Comparison of Different Processing Routes for the Synthesis of Semiconducting AlSb

Abstract

AlSb is a low-cost, high-band-gap semiconducting material, yet largely limited in its potential due to difficulty in the synthesis of single-phase AlSb. The present work compares different processing routes in their potency to produce bulk and nanocrystalline AlSb. Vacuum arc melting has been successfully employed, for the first time, to synthesize single-phase bulk AlSb. Owing to high vapor pressure of Sb, an optimum amount of excess Sb (3%) needs to be added to achieve single-phase line compound AlSb. Two methods, viz. mechanical alloying of elemental powders and mechanical milling of cast alloy, have been used to synthesize nanocrystalline AlSb. Nanocrystalline AlSb could be produced after ball milling the cast alloy; however, prolonged milling results in the appearance of Sb along with a non-stoichiometric Al-Sb-O oxide. Mechanical alloying of Al and Sb does not lead to appearance of single-phase AlSb, and the mixture largely consists of starting material and amorphous products. Therefore, the effectiveness of a synthesis route in producing single-phase AlSb is governed by the tendency of oxygen pickup during the processing.