Graded GaAsSb strain reducing layers covering InAs/GaAs quantum dots

摘要

We have grown new InAs/GaAs quantum dot (QD) structures with graded Sb concentration of GaAs_(1-x)Sb_x strain reducing layer (SRL). New types of GaAsSb SRLs with graded concentration of Sb are theoretically and experimentally studied. We compare properties of three different Sb concentration gradients in SRL, constant, increasing and decreasing during the growth. Both types of non-constant gradients help us to prevent transition of the InAs(QD)/GaAsSb(SRL) heterojunction from type Ⅰ to type Ⅱ, to increase emission wavelength and to retain high luminescence intensity of these types of QP structures. Comparison of photoluminescence of samples with different concentration gradients and similar average Sb concentration in SRLs is showa The longest wavelength of type Ⅰ ground state transition was achieved on sample with decreasing gradation of Sb content in SRL—1399 nm (0.886 eV).