Strain Minimization of InAs QDs Heterostructures Using Dual Quaternary-Ternary/Ternary-Quaternary Capping Materials via Digital Alloy Capping Layer Approach

The role of combinational (ternary and quaternary) capping layers to understand the strain distribution mechanism and optical properties through digital alloy capping layer (DACL) has been presented in this work. GaAsSb as ternary and InGaAsSb as quaternary capping materials have been used, and a combination of ternary-quaternary/quaternary-ternary has been implemented. Digital alloy technique has been employed to cover the quantum dots with the combinational capping materials. The biaxial as well as hydrostatic strain is obtained using Nextnano++ software and compared to analyze the strain distribution inside the heterostructure. Digital alloyed structures offer a red shift in emission wavelength (∼ 2 μm) compared to conventional structures based on the selection of capping material. However, the selection of capping materials (GaAsSb and InGaAsSb) exhibits both type-I as well as type-II band profiles which can be utilized in multiple optoelectronic applications. This detailed theoretical study of the digital and analog alloy approach of the combinational ternary/quaternary and quaternary/ternary capping layer would help to optimize advanced futuristic device heterostructures with reduced strain and better crystal quality.