High‐quality single‐crystal Nb films and influences of substrates on the epitaxial growth
High‐quality single‐crystal Nb films and influences of substrates on the epitaxial growth
复制标题
高质量单晶铌薄膜及衬底对外延生长的影响
DOI：
10.1063/1.337323
复制
发表时间：
1986
影响因子：
3.2
通讯作者：
Y. Sawada
中科院分区：
文献类型：
--
作者：
G. Oya;M. Koishi;Y. Sawada
用电子束蒸发技术在单晶蓝宝石(∼-Al_2O_3)和氧化镁(∼)衬底上用电子束蒸发技术外延生长了超导转变温度T_c=9.3K，电阻比R_(300)/R_(10)高达∼_(200)的高纯单晶Nb薄膜(厚度为 2000A)，超导转变温度T_c=9.3K，电阻比R_(300/R_(10))高达_(200)。在蓝宝石(1102)衬底上获得了最高质量的单晶Nb薄膜(最大T_c为9.45K，最大R_(300/R_(10))为199)，其热膨胀系数与Nb的热膨胀系数非常接近，并且与Nb的晶格失配很小。发现在热膨胀系数与Nb相差较大的衬底上沉积Nb单晶薄膜会降低单晶Nb薄膜的质量，这是因为在冷却后的薄膜中产生了内应变和晶格缺陷。
Highly pure single‐crystal Nb films (thickness, ∼2000 A) with high superconducting transition temperatures Tc of ∼9.3 K and high resistance ratios R300/R10 up to ∼200 are successfully grown epitaxially on single‐crystal sapphire (α‐Al2O3) and MgO substrates at ∼500–∼700 °C by using an electron‐beam evaporation technique. The most high‐quality single‐crystal Nb film (with the maximum Tc of 9.45 K and the maximum R300/R10 of 199) is obtained on a sapphire (1102) substrate, which has a thermal expansion coefficient very close to that of Nb as well as a small lattice misfit to Nb. The quality of obtained single‐crystal Nb films is found to be lowered by the deposition of the films on substrates with thermal expansion coefficients different far from that of Nb because of the production of internal strains and lattice defects in the films cooled down.