NUCLEATION OF WAVY GROWTH MODES IN QUANTUM-WELL STACKS OF III-V COMPOUND ALLOYS

The influence of strain and temperature on the development of 3D islan d growth patterns (wavy layer growth) and the establishment of a defin ed modulation period in epitaxially grown multiple quantum well struct ures of the III-V compound alloys is discussed. Experimental evidence for a previously derived theoretical roughening transition curve, whic h separates 2D monolayer from 3D island growth is presented. In this p aper we furthermore derive the f(2) similar to lambda(-1) relationship between misfit strain f and modulation wavelength lambda, and give ex perimental evidence. Ultra-high resolution scanning transmission elect ron microscopy (STEM) analysis is performed in the above alloys to inv estigate the occurrence of alloy inhomogeneities. In parallel, highly dislocated regions in the multiple quantum well (MQW) stacks are syste matically studied by transmission electron microscopy (TEM). The latte r two investigations are undertaken in order to establish possible nuc leation sites and to better understand the nucleation process for the 3D growth mode.