METHOD AND APPARATUS FOR GROWING INDIUM OXIDE (In203) SINGLE CRYSTALS AND INDIUM OXIDE (In203) SINGLE CRYSTAL

摘要

A method and apparatus for growing truly bulk In2O3 single crystals from the melt, as well as melt-grown bulk In2O3 single crystals are disclosed. The growth method comprises a controlled decomposition of initially non-conducting In2O3 starting material (23) during heating-up of a noble metal crucible (4) containing the In2O3 starting material (23) and thus increasing electrical conductivity of the In2O3 starting material with rising temperature, which is sufficient to couple with an electromagnetic field of an induction coil (6) through the crucible wall (24) around melting point of In2O3. Such coupling leads to an electromagnetic levitation of at least a portion (23.1) of the liquid In2O3 starting material with a neck (26) formation acting as crystallization seed. During cooling down of the noble metal crucible (4) with the liquid In2O3 starting material at least one bulk In2O3 single crystal (28.1, 28.2) is formed. We named this novel crystal growth method the “Levitation-Assisted Self-Seeding Crystal Growth Method”. The apparatus for growing bulk In2O3 single crystals from the melt comprises an inductively heated thermal system with a noble metal crucible (4) and evacuation passages (22, 22.1) for gaseous decomposition products of In2O3, while keeping very low temperature gradients. Various configurations of the induction coil (6), the noble metal crucible (4) and a lid (12) covering the crucible can be utilized to obtain very low temperature gradients, sufficient evacuation passages and a high levitation force. The electrical properties of the melt grown In2O3 single crystals can be modified in a wide range by at least one heat treatment in suitable atmospheres and appropriate temperatures.