The GexSi1-x/Si superlattice with 23 periods was grown by molecular beam epitaxy. The X-ray diffraction pattern was measured using a computer-controlled X-ray diffractometer with Cu Ka radiation. Interference peaks due to the superlattice structure were observed up to the 13th order. The superlattice period and the Ge average composition can be determined from the interference peak angles based on a modified Bragg's law, which was derived by including the X-ray refraction at the superlattice surface and interfaces. The structural parameter can be determined by analyzing the X-ray diffraction pattern based on the optical multilayer reflection theory. The intensity ratio of the 2nd peak to the 1st peak is quite sensitive to the variation of the thickness ratio of the two components. By comparing the calculated value of I2/I1 to the experiment, we can determine the thicknesses of Si and GexSi1-x layers, and finallv x. The diffraction pattern calculated using the optical mutilayer reflection theory was in accordance with the measured ones.

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A study of defects in silicon produced by hightemperature electron irradiation was carried out. It was found that the introduction rate of defect increased with the temperature at which the samples were irradiated by electron. After the temperature reached an "extreme" value Tm, the introduction rate of defect began to decrease. The Tm value was related to the annealing activation energy of defect. It was also found that the density of E3 (Ec-0.36 eV) defects greatly increased in hightemperature electron irradiation. When electron irradiation was carried out at 330℃, the density of E3 defects was about 6 times as large as that at room temperature. The possible structure of the E3 defect is multivacancy-oxygen complex.

A theoretical and experimental study of intersubband absorption in p-type GexSi1-x/Si multiple quantum wells are presented,the calculations are performed with envelop-function approach,with full inclusion of the degeneracy and warping of the three topmost bulk valence bands described by the strain-dependent Luttinger-Kohn Hamiltonian.The Hartree potential and the exchange correlation interaction are taken into account in a self-consistent manner.And finally the absorption spectra is calculated.We contribute some absoptions observed with normal incident unpolarized infra-beam to the band-mixing of heavy,light and split-off bands in GexSi1-x/Si quantum wells.