Melt growth of bulk Bi₂Te₃crystals with a natural p–n junction

Abstract

Single crystals of Bi2Te3 were grown from Bi–Te melts using the modified Bridgman method. It was shown for the first time that solidification of 61 and 62 mol.% Te melts provides a built-in p–n junction on the cleaved plane of as grown crystals without any post growth treatment. The formation of a p–n junction along the growth crystal was explained by Te segregation. Both p- and n-parts of the ingot have shown high carrier concentrations n ≈ p ≈ 1 × 1019 cm−3 and high carrier mobility ~104 cm2 V s−1 at 4 K. In the transition p–n region, Hall carrier concentration is decreased by two orders of magnitude as a result of intrinsic compensation of carriers.