Monitoring Ga and In desorption and In surface segregation during MBE using atomic absorption

The use of an atomic absorption flux monitor for measuring desorbing gallium and indium atoms during MBE is demonstrated. Several short InAs layers of known thickness were grown on a GaAs substrate. By desorbing these layers in a controlled substrate temperature ramping cycle, a calibration between the atomic absorption signal and desorption rate was determined. This calibration was then used to measure the desorption of excess indium that segregates to the surface during the growth of InGaAs for a range of In compositions. The atomic absorption signals were also measured for growth of GaAs and InGaAs at elevated substrate temperatures where the cation sticking coefficients are less than unity.