TlBaCaCuO-(2212) thin films on lanthanum aluminate and sapphire substrates for microwave filters
TlBaCaCuO-(2212) thin films on lanthanum aluminate and sapphire substrates for microwave filters
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DOI：
10.1088/0953-2048/14/4/305
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发表时间：
2001-04
影响因子：
3.6
通讯作者：
H. Schneidewind;M. Manzel;G. Bruchlos;K. Kirsch
中科院分区：
文献类型：
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作者：
H. Schneidewind;M. Manzel;G. Bruchlos;K. Kirsch
在2英寸铝酸镧衬底和双面涂覆CeO_2的R切蓝宝石衬底上制备了高质量的Tl_2Ba_2CaCu_2O_8微波滤波器薄膜。在铝酸镧衬底的情况下，薄膜的厚度高达1 µm。在CeO 2缓冲的蓝宝石衬底上，可以制备厚达400 nm的无裂纹超导膜。对于两种衬底材料，在77 K时，都达到了Jc>2×106 A·cm ~（-2）的高临界电流密度。在低场情况下，在5.6 GHz和77 K下测得的微波表面电阻Rs低于100 µΩ，与YBa 2Cu 3 O 7-x材料制成的最佳薄膜相当。该膜能够耐受对应于BRF>2 mT的磁场幅度的高微波功率水平。临界温度超过102 K。即使经过几次热循环，这种优异的性能也能保持。该薄膜用于生产C波段的四极带通滤波器，其在高达约85 K的温度下的传输特性中没有任何可检测的损失。这是第一次在蓝宝石上制备大面积（2英寸）双面Tl_2Ba_2CaCu_2O_8薄膜，具有优异的临界电流密度和低的表面电阻。
High-quality Tl2Ba2CaCu2O8 films for microwave filter application are prepared on both sides of 2 inch lanthanum aluminate substrates as well as on double-sided CeO2 coated r-cut sapphire substrates. The films have thicknesses as high as 1 µm in the case of lanthanum aluminate substrates. On CeO2 buffered sapphire substrates it is possible to prepare crack-free superconducting films as thick as 400 nm. For both substrate materials we reach high critical current densities of Jc>2×106 A cm-2 at 77 K. The microwave surface resistances Rs were measured to fall short of 100 µΩ at 5.6 GHz and 77 K in the low-field case, comparable to the best films made of YBa2Cu3O7-x material. The films were able to tolerate high microwave power levels corresponding to magnetic field amplitudes of BRF>2 mT. The critical temperature exceeds 102 K. This excellent performance is maintained even after several thermal cycles. The films were used to produce four-pole band-pass filters for the C-band which were operated without any detectable loss in their transfer characteristics up to temperatures of about 85 K. This is the first time that large area (2 inch) double-sided Tl2Ba2CaCu2O8 films have been prepared on sapphire with excellent critical current density in conjunction with low surface resistance.