Dynamic atomic layer epitaxy of InN on/in +c-GaN matrix: Effect of 'In+N' coverage and capping timing by GaN layer on effective InN thickness

摘要

The growth front in the self-organizing and self-limiting epitaxy of ～1 monolayer (ML)-thick InN wells on/in +c-GaN matrix by molecular beam epitaxy (MBE) has been studied in detail, with special attention given to the behavior and role of the N atoms. The growth temperatures of interest are above 600 ℃, far higher than the typical upper critical temperature of 500 ℃ in MBE. It was confirmed that 2 ML-thick InN wells can be frozen/inserted in GaN matrix at 620 ℃, but it was found that N atoms at the growth front tend to selectively re-evaporate more quickly than In atoms at temperatures higher than 650 ℃. As a result, the effective thickness of inserted InN wells in the GaN matrix at 660-670 ℃ were basically 1 ML or sub-ML, even though they were capped by a GaN barrier at the time of 2 ML "In+N" coverage. Furthermore, it was found that the N atoms located below In atoms in the dynamic atomic layer epitaxy growth front had remarkably weaker bonding to the +c-GaN surface.