample, the destruction of the lattice integrity will cause the decrease in the number of excitons and intensity of photoluminescence. Electron beam irradiation introduces defects in the samples, increases the density of the nonradiative recombination centers, and results in the decrease of carrier mobility. In a quantum well structure, due to the two-dimensional confinement, the probability of carrier nonradiative recombination at radiation-induced defect centers will be reduced. The reduction of photoluminescence intensity in the bulk is severer than in the quantum well while the cross-sectional area which is sensitive to radiation is kept the same. The number of interface defects which are produced by electron irradiation will increase with the number of layers in quantum well and the heterojunction interface of quantum wells, so is the degration of photoluminescence intensity. The degration is mainly due to the increase of non-radiative centers in the samples. By comparing the different structures, the quantum well structure shows a better radiation resistance.

Application of photoluminescence spectroscopy to studies of In0.38Al0.62As/In0.38Ga0.62As/GaAs metamorphic nanoheterostructures

The results of studies of the surface morphology, electrical parameters, and photoluminescence properties of In0.38Al0.62As/In0.38Ga0.62As/In0.38Al0.62As metamorphic nanoheterostructures on GaAs substrates are reported. Some micron-sized defects oriented along the [011] and \([0\bar 11]\) directions and corresponding to regions of outcropping of stacking faults are detected on the surface of some heterostructures. The Hall mobility and optical properties of the samples correlate with the surface defect density. In the photoluminescence spectra, four emission bands corresponding to the recombination of charge carriers in the InGaAs quantum well (1–1.2 eV), the InAlAs metamorphic buffer (1.8–1.9 eV), the GaAs/AlGaAs superlattice at the buffer-substrate interface, and the GaAs substrate are detected. On the basis of experimentally recorded spectra and self-consistent calculations of the band diagram of the structures, the compositions of the alloy constituents of the heterostructures are established and the technological variations in the compositions in the series of samples are determined.

The Effect of Exciton Localization on the Photoluminescence Properties of In0.01Al0.11Ga0.88N

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Influence of V/III ratio on the structural and photoluminescence properties of In0.52AlAs/In0.53GaAs metamorphic high electron mobility transistor grown by molecular beam epitaxy

A series of metamorphic high electron mobility transistors (MMHEMTs) with different V/III flux ratios are grown on GaAs (001) substrates by molecular beam epitaxy (MBE). The samples are analysed by using atomic force microscopy (AFM), Hall measurement, and low temperature photoluminescence (PL). The optimum V/III ratio in a range from 15 to 60 for the growth of MMHEMTs is found to be around 40. At this ratio, the root mean square (RMS) roughness of the material is only 2.02 nm; a room-temperature mobility and a sheet electron density are obtained to be 10610.0cm2/(V·s) and 3.26 × 1012cm−2 respectively. These results are equivalent to those obtained for the same structure grown on InP substrate. There are two peaks in the PL spectrum of the structure, corresponding to two sub-energy levels of the In0.53Ga0.47As quantum well. It is found that the photoluminescence intensities of the two peaks vary with the V/III ratio, for which the reasons are discussed.

Growth and in situ annealing conditions for long-wavelength (Ga, In)(N, As)/GaAs lasers

The conjugated effect of growth temperature and in situ thermal annealing on the photoluminescence properties of In0.4Ga0.6As0.985N0.015/GaAs quantum wells (QWs) grown by molecular-beam epitaxy has been investigated. The interplay between growth temperature and annealing effects is such as the optimum growth temperature is not the same for as-grown and annealed samples. By using the combination of a low growth temperature and a high in situ annealing temperature, separate confinement heterostructure laser diodes with a single In0.4Ga0.6As1−xNx (x=0.015–0.021)/GaAs QW have been grown. The broad area devices emit from 1.34 to 1.44 μm at room temperature with a threshold current density of 1500–1755A∕cm2.

Structural and photoluminescence properties of In0.9(Ga/Al)0.1As self-assembled quantum dots on InP substrate

Self-assembled In0.9Ga0.1As, In0.9Al0.1As, and InAs quantum dots (QD) were fabricated in an InAlAs matrix lattice-matched to an InP substrate by molecular beam epitaxy. Preliminary characterizations were performed using transmission electron microscopy, photoluminescence, and reflection high-energy electron diffraction. Experimental results reveal clear differences in QD formation, size distribution, and luminescence between the InAs and In0.9(Ga/Al)0.1As samples, which show the potential of introducing ternary compositions to adjust the structural and optical properties of QDs on an InP substrate.

Determination of Al mole fraction for null conduction band offset in In0.5Ga0.5P/AlxGa1−xAs heterojunction by photoluminescence measurement

Photoluminescence properties of In0.5Ga0.5P/AlxGa1−xAs heterojunctions in both staggered and straddling band alignment regimes have been investigated. From the relation between the energies of below-band gap luminescence and Al compositions in the staggered band alignment regime, we determined the Al composition for null conduction band offset of the heterojunction as well as the conduction band offset value of In0.5Ga0.5P/GaAs heterojunction. Assuming the transitivity between the conduction band offset values, we also obtained the fraction of the band gap energy difference that is associated with the conduction band offset of an AlGaAs/GaAs heterojunction.