Growth of high Bi concentration GaAs1-xBix by molecular beam epitaxy

The incorporation of Bi is investigated in the molecular beam epitaxy growth of GaAs1-xBix. Bi content increases rapidly as the As2:Ga flux ratio is lowered to 0.5 and then saturates for lower flux ratios. Growth under Ga and Bi rich conditions shows that Bi content increases strongly with decreasing temperature. A model is proposed where Bi from a wetting layer incorporates through attachment to Ga-terminated surface sites. The weak Ga-Bi bond can be broken thermally, ejecting Bi back into the wetting layer. Highly crystalline films with up to 22% Bi were grown at temperatures as low as 200 degree C.