Composition of AlGaAs

Abstract

Although the AlxGa1−xAs alloy system has been extensively investigated, there are still considerable uncertainties in measuring the value of x. Here a new AlxGa1−xAs calibration structure, grown by molecular beam epitaxy, has been used to establish unambiguous alloy compositions. Such “standard’’ AlxGa1−xAs layers were measured by high-resolution x-ray diffraction, photoluminescence, and Raman spectroscopy to determine the compositional variations of the measured physical parameters. The phenomenological equations derived from these measurements can now be used to establish the Al content of unknown alloys with confidence. In addition, the results show that Vegard’s law does not hold for the variation of the AlxGa1−xAs lattice constant with x. The small quadratic term has very important implications for a correct analysis of x-ray results.

MOVPE Self-Assembly and Physical Properties of Free-Standing III-V Nanowires

“…We assign this peak to the band-edge (excitonic) emission of the AlGaAs shell. This allows to determine the Al molar fraction in the alloy as x Al =0.34±0.01 (Pavesi & Guzzi, 1994;Wasilewski et al, 1997) in very good agreement with EDS Fig. 19.…”

III-V semiconductor waveguides for photonic functionality at 780 nm

“…Growth temperatures and flux ratios were optimized to achieve the designed composition with atomically smooth semiconductor interfaces, low defect density and low unintentional dopant concentrations. Lattice parameters were measured using X-ray diffraction (Philips X'Pert Materials Research Diffractometer) and used to verify Al composition based on a previously published model 4 .…”

“…In the III-V semiconductor system based on indium phosphide (InP), active and passive devices are integrated on wafer for commercial components at telecommunications wavelengths. However, for wavelengths shorter than 1 m an alternative alloy system must be used 4 .…”

A generalized Cahn–Hilliard equation incorporating geometrically linear elasticity

“…The resulting stress-strain relationship for the mixture is linear: this is Vegard's law. Vegard's law has been observed to fail in situations of great technological interest where the microstructure is known to be decisive for macroscopic properties, like, e.g., for Ga/As precipitates [56] and Ge/Si heterostructures [47]. An overview when Vegard's law fails is attempted in [28].…”