DENSITY OF AMORPHOUS SIXGE1-X ALLOYS PREPARED BY HIGH-ENERGY ION-IMPLANTATION

The atomic density of amorphous SixGe1-x alloys (0 less than or equal to x less than or equal to 1), has been measured. The amorphous alloys were made by high-ion-energy implantation into monocrystalline SixGe1 -x layers, deposited epitaxially on silicon substrates. During the bom bardments, a steel contact mask was used to create alternating lines o f amorphous and crystalline material. The ratio between the densities of crystalline and amorphous alloys was measured with 0.1-0.2% accurac y using surface profilometry and Rutherford backscattering spectrometr y in conjunction with channelling. Amorphous pure elements and alloys are less dense by 1.5-2.1% than the crystalline pure elements and allo ys. By comparing both the amorphous and crystalline densities with Veg ard's law, it is found that this law underestimates the a-SixGe1-x den sities by the same amount as those of c-SixGe1-x.