annealed Ga(NAsP) quantum well structure
Image courtesy of Microsc. and Microanal.

Abstract

The epitaxial growth of multi component semiconductor layers such as Ga(NAsP) enables the improvement of laser and transistor devices due to the individually tunable band gap and lattice constant. Furthermore, the material system shows great potential for realizing optical light sources on Si substrate. Due to the low temperature growth conditions used for this metastable material system, point defects are incorporated in the material upon growth. In particular the thermal annealing procedure after growth can reduce the number of crystal defects and thus increase the efficiency of active regions of the devices. One drawback of the thermal treatment is the gradual blur of the interfaces between the quantum wells and the barriers. To improve the understanding of the annealing process and in turn to improve the quality of the material system Ga(NAsP), (scanning) transmission electron microscopy ((S)TEM) investigations are indispensable. Especially the in situ observation of annealing effects during (S)TEM investigations can help to understand the physics behind these processes as many aspects of the formation of such complex materials are still unknown. Thereby the growth and annealing conditions can be optimized to improve the optical properties. From a more fundamental point of view, also the quantitative determination of the chemical composition of the quaternary alloy on an atomic scale as well as an understanding of the local effects like strain or atomic disorder on STEM contrast presents a true challenge, which is addressed in this study.

Impact Statement

Extended abstract of a paper presented the epitaxial growth of multi component semiconductor layers such as Ga(NAsP) enables the improvement of laser and transistor devices due to the individually tunable band gap and lattice constant. Furthermore, the material system shows great potential for realizing optical light sources on Si substrate.