Microwave Induced Plasma Synthesis and Characterization of Rice Kernel-Like Bi₂Te₃ Crystals

Microwave induced plasma heating for solid-state synthesis of Bi₂Te₃ rice kernel-like crystals is reported. Different powers of irradiated microwave plasma and lengths of time (450 W, 60 min; 600 W, 30 min; and 900 W, 20 min) were used to synthesize pure products in 4.3±1 kPa absolute pressure of argon. Phase and structure characterizations revealed the presence of Bi₂Te₃ crystals with uniform shape of rice kernels in the size of 1 μm long and 250–300 nm wide at the middle, including their four Raman active modes of E ¹ _g , A ¹ _1g , E ² _g and A ² _1g at 35.19, 60.35, 100.58 and 130.37 cm⁻¹, respectively. Growth of a rice kernel-like Bi₂Te₃ crystal was in the [110] direction, including the direct energy gap of 0.56 eV.