Strain relaxation and surface roughness of InxAl1−xAs graded buffer layers grown on InP for 6.05Å applications

Abstract

Articles you may be interested inImpact of varying buffer thickness generated strain and threading dislocations on the formation of plasma assisted MBE grown ultra-thin AlGaN/GaN heterostructure on silicon AIP Advances 5, 057149 (2015); 10.1063/1.4921757 Structural, morphological, and defect properties of metamorphic In0.7Ga0.3As/GaAs0.35Sb0.65 p-type tunnel field effect transistor structure grown by molecular beam epitaxy J. Vac. Sci. Technol. B 31, 041203 (2013); 10.1116/1.4812793 μm emission from type-I quantum wells grown on InAsxP1−x/InP metamorphic graded buffersStrain relaxation properties of InAs y P 1 − y metamorphic materials grown on InP substrates Impact of arsenic species ( As 2 ∕ As 4 ) on the relaxation and morphology of step-graded In As x P 1 − x on InP substrates J.In this study, metamorphic compositionally graded In x Al 1−x As layers grown on InP by molecular beam epitaxy with a final indium mole fraction of x = 1.0 ͑6.05 Å͒ are investigated. To examine the effects of relative growth temperature on strain relaxation and surface morphology at different stages of the buffer layer growth, a series of samples was produced with the indium mole fraction graded from x = 0.52 to x = 0.64, 0.79, and 1.0 with a constant grading rate. The high misfit dislocation velocity in this system allows the grading to be accomplished with a thin layer ͑ϳ1 m͒, complete strain relaxation and low threading dislocation densities. The evolution of the strain relaxation, threading dislocation density, and surface morphology were evaluated by triple axis x-ray diffraction, transmission electron microscopy (TEM), etch pit density (EPD), and atomic force microscopy. Higher growth temperature led to threading densities as low as 10 6 cm −2 , as measured by plan-view TEM and EPD. The final surface roughness was controlled by the growth temperature of a constant composition cap layer.

InAs on Insulator by Hydrogen Implantation and Exfoliation

“…The graded buffer layer is graded from the InP lattice matched composition to InAs over 1 µm resulting in a threading dislocation density of 5 x 10 6 cm -2 in the InAs cap. [6] Figure 1 shows these structures and the layer transfer sequence. Before further processing the graded buffer layer structure is subject to a chemical mechanical polishing (CMP) step to eliminate the cross-hatch surface morphology and reduce the RMS surface roughness below 1 nm in order to promote wafer bonding.…”

“…Graded buffer layers are often used to achieve low threading dislocation density layers of some specific alloy composition (or lattice parameter) by slowly changing the graded rate over the growth direction. [5,6] Unfortunately, the graded layer, typically a ternary or quaternary alloy, can be very thick leading to poor heat dissipation and device isolation. However, wafer bonding and hydrogen exfoliation techniques can be used to transfer these metamorphic layers directly onto a semiinsulating substrate.…”

X-Ray and Electron Diffraction for Epitaxial Structures

“…Compositions with high dislocation glide velocities and growth at high temperatures both help assure more effective relaxation and the lack of dislocation multiplication events [46,47]. In this form, the layer composition and lattice parameter are both intentionally changing as a function of depth; the goal is to produce interfaces with long misfit segments and the absence of threading dislocation multiplication sites.…”

High vertical yield InP nanowire growth on Si(111) using a thin buffer layer

“…This temperature dependent behaviour can also be attributed to the surface diffusion of the adatoms. When the growth temperature is high, adatoms can migrate to an energetically favourable site in the underlying dislocation network [13,39], which would be a newly nucleated relaxed terrace at an unstrained location of the initial layer [40]. Continued growth on the facets of these terraces leads to the pyramid-like structures.…”