Growth kinetics and structural perfection of (InN)_1/(GaN)_(1-20) short-period superlattices on +c-GaN template in dynamic atomic layer epitaxy

摘要

The growth kinetics and structural perfection of (InN)_1/(GaN)_(1-20) short-period superlattices (SPSs) were investigated with their application to ordered alloys in mind. The SPSs were grown on +c-GaN template at 650 ℃ by dynamic atomic layer epitaxy in conventional plasma-assisted molecular beam epitaxy. It was found that coherent structured InN/GaN SPSs could be fabricated when the thickness of the GaN barrier was 4 ML or above. Below 3 ML, the formation of SPSs was quite difficult owing to the increased strain in the SPS structure caused by the use of GaN as a template. The effective or average In composition of the (InN)_1/(GaN)_4 SPSs was around 10%, and the corresponding InN coverage in the ～1 ML-thick InN wells was 50%. It was found that the effective InN coverage in ～1 ML-thick InN wells could be varied with the growth conditions. In fact, the effective In composition could be increased up to 13.5%, i.e., the corresponding effective InN coverage was about 68%, by improving the capping/freezing speed by increasing the growth rate of the GaN barrier layer.