The least number of pairs of layers needed for observation of satellite-structured X-ray diffraction in superlattices. Measurements and calculations of elastic stresses in alternate layers of superlattices

The AlxGa1-xAs/GaAs.../GaAs(001) superlattices with the period T≥100 nm are studied by X-ray diffractometry and topography. It is shown that, to observe satellite peaks essential for identification and measurements of the parameters for superlattices on single-crystal substrates in the X-ray diffraction spectra, it is sufficient to grow only two pairs of alternate AlxGa1-xAs/GaAs layers. The X-ray diffraction technique allows for the observation and measurements of the parameters for elastically and plastically strained superlattices. The theoretical basis is presented, and the elastic stresses in the alternate layers of the AlxGa1-xAs/GaAs.../GaAs(001) superlattices are calculated. The results are as follows: for N1 = 10 pairs of layers, the stresses are σ2N = 4.37 x 105 Pa and σ2N-1 = -4.37 x 107 Pa; for N2 = 2 pairs of layers, 2σ2N = 6.16 x 106 Pa and σ2N-1 = -2.8 x 107 Pa. The stress σ2N-1 = -4.37 x 107 Pa induces plastic deformation in the allo layers of the superlattice with the number of pairs of layers N1 = 10.