Influence of Growth Equipment Vibrations on Convective Processes during Doped Semiconductor Crystals Growth

In terrestrial experiments under conditions of weak convective currents, the effect of vibrations of growth equipment on the uniformity of semiconductor doped single crystals grown by the method of directional solidification was investigated. Studies are based on theoretical calculations and experimental results on the growth of gallium-doped germanium single crystals, during the crystallization of which convective processes, including those close to microgravity conditions, were simulated at different intensities. Measurement of inhomogeneity of dopant distribution over crystal length was carried out by microthermo-e.m.f. method developed and tested by the authors. (method of operational control), which avoids, among other things, the problem of the influence of the mobility of charge carriers on the measurement results. It is shown that vibrations of growth equipment lead to increased intensity of convective processes and, accordingly, to decrease of homogeneity of dopant distribution along the crystal length. It has been found that in order to obtain highly homogeneous semiconductor crystals, both in terrestrial and microgravity conditions, the crystallization process must be carried out by controlling the thermal field without mechanically moving the samples. The greatest significant influence of vibrations will be observed for microgravity conditions, where the microgravity sensitivity of doped melts to external influences greatly increases.