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.
QWIP structures prepared on wet‐etched non‐planar GaAs
We studied the possibility to prepare a multi quantum well (MQW) structure on a non-planar wet-etched object patterned in (100) GaAs semi-insulating substrate with the aim to develop a QWIP with new normal incidence geometry. A H3PO4-based etching solution was used to pattern GaAs substrate through a strip mask pattern. This yielded 20 µm-deep [0-11]-oriented ridges with good sidewall surface morphology, which was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The non-planar objects were MOCVD (Metalorganic Chemical Vapor Deposition) overgrown with a GaAs/Al0.3Ga0.7As MQW structure including bottom and top n-doped GaAs layers. AFM and SEM study and cross-sectional transmition electron microscopy (TEM) were employed to characterize properties of the heterostructure. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimising the growth of pyramidal GaAs microstructures on pre-patterned GaAs(001) substrates
Abstract Facet formation during the growth by molecular beam epitaxy of GaAs microstructures on pre-patterned GaAs(0 0 1) substrates has been investigated by secondary electron microscopy and atomic force microscopy. The effects of the growth conditions have been studied for structures formed on both stripe and square based mesas. In all cases {1 1 0} facets are formed suggesting that kinetics plays a key role in determining the shape of the resulting microstructure. We show that by optimising the growth conditions it is possible to produce high quality pyramidal microstructures that appear to have the appropriate characteristics for application as a corner cube mirror in optoelectronic device applications.