Investigation of strain profile and band-alignment study in InAs/GaAsSb quantum dot heterostructure with varying Sb content

The current work represents the influence of Sb composition on strain profiles, band alignment of InAs/GaAsSb Stranski-Krastanov (SK) quantum dots (QD) heterostructure. A single layer InAs/GaAs SK QD heterostructure has been utilised as a reference structure (sample A). Three different structures B, C and D are chosen with the Sb composition of 10%, 14% and 22% in the capping layer on the InAs QDs. The strain distribution of InAs quantum dots with GaAs1-xSbx capping has been investigated in detail by using Nextnano simulation software. The transition from type-I to type-II band alignment occurs after 14% Sb incorporation. The effect of variation in the Sb component on the strain profile is analysed in terms of hydrostatic and biaxial strain. In the strain profiles, the biaxial strain increases significantly from samples A to D, whereas the hydrostatic strain is reducing from samples A to D inside the QD region simultaneously. Further, low temperature photoluminescence (PL) has been performed to validate the simulated results. The PL peak is originated at ~1030 nm for sample A, which shows a good agreement with the simulated value ~1071 nm. With the similar dot size, the simulated PL peaks are found at 1116, 1284, 1675 nm for samples B, C and D, respectively. A slight variation is observed in the experimentally obtained PL peaks and simulated one due to the incorporation of higher Sb content. With the higher Sb content, relatively more defects are generated, which affects the experimental PL peaks. Also, a red shift is found in the PL peaks from ~1030 nm to ~1213 nm at 19K and it gives an insight to develop various optoelectronic devices using such QDs heterostructure.