The growth and properties of the GaN cap layers crystallized by metalorganic vapor phase epitaxy were studied concerning the composition of the underlying AlGaN layer, type of induced strains and the desorption of the GaN during the initial cooling step after the epitaxy process. The composition of the underlying AlGaN layers was controlled by the growth conditions, while the type of the stresses (tensile or compressive) was induced by applying GaN or AlN buffer layer respectively. Structures with different thicknesses of the GaN cap layer have been grown and analyzed. Three series of samples containing AlGaN underlayers with different aluminium content (20%, 40% and 60%) were grown. The influence of those underlayers composition and type of induced surface strains on the growth of the GaN cap was discussed. High resolution X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and atomic force microscopy, as well as in-situ reflectometry, were used for sample analysis. It has been shown, that the type of surface strains on top of the AlGaN layer and GaN-AlGaN lattice mismatch strongly influence the final cap layer thickness. It was also confirmed, that a significant reduction of the cap thickness causes its discontinuity, leads to the removal of gallium from the top part of the AlGaN layer by evaporation and thus leads to the formation of a thin aluminium-rich layer at the AlGaN/GaN interface.

研究了通过金属有机气相外延结晶的 GaN 盖层的生长和性质，涉及下层 AlGaN 层的成分、诱导应变的类型和外延工艺后初始冷却步骤期间 GaN 的解吸。下面的 AlGaN 层的组成由生长条件控制，而应力的类型（拉伸或压缩）是通过分别应用 GaN 或 AlN 缓冲层引起的。已经生长和分析了具有不同厚度的 GaN 盖层的结构。生长了三个系列的样品，其中包含具有不同铝含量（20%、40% 和 60%）的 AlGaN 底层。讨论了这些底层成分和诱导表面应变类型对 GaN 帽盖生长的影响。高分辨率X射线衍射，X 射线光电子能谱、透射电子显微镜和原子力显微镜以及原位反射计用于样品分析。已经表明，AlGaN 层顶部的表面应变类型和 GaN-AlGaN 晶格失配强烈影响最终的盖层厚度。还证实，帽盖厚度的显着减小导致其不连续性，导致通过蒸发从 AlGaN 层的顶部去除镓，从而导致在 AlGaN/氮化镓界面。AlGaN 层顶部的表面应变类型和 GaN-AlGaN 晶格失配强烈影响最终的盖层厚度。还证实，帽盖厚度的显着减小导致其不连续性，导致通过蒸发从 AlGaN 层的顶部去除镓，从而导致在 AlGaN/氮化镓界面。AlGaN 层顶部的表面应变类型和 GaN-AlGaN 晶格失配强烈影响最终的盖层厚度。还证实，帽盖厚度的显着减小导致其不连续性，导致通过蒸发从 AlGaN 层的顶部去除镓，从而导致在 AlGaN/氮化镓界面。