Experimental Detection on Thickness Fluctuation of In_xGa_1-xAs-Based Indium-Rich Cluster Structure

The thickness detection of quantum well has always been the research focus, especially for In _x Ga _1-x As-based indium-rich cluster (IRC) structure, which has a thickness fluctuation of normal and indium-deficient InGaAs layers caused by IRC effect. In this paper, a simple and effective detection method for the special IRC structure is proposed by point-to-point acquisition. The photoluminescence (PL) spectra emitted from different In _x Ga _1-x As positions are measured by moving the metal mask with a 0.2-mm-diameter light hole. By establishing the relationship between In _x Ga _1-x As thickness and spectral intensity, the thickness fluctuation of normal In _0.17 Ga _0.83 As and indium-deficient In _0.12 Ga _0.88 As layers is determined by comparing the intensity of dual peaks. The dual peaks are typical feature of this IRC structure, which is caused by the migration of indium atoms. The significance of this experimental results is that it not only can detect the thickness distribution of In _x Ga _1-x As materials with different x values, but also determine the critical thickness of indium atom migration in the growth of highly strained quantum well.