M. Siebert

InGaN Selfassembled Quantum Dots Investigated By X‐Ray Diffraction‐Anomalous‐Fine Structure Technique

Local chemical composition of InGaN quantum dots grown by molecular‐beam epitaxy on GaN virtual substrates was investigated by x‐ray diffraction anomalous fine‐structure method. Using this approach, we found that the In content increases from 20% at the dot base to 40–50% at the top. From the detailed numerical analysis of the data we were able to reconstruct the local neighborhood of Ga atoms in different positions in the dots, as well as the local elastic relaxation state.

Local structure of uncapped and capped InGaN/GaN quantum dots

The local structure around the indium atoms in uncapped and capped In(x)Ga(1-x)N quantum dots has been studied by In K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The samples were grown by metal organic vapour phase epitaxy. The EXAFS was successfully applied to study the structural properties of buried quantum dots which are not optically active. The analysis revealed that capping the quantum dots with GaN does not affect the bond distances of the In-N and In-Ga, but makes the In-In distance shorter by 0.04 A.