Synthesis of the 2D Ternary Topological Insulator Bi_2-xSb_xSe₃ with a Low Carrier Concentration and Ultrahigh Carrier Mobility

Highcarrier concentration and low mobility in Bi2Se3 hide thetopological surface states (TSS). In the 2D ternary topological insulator (TI) Bi2-xSbxSe3,compensatory Sb doping regulates the carrier concentration and mobility withambipolar performance, together with the ultrathin thickness; these factorsmake the TSS in the 2D ternary TI Bi2-xSbxSe3 more observable. Here, a chemical vapor deposition (CVD) method is provided for synthesizing ultrathin Sb-doped Bi2Se3 nanoplates with dimensions of 2-126 nm in thickness, 3-100 mu m in lateral size, and an average Sb doping ranging from 0.15 <= x <= 0.75. Bi2-xSbxSe3 field effect transistors and Hall devices are manufactured to determine the carrier concentration and mobility of the obtained Bi2-xSbxSe3 nanoplates. These findings demonstrate that the 2D carrier concentration for Bi2-xSbxSe3 nanoplates can decrease up to 1.6 x 10(12) cm(-2). Furthermore, field-effect mobility and Hall mobility of up to 3411 cm(2) V(-1)s(-1) and 6462 cm(2) V-1 s(-1), respectively, are realized. A strong ambipolar field effect is found in low-carrier-density Bi2-xSbxSe3 nanoplates, proving that these nanostructures may be freely controlled in terms of carrier type and concentration. The synthesis of high-quality Bi2-xSbxSe3 nanoplates with low-carrier concentration and high-mobility provides a platform for investigating TI characteristics more clearly.