Adhesion-free Bridgman growth of AlSb

Abstract

AlSb crystals as a dual-carrier compound semiconductor have a great potential application for the room-temperature detectors, comparative to high-purity Ge and CdZnTe detectors. However, the single crystal growth of AlSb suffers from the high reactivity of Al, which causes strong adheres of the crystal to the crucible walls. In this work, an in-situ synthesis method was developed using a pBN crucible sealed in a quartz crucible. Meanwhile, the reaction of Al and Sb was settled under the melting point with two stages for solid reaction and liquid reaction in turn. The cycles of rapid directional solidification and refusion were implemented for homogenization. Bulk crystals of AlSb with large grain size 5 × 5 mm2 were obtained from the vertical Bridgman method. The results of the XRD and EDS test showed a single zinc blende structure phase with a nearly stoichiometric atomic ratio of 49.7: 50.3 (Al: Sb). AlN was observed between AlSb/BN interface during the crystals with normal overheating synthesis. The sticking mechanism was ascribed to the increase of the adhesion energy with PBN crucible after the production of AlN. The chemical reactivity of Al has been fully inhibited during the Bridgman growth of AlSb.