Inclusions in LEC-grown Si GaAs single crystals

The relationship between surface flaws and three-dimensional defects in LEC-grown SI GaAs was investigated by laser scattering tomography (LST), Surfscan mappings and analytical REM. Occasionally found singular scatterers (SSs)-the general features of which are clearly different from decoration and matrix As-precipitates-were analysed in depth in relation to the crystal growth conditions. It is shown that these defects cause outsized light scattering defects on the surface of finally polished wafers known as area counts. It has been concluded that the reason for these area counts are particles of foreign phases captured by the moving solid/liquid interface. A reasonable agreement between experimental results and the conclusions of the “capture theory” of Chernov et al. has been ascertained. From this understanding of area counts measures were derived to surely avoid inclusions during LEC growth of GaAs single crystals.