Contributions to the development of crystal growth technologies

Abstract

An overview of selected contributions to the development of crystal growth technology of the Laudise Prize awardee 2023 is presented. First some results on shaped crystal growth are given, such as layers with eutectic periodic structures, casting of high-resistivity CdTe sheets, growth of in situ core doped laser rods by double die EFG, and Czochralski growth of Si crystals with rectangular cross section. Then the correlation between melt structure and quality of II-VI crystals showing high bond ionicity is discussed. The importance of marked melt overheating for growth of high-quality CdTe and (Cd,Zn)Te crystals is derived. Also the in situ stoichiometry control for reducing intrinsic point defects, precipitates and inclusions is demonstrated by the examples of Bridgman and VGF CdTe growth with Cd extra source and vapor pressure controlled Czochralski method of 6 inch GaAs crystals. Next, the reason and general appearance of dislocation cell patterns in all growing thermomechanical stressed crystals and their possible prevention are explained. The contribution of point defect diffusion for dislocation climb at high temperatures to form globular cells is underlined. Finally, melt growth experiments under travelling magnetic field (TMF) generated in coil-shaped heater-magnet modules around the crucibles are discussed. The importance of global numeric modeling for optimization the TMF convection mode in the melt is accentuated. It is shown that the growing interface can be levelled, the solution flux at vertical liquid phase epitaxy can be homogenized, and the IR transmission and minority carrier live time in 640 kg mc-Si ingots for photovoltaics can be markedly enhanced and homogenize by such external field application. The close cooperation between academics, engineers and industry is particularly emphasized.