The study of microstructure in iron- and sulphur-doped InP crystals by means of HREM and computer simulation

The microstructures in iron- and sulphur-doped InP crystals were studied using both electron microscopy and electron diffraction. A modulated structure has been found in S-doped InP crystal, where the commensurate modulations corresponded to periodicities of 0.68 nm and 0.7 nm in real space were related to the reflections of the cubic lattice in (111) and (113) directions; they were indexed as q₁₁₁*=1/2(a*+b*+c*) and q*113=1/4(-a*-b*+3c*), respectively. Single atomic layers of iron precipitate were observed, with preferred orientations along which precipitates are formed. Simulated calculations by means of the dynamical theory of electron diffraction using models for the precipitate structure were in good agreement with the authors experimental results. The relation between the modulated structure and the precipitates is also discussed.