退火氧压对YBa2Cu3O7-x薄膜中的激光感生热电电压效应的影响  

Influence of annealing oxygen pressure on the laser-induced thermoelectric voltage effect in YBa_2Cu_3O_(7-x) thin films

作　　者：熊飞[1] 张辉[1] 李洪山[1] 张鹏翔[1] 蒋最敏[2] 

机构地区：[1]昆明理工大学光电子新材料研究所,昆明650051 [2]复旦大学应用表面物理国家重点实验室,上海200433

出　　处：《物理学报》2008年第8期5237-5243,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10274026);云南省自然科学基金(批准号:YKS199907022)资助的课题~~

摘　　要：测量了在不同氧压下退火生长的YBa2Cu3O7-x(YBCO)薄膜中的激光感生热电电压(LITV)信号,发现随退火氧压的增大可使LITV信号的峰值有2—4倍的增强,并且变化趋势与薄膜热电势的各向异性随氧含量的变化规律相同.波长在473—808nm范围内的连续激光辐照,在5000Pa的氧压下退火生长的YBCO薄膜中探测到的LITV信号最大;而紫外脉冲激光辐照时,LITV信号的最大值出现在退火氧压为105Pa的薄膜中.LITV信号的光响应时间随退火氧压的增大而减小,理论分析表明,这一结果是由于退火氧压的提高导致薄膜材料的热扩散系数增大所致.在退火氧压为5000Pa的YBCO薄膜中探测到响应最快的LITV信号,对紫外脉冲激光的响应时间为78ns,并且信号的上升时间只有29ns,与激光的脉冲宽度(约为28ns)相当.The laser-induced thermoelectric voltage（LITV） signals were measured in the YBa2Cu3O7-x（YBCO） films annealed under different oxygen pressure.It was found that the detected LITV signals were enhanced 2—4 times with the increasing of annealing oxygen pressure.The effect can be explained by the dependence of thermoelectric anisotropy on the oxygen content in YBCO.When the films were illuminated by continuous lasers in the wavelength range of 473—808nm,the measured signals in the films annealed under 5000？Pa oxygen pressure were larger than those in other films.Meanwhile,pulse ultraviolet laser illumination produced the largest signal in the films annealed under oxygen pressure of 105Pa.The response time of LITV signals was observed to become shorter with the increasing of annealing oxygen pressure,which was shown to have resulted from the increasing of thermal conductivity theoretically.The films annealed under 5000Pa oxygen pressure had the fastest response to the pulsed ultraviolet laser.The response time was 70ns and the rise time of 29ns was comparable to the duration of the applied laser pulse（about 28ns）.

关 键 词：YBa2Cu3O7-x薄膜 激光感生热电电压 各向异性的Seebeck系数 氧含量 

分 类 号：O484[理学—固体物理]