DEVICE QUALITY IN0.4GA0.6AS GROWN ON GAAS BY MOLECULAR-BEAM EPITAXY

A novel approach to growing device quality In0.4Ga 0.6As epilayers on GaAs is reported which involves the controlled propagation of dislocations via a carefully designed multistage strain-relief buffer system. Cross-sectional transmission electron microscopy analysis revealed the In0.4Ga0.6As epilayers to be threading dislocation free in contrast to the heavily dislocated material obtained by growing In0.4Ga0.6As directly on GaAs. Hall effect measurements performed on unintentionally doped buffered In0.4Ga 0.6As epilayers indicated the room-temperature electron concentrations in the epilayers to be around 1×1015 cm -3 while electron mobilities were around 4700 cm2 V -1 s-1. In addition, strong band-edge photoluminescence was recorded from the buffered epilayers, the luminescence peak occurring at 1304 nm having a linewidth around 7 meV at 13 K.