ELECTRICAL AND OPTICAL-PROPERTIES OF TL-DOPED BI2TE3 CRYSTALS

Modified Bridgman method was used to grow Bi2Te3 single crystals doped with thallium in the concentration range of 10(17)-10(18) atoms/cm(3) . Experimental values of the electrical conductivity and Hall constant indicate that the introduction of Tl atoms into the lattice of p-Bi2T e3 leads to a pronounced suppression of the concentration of holes. Al so, it follows from the decrease of the absorption coefficient in the IR region that the concentration of holes decreases with increasing co ntent of Tl atoms built into the lattice, Analysis of possible point d efects and comparison of the structure of Bi2Te3 and TlBiTe2 suggest a probable explanation that the mentioned effect could be due to the su bstitution of the (Te-Bi-Te-Tl-V-Te(..)) + 2e' fragment for the Te-1-B i-Te-2-Bi-Te-1 five-layer stack in me Bi2Te3 structure.