Electrical Engineering Department, University of California at Los Angeles, Los Angeles, CA, 90095, USA.
Nanoscale Res Lett. 2009 Aug 30;4(12):1458-62. doi: 10.1007/s11671-009-9420-9.
We report structural analysis of completely relaxed GaSb epitaxial layers deposited monolithically on GaAs substrates using interfacial misfit (IMF) array growth mode. Unlike the traditional tetragonal distortion approach, strain due to the lattice mismatch is spontaneously relieved at the heterointerface in this growth. The complete and instantaneous strain relief at the GaSb/GaAs interface is achieved by the formation of a two-dimensional Lomer dislocation network comprising of pure-edge (90°) dislocations along both [110] and [1-10]. In the present analysis, structural properties of GaSb deposited using both IMF and non-IMF growths are compared. Moiré fringe patterns along with X-ray diffraction measure the long-range uniformity and strain relaxation of the IMF samples. The proof for the existence of the IMF array and low threading dislocation density is provided with the help of transmission electron micrographs for the GaSb epitaxial layer. Our results indicate that the IMF-grown GaSb is completely (98.5%) relaxed with very low density of threading dislocations (105 cm-2), while GaSb deposited using non-IMF growth is compressively strained and has a higher average density of threading dislocations (>109 cm-2).
我们报告了使用界面失配（IMF）阵列生长模式在 GaAs 衬底上外延生长的完全弛豫 GaSb 外延层的结构分析。与传统的四方畸变方法不同，这种生长方式中晶格失配引起的应变在异质界面上是自发释放的。GaSb/GaAs 界面处的完全和瞬时应变松弛是通过形成二维 Lomer 位错网络实现的，该网络由纯边缘（90°）位错构成，沿[110]和[1-10]方向排列。在本分析中，比较了使用 IMF 和非 IMF 生长的 GaSb 的结构特性。Moiré 条纹图案和 X 射线衍射测量了 IMF 样品的长程均匀性和应变弛豫。借助 GaSb 外延层的透射电子显微镜图，提供了 IMF 阵列存在和低位错密度的证据。我们的结果表明，IMF 生长的 GaSb 完全弛豫（98.5%），位错密度非常低（105 cm-2），而使用非 IMF 生长的 GaSb 是压缩应变的，具有更高的平均位错密度（>109 cm-2）。
