Growth Process of GaAs Cap Layers on GaSb/GaAs Quantum Dot Surfaces

Self-assembled GaSb quantum dots (QDs) have been grown on GaAs(001) surface by metal-organic molecular beam epitaxy in the Stranski-Krastanow growth mode. The density of GaSb QDs in a wide range from 5×10
⁸
cm
^-2
to 4×10
¹⁰
cm
^-2
can be controlled by changing the growth temperature between 400°C and 510°C. Etching of GaSb QDs was observed by the supply of trisdimethylaminoarcenic and trisdimethylaminoantimony at the temperature above 450°C. Luminescence from the GaSb/GaAs QDs showed a blue shift by the replacement of Sb with As atoms during GaAs cap growth. To realize long-wavelength emission, 2-step growth of GaAs cap layer was proposed. After GaAs QD structure was grown on the terrace surface between neighboring GaSb QDs at 400°C, the GaAs layer was grown to bury the GaSb and GaAs QDs at 450°C. The red shift of the luminescence peak up to 1.22 μm and the improvement of luminescent efficiency of GaSb/GaAs QDs were observed.