BETA-SILICON CARBIDE AND ITS POTENTIAL FOR DEVICES

摘要

During this contract period, nitrogen was definitely established as the principal impurity in solution-grown p-silicon carbide crystals. To reduce the nitrogen level in these crystals, chemical and high vacuum bakeout treatments were applied to (1) graphite crucible materials, (2) graphite structural elements in the crystal growing furnace, (3) the silicon solvent, and (4) the inert gas supplied to the furnace during crystal growth. Lowering of nitrogen (and metallic impurity) contents was monitored directly with each process modification until the limits of detection were exceeded. Subsequently, crystal resistivity was employed as a purity indicator.