Microstructure and Thermoelectric Properties of p-Type Bi_(0.5)Sb_(1.5)Te_3 and n-Type Bi_2Te_(2.7)Se_(0.3) Films Deposited by Pulsed Laser Ablation

摘要

Thin films of p-type Bi_(05)Sb_(1.5)Te_3, n-type Bi_2Te_(2.7)Se_(0.3) and n-type with SbI_3 doping were deposited on mica substrates using Nd-YAG pulsed laser ablation at temperatures ranging from 300°C to 500°C. These films were characterized using X-ray diffraction, SEM and TEM. X-ray mapping and EDS were used to determine the composition. The films showed uniform thickness and high crystalline quality with a preferred (00n) alignment with the substrates. The film quality in terms of composition and crystal perfection is studied as a function of growth temperature. It was found that films deposited at 350°C gave improved crystallinity and thermoelectric characteristics. The Seebeck coefficient, electrical resistivity and Hall mobility were measured as a function of temperature and compared with the measurements on the bulk. Correlation of thermoelectric properties with microstructure is discussed.