Relative lattice parameter measurement of submicron quaternary (InGaAsP) device structures grown on InP substrates

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Abstract
With x-ray diffraction techniques, it is possible to routinely measure lattice parameters to several parts in 104 for thin-film samples. However, measurements of lattice parameter changes for quaternary device structures several microns in width are not usually feasible with x-ray diffraction techniques. For this reason, transmission electron microscopy has been used to determine the position of higher-order Laue zone lines within convergent-beam electron diffraction patterns from thin foil cross sections of planar quaternary layers grown on InP substrates. A calibration curve has been generated which describes the position of higher-order Laue zone lines as a function of the lattice parameter determined from x-ray diffraction measurements. For the active quaternary region of an elecro-optical device structure, it is shown that ths calibration procedure may be sensitive to a relative change in lattice parameter as small as ±2 parts in 104.