A surfactant-mediated relaxed Si0.5Ge0.5 graded layer with a very low threading dislocation density and smooth surface

被引:59
作者
Liu, JL [1 ]
Moore, CD
U'Ren, GD
Luo, YH
Lu, Y
Jin, G
Thomas, SG
Goorsky, MS
Wang, KL
机构
[1] Univ Calif Los Angeles, Dept Elect Engn, Device Res Lab, Los Angeles, CA 90095 USA
[2] Univ Calif Los Angeles, Dept Mat Sci, Los Angeles, CA 90095 USA
关键词
D O I
10.1063/1.124762
中图分类号
O59 [应用物理学];
学科分类号
摘要
A method to grow a relaxed Si0.5Ge0.5 graded layer with a very smooth surface and a very low threading dislocation density using solid-source molecular-beam epitaxy is reported. This method included the use of Sb as a surfactant for the growth of a 2 mu m compositionally graded SiGe buffer with the Ge concentration linearly graded from 0% to 50% followed by a 0.3 mu m constant Si0.5Ge0.5 layer. The substrate temperature was kept at 510 degrees C during the growth. Both Raman scattering and x-ray diffraction were used to determine the Ge mole fraction and the degree of strain relaxation. Both x-ray reflectivity and atomic force microscopy measurements show a surface root mean square roughness of only 20 Angstrom. The threading dislocation density was determined to be as low as 1.5x10(4) cm(-2) as obtained by the Schimmel etch method. This study shows that the use of a Sb surfactant and low temperature growth is an effective method to fabricate high-quality graded buffer layers. (C) 1999 American Institute of Physics. [S0003-6951(99)03837-1].
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页码:1586 / 1588
页数:3
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