MAGNETIC FLOAT ZONE MICROGRAVITY CRYSTAL GROWTH/APPLICATION TO SILICON CARBIDE

AN INNOVATIVE TECHNIQUE IS PROPOSED TO IMPROVE THE QUALITY OF ELECTRONIC MATERIALS DURING A FLOATING ZONE CRYSTAL GROWTH PROCESS UNDER MICROGRAVITY CONDITIONS BY APPLYING AN AXIAL DC MAGNETIC FIELD TO A FLOATING ZONE. THE APPLIED MAGNETIC FIELD IS TO SUPPRESS THE UNDESIRABLE CONVECTION CAUSED BY SURFACE TENSION DUE TO TEMPERATURE AND DOPANT VARIATIONS ALONG THE FREE SURFACE. THE CONCEPT WILL BE VERIFIED THROUGH NUMERICAL SIMULATIONS OF THE MAGNETODYNAMICS AND HEAT TRANSFER CHARACTERISTICS OF A REALISTIC FLOATING ZONE SYSTEM. A PARAMETRIC STUDY WILL BE PERFORMED IN PHASE II TO COMPILE A KNOWLEDGE BASE WHICH WILL1) SUGGEST PARAMETERS FOR DESIGNING A COMMERCIAL APPARATUS AND 2) FACILITATE AUTOMATED ON-LINE FEEDBACK CONTROL OF THE GROWING PROCESS. THE ENTIRE SYSTEM WILL BE SELF-CONTAINED AND REQUIRE MINIMUM HUMAN CONTROL. REALISTIC PARAMETERS WILL BE USED FOR SIMULATION OF TITANIUM CARBIDE CRYSTAL GROWTH FOR USE AS SUBSTRATES IN THE EPITAXIAL GROWTH OF SILICON CARBIDE. THE DESIGN STUDIES OF PHASE II WOULD BE CARRIED OUT FOR BOTH EARTH GRAVITY AND ORBITAL MICROGRAVITY CONDITIONS, AND AN ORBITAL REACTOR WOULD ALSO BE DESIGNED.