SrTiO3(001)衬底上单层FeSe超导薄膜的分子束外延生长
Molecular b eam epitaxy of single unit-cell FeSe superconducting films on SrTiO3(001)
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摘要: 在以前工作的基础上,进一步研究了SrTiO3(001)(STO)衬底上单层FeSe超导薄膜的分子束外延生长。首先,通过去离子水刻蚀、盐酸溶液腐蚀和纯氧气氛中退火等步骤,获得台阶有序、具有单一TiO2终止的原子级平整表面的STO衬底,这是前提条件。这个过程中酸的选择和退火过程中氧的流量是最为关键的因素。其次,在FeSe薄膜的分子束外延生长中,选择适当的Fe源和Se源束流以及衬底温度是关键因素。如选择适当,生长模式为step-flow生长,这时得到的FeSe薄膜将是原子级平整的。最后一步为退火,这个过程会增强FeSe薄膜结晶性以及它与SrTiO3衬底间的结合强度。
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关键词:
- SrTiO3(001) /
- 单层FeSe薄膜 /
- 高温超导 /
- 分子束外延
Abstract: Based on our previous work, we have systematically investigated the molecular beam epitaxy growth of single unit-cell FeSe films on SrTiO3(001) substrates and studied the surface morphology by scanning tunneling microscopy. We found that there are three key steps to obtain large-scale uniform one unit-cell superconducting FeSe films. First, the STO(001) substrates should be treated by HCl etching and thermal annealing under oxygen flux so that a specific TiO2-terminated STO(001) surface with well-defined step-terrace structure could be obtained. Second, the Fe and Se fluxes and substrate temperature have to be controlled delicately. At last, post-growth annealing is also critical, which can remove extra Se adatoms, and more importantly facilitate the necessary electron transfer for superconductivity transition. -
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