Method of determination of AIGaAsSb layer composition in molecular beam epitaxy processes with regard to unintentional As incorporation

摘要

The accurate determination of the chemical composition of multicomponent antimonide layers still remains difficult. The problem becomes even more complicated when group III antimonides are grown in a MBE chamber that is also used for the growth of group III arsenides. In this paper, the composition of MBE grown AIGaAsSb layers is investigated in the context of unintentional arsenic incorporation. Control of the As concentration and a determination of the AlGaSb composition are crucial for an accurate calculation of the AIGaAsSb stoichiometry. It has been found that when using diffraction measurements with an As detection limit of 0.087%, the Al content in Alo.5Gao.5Sb is determined with an accuracy of ±1%. Taking into account the GaSb reference from secondary ion mass spectrometry, the accuracy can be increased to ±0.52% of Al. The Al/Ga ratio determined for AlGaSb layers is further used for the calculation of the As content in AIGaAsSb alloys grown under the same technological conditions as the ternary layer. As a result, the procedure for the accurate determination of stoichiometry coefficients in this material is recommended.