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

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.