Study of the optical and structural properties of multi quantum well structures grown on high-index surfaces
The MOVPE overgrowth of high [01@?1]-oriented ridges confined at sides by facets related to {n11} crystallographic planes is reported. We studied the influence of the side tilt on the thickness of the AlGaAs and GaAs epitaxial layers grown under the condition of the kinetic growth mode. The multi quantum well (MQW) structures were prepared on the sides of ridges tilted at 54.7^o, 45^o and 30^o to (100). The sidewall surface morphologies before and after epitaxial growth were evaluated and compared. We observed no tendency towards planarization towards a neighbouring high-index crystallographic plane, such as (211) and (311). We also showed that the quantum wells of the MQW structure make a smooth transition over the edge between the top surface and the facet as both AlGaAs and GaAs grew at similar rates on the surfaces.
OMVPE fabrication of continuous transitions between GaAs/AlGaAs quantum wells and V-groove quantum wires
The fabrication of defect-free and continuous transitions between AlGaAs/GaAs quantum wells (QWs) and quantum wires (QWRs) using organo-metallic vapor phase epitaxy on variable-width V-grooved substrates is demonstrated. The basic idea of our approach is developed using a Monte-Carlo simulation of the self-limiting growth on tapered grooves. A detailed surface and cross-sectional atomic force microscopy study reveals the high quality of the resulting coupled quantum structures. In particular, we demonstrate the efficient control, brought about by this experimental technique, on the well-wire transitions.
Theoretical Comparison of (111) and (100) GaAs/AlGaAs p-Type Quantum Well Infrared Photodetectors
Intersubband absorptions in p-type GaAs/Al0.3Ga0.7As quantum wells (QWs) grown on (111) substrates are theoretically investigated using the multiband effective mass model. Because of the stronger band mixing of (100) QW, the peak absorption coefficient of the (100) QW is about twice as large as that of (111) QW. Nevertheless, the detectivity of (111) Quantum Well Infrared Photodetector (QWIP) is found to be ?30% larger than that of (100) QWIP because of the smaller dark current of (111) QWIP. This is due to the smaller heavy-hole confinement energy in (111) QW.