n-Type (Bi 2 Te 3 ) 0.93 (Bi 2 Se 3 ) 0.07 thermoelectric materials doped with various content of TeI 4 (0, 0.05, 0.10, 0.13, and 0.15wt.%) have been fabricated through the zone melting method. Electrical conductivity (σ), Seebeck coefficient (α) and thermal conductivity (κ) were measured along the crystal growth direction in the temperature range of 300–500K. The influence of the variations of TeI 4 content on thermoelectric properties was studied. The undoped (Bi 2 Te 3 ) 0.93 (Bi 2 Se 3 ) 0.07 exhibited p-type conduction and it translated to n-type when TeI 4 was doped. The increase of TeI 4 content increased the carrier concentration and thus resulted in an increase of σ and a decrease of |α|. The maximum figure of merit ZT (ZT=α 2 σT/κ) of the zone-melted crystals in the direction parallel to the growth direction showed a value of 0.90 for the sample containing 0.10wt.% TeI 4 .