STRAIN RELAXATION AND FORMATION OF SCREW DISLOCATIONS IN YBCO FILMS ON MGO SUBSTRATES

被引:18
作者
BAUER, M [1 ]
BAUDENBACHER, F [1 ]
KINDER, H [1 ]
机构
[1] TECH UNIV MUNICH,DEPT PHYS E10,D-85747 GARCHING,GERMANY
来源
PHYSICA C | 1995年 / 246卷 / 1-2期
关键词
D O I
10.1016/0921-4534(95)00128-X
中图分类号
O59 [应用物理学];
学科分类号
摘要
We have studied the growth of the first monolayers of YBa2Cu3O7 (YBCO) films on MgO substrates by reflection high-energy electron diffraction (RHEED), atomic force and scanning tunneling microscopy (AFM, STM) and scanning electron microscopy (SEM). Up to a nominal thickness of 1.5 nm we find island growth which is pseudomorphic to MgO. Between 1.5 and 4 nm there is a transition regime with relaxation of the lattice constant and coalescence of the islands. AFM and SEM show a coexistence of islands and contiguous patches while RHEED shows a broad distribution of lattice constants. On coalescence, we observe the formation of pairs of screw dislocations. We propose that the island growth results from the lattice misfit of 9% between YBCO and MgO, and that disorder arising during the relaxation of the strained islands is responsible for the early appearance of screw dislocations on MgO.
引用
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页码:113 / 118
页数:6
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