Effects of buffer layer preparation and Bi concentration on InGaAsBi epilayers grown by gas source molecular beam epitaxy

The effect of using an In0.53Ga0.47As buffer layer on the crystalline quality of InGaAsBi epilayer with Bi concentration up to 3.1% grown by gas source molecular beam epitaxy was investigated. It is found that use of the buffer layer has a dramatic effect on the improvement of surface morphology, structural, electrical and optical properties of InGaAsBi epilayers. Bi incorporation in InGaAs up to a concentration of 3.1% causes no degradation of the electron mobility and induces p-type carriers that compensate the background n-type carriers resulting in mobility enhancement with increasing Bi concentration. With the buffer layer preparation, a maximum electron mobility of 5550 cm(2) V-1 s(-1) at room temperature is demonstrated in InGaAsBi with x(Bi) = 3.1%, which is the highest value reported in InGaAsBi with x(Bi) > 2.5%