Papers by Keyword: MOVPE

Abstract: Optical transitions in the In0.050Ga0.950P0.975N0.025/GaP lattice-matched single quantum wells (SQWs) with different well widths (LZ = 1.6 - 6.4 nm) have been investigated by low-temperature photoluminescence (PL) and PL-excitation (PLE). PL spectra showed the strong visible emission from the samples which attracted to a variety of optoelectronic device applications such as light emitting and laser diodes. Comparing to the bulk film, the PL peak position and the fundamental absorption edge of PLE spectra exhibit blue-shift, which is corresponded to the quantum confinement effect by the well. Comparison between the absorption edge of PLE spectra and the finite square well calculation demonstrate that the effective bandgap energy of the InGaPN/GaP system is might be originated mainly from the N-related localized states.

Abstract: The use of an InGaAs buffer layer was applied to the growth of thick InxGa1-xAs1-yNy layers with higher In contents (x > 30%). In order to obtain the lattice-matched InGaAsN layer having the bandgap of 1.0 eV, the In0.2Ga0.8As was chosen. In this work, the In0.3Ga0.7As0.98N0.02 layers were successfully grown on closely lattice-matched In0.2Ga0.8As buffer layers (InGaAsN/InGaAs). Structural quality of such layers is discussed in comparison with those of the In0.3Ga0.7As0.98N0.02 layers grown directly on the GaAs substrate (InGaAsN/GaAs). Based on the results of transmission electron microscopy, the misfit dislocations (MDs), which are located near the InGaAsN/GaAs heteroepitaxial interface, are visible by their strain contrast. On the other hand, no generation of the MDs is evidenced in the InGaAsN layer grown on the In0.2Ga0.8As pseudosubstrate. Our results demonstrate that a reduction of misfit strain though the use of the pseudosubstrate made possible the growth of high In-content InGaAsN layers with higher crystal quality to extend the wavelength of InGaAsN material.

Abstract: The high quality GaAsN epitaxial films with the typical thickness of 150-200 nm and the N contents up to 5.5% were grown by MOVPE. The maximum N content of 2.75% at the growth temperature of 550 oC was enhanced to 5.1% at 500 oC and 5.5% at 450 oC. The lower growth temperature may efficiently suppress desorption of N atoms from the growing surface. The narrow high-resolution X-ray diffraction peaks and the clear Pendellösung fringes indicate that the GaAsN films with high uniformity and fairly flat interface were obtained. The 6K-photoluminescence (PL) peak energy of the GaAsN films was varied from 1.38 eV to 1.01 eV with increasing N content up to 2.75%, but no near-band-edge emission was observed in the higher-N-content films, indicating the increase of nonradiative recombination centers caused by the N-related lattice imperfections. Besides, after post growth thermal annealing at 650 oC for 2 min, PL spectrum shows that the near-band-edge emission as low as 0.97 eV (1.3 μm) have been achieved with the film of 5.1% N.

Abstract: Morphology and crystal-quality of InAs/In0.53Ga0.47As/InP quantum dots (QDs) grown by metal-organic vapor phase epitaxy (MOVPE) in N2 ambient using different growth modes have been studied. It is found that the morphology and crystal-quality of InAs QDs are dependant on the growth modes. After optimizing the dots’ growth modes, dots’ size dispersion and crystal-quality are both improved greatly, resulting in the enhancement factor of ∼ 2.9 in the photoluminescence (PL) peak-intensity from single QD. When the dots are buried, the dot size decrease compared with the free-standing dots due to the soon capping layer deposition during dots’ being buried. The thermal activation energy measured is comparable to the valence-band offset in the QD system calculated by 8 kp theory model. This indicates the PL quenching induced by the interface defects is suppressed due to the defect density lowering in the QDs grown by such optimized growth mode.