Misfit dislocation formation in lattice-mismatched III - V heterostructures grown by metal - organic vapour phase epitaxy
Misfit dislocation formation in lattice-mismatched III - V heterostructures grown by metal - organic vapour phase epitaxy
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金属有机气相外延晶格失配III-V族异质结构中错配位错的形成
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
L. Giling
中科院分区：
文献类型：
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作者：
J. Nijenhuis;P. Wel;E. V. Eck;L. Giling
本文研究了在拉应力和压应力作用下晶格失配的Ⅲ-Ⅴ族异质结中失配位错的形成。用金属有机物汽相外延法在铟浓度为0.1 ~ 1.1%的衬底上生长了受拉应力的GaAs层。在GaAs衬底上生长了铟浓度在0.5%和2.5%之间的压缩应变层。对于拉伸应力下的层的不对称位错图案已被观察到，而压缩应变层显示出对称的位错图案。提出了一个描述弛豫过程的模型，该模型通过形成解离的六边形半环位错来描述。两种可能的错配位错类型的迁移率的差异被发现是在低生长温度下的不对称应变消除的起源。在拉伸应力下的层中，螺旋位错的交叉滑移被剪切应力抵消，导致仅在一个方向上松弛。在压应力下的层中，成核的失配位错可以经历交叉滑移，导致在表面处的交叉阴影图案。在较高的生长温度下，由于较高的位错迁移率，位错图案变得更加对称。由于位错的局部积累，在张应力下生长的层的表面上形成生长丘。在较高的生长温度下，由于位错的迁移率较高，这种小丘生长被阻止。它还表明，（错误）取向的衬底是揭示了由非平行组的位错线观察到在一个松弛的外延层的表面。
Misfit dislocation formation in lattice-mismatched III - V heterostructures both under tensile and under compressive stress has been studied. Layers of GaAs under tensile stress have been grown by metal - organic vapour phase epitaxy on substrates with indium concentrations between 0.1 and 1.1%. Compressively strained layers with indium concentrations between 0.5 and 2.5% have been grown on GaAs substrates. For the layers under tensile stress an asymmetrical dislocation pattern has been observed, whereas the compressively strained layers show a symmetrical dislocation pattern. A model describing the relaxation process by the formation of dissociated hexagonally shaped half-loop dislocations is proposed. A difference in the mobilities of the two possible misfit dislocation types is found to be the origin of asymmetrical strain relief at low growth temperatures. In layers under tensile stress the cross slipping of screw dislocations is counteracted by the shear stress, leading to relaxation in only one direction. In layers under compressive stress the nucleated misfit dislocations can undergo cross slipping, resulting in a cross hatched pattern at the surface. At higher growth temperatures the dislocation patterns become more symmetrical due to the higher dislocation mobilities. Growth hillocks are formed on the surfaces of the layers grown under tensile stress, due to local accumulation of dislocations. This hillock growth is prevented at higher growth temperatures by the higher mobility of the dislocations. It is also shown that the (mis)orientation of the substrate is revealed by non-parallel groups of dislocation lines observed at the surface of a relaxed epilayer.