Layered Cobalt-based Thermoelectric Thin Films And Their Laser Induced Thermoelectric Voltage Effect

In this paper,Bi_2-xPb_xSr₂Co₂O_y(BPSCO)and Ca₃Co₄O₉(CCO)were investigated. BPSCO and CCO polycrystalline were papered by using solid-state reaction method. BPSCO and CCO thin films were prepared on sapphire substrates by using pulse laser deposition technology whose LITV signal were measured and related physical mechanism were discussed.BPSCO compounds were successfully prepared by using solid state reaction method. the result show that BPSCO polycrystalline were single phase,there is no unexpected phase. all of them were preferentially oriented to(001)plane.BPSCO thin films were prepared on vicinal-cut sapphire substrates whose titled angle is 0,5 and 10 respectively.X-ray diffraction was used to determine the micro-structure and orientation of BPSCO thin films.The results show that BPSCO thin films were preferentially oriented to(001)plane along c-axis,and exhibited good crystallinity.LITV signal show that with the increase in doping,the peak voltage increases first and then decreases,when doping is 0.4,the peak voltage reaches the highest value.The LITV peak voltage of thin films exponential decreases with the increasing of thickness of thin films.CCO compound was successfully synthesized by using solid-state reaction method. CCO polycrystalline has single phase,and preferentially oriented alone c-axis.PLD technology was used for preparing CCO thin films on vicinal-cut sapphire substrates.The growth condition of CCO thin films was systemic investigated.CCO thin films were prepared in different partial oxygen pressure and thickness,and then LITV signal were measured,the impact of partial oxygen and thickness on thin films were discussed.The result show that when temperature of substrate was 800,CCO thin films has good crystallinity,and grow alone(001)oriented in c-axis.When the partial oxygen increased, thin films expitaxial grow alone c-axis in 100 Pa.when the partial oxygen pressure reached 100 Pa,the thin film showed the best crystallinity while the crystallinity showed the worst in 200 Pa oxygen pressure.When oxygen pressure was 200 Pa,the LITV signal reached the highest value than other oxygen pressure.LITV decrease with the increase of thickness of thin films.