Michael Fahy
The Growth of High Quality InGaAs Quantum Wells
on GaAs(111)A Substrates
Abstract:The ability to grow high quality (InGa)As on the (111)A surface is essential for the production of a wide range of optoelectronic devices, however it has, as yet, received little attention. What work there has been shows it to be highly problematic, reflected in the very broad PL peaks observed for GaAs:InGaAs MQW structures. The origin of this broadening is unclear but is certainly relates to the difficulty in choosing appropriate conditions for the growth III-V's on the (111)A surface. Thus, the poor As sticking coefficient and the subsequent large group III migration lengths on this surface may combine to allow 'alloy clustering' during InGaAs growth, that is the formation of regions of high In composition.
This may be expressed alternatively by stating that it is very easy for the (111)A surface to grow group III rich.
We have undertaken a study of the growth of InGaAs on the GaAs(111)A surface with the goal of achieving high quality MQW structures, the test being the ability to obtain narrow PL line widths. The key to this is an understanding of the growth mechanism and using it to predict the conditions to ensure high lateral and vertical uniformity of In composition within the InGaAs well.
We have demonstrated that 80Å 15% InGaAs(111)A single quantum wells with 12K PL peak widths of less than 8meV can be obtained by growth at 400℃ under a V:III ratio of 5:1.