Influence of InGaAs matrix thickness on the optical properties and strain distribution in self-assembled sub-monolayer InAs quantum dot heterostructures

Abstract

In this study, we have discussed the effect of strain distribution and optical properties on In0.14Ga0.86As matrix thickness variation (tmat) in self-assembled InAs quantum dot (QD) heterostructure using temperature and power-dependent photoluminescence (PL) measurements. The calculated ground-state transition energies are 1.12, 1.14 and 1.09 eV for tmat of 2, 4 and 6 ML (monolayer) In0.14Ga0.86As matrix thickness respectively. We also discern that the full-width at half-maximum (FWHM) broadens gradually as temperatures increases due to electron-phonon scattering. The calculated activation energy (Ea) values are 231, 302 and 98 meV for increasing tmat. The partial strain relief due to varying In0.14Ga0.86As layer thickness occurs due to QD size tunability by preventing Indium (In) segregation effect, that sets the possibility to understand about InAs inter-band and intersubband transitions of PL emission. This has been validated with HRXRD results where strain decreases linearly with increasing tmat. Here In0.14Ga0.86As layer acts as a strain-reducing layer (SRL) in QD heterostructure as well. Thus helps in reducing the hydrostatic strain (∊hyd) of InAs QDs, while the lower InGaAs layer increases the QD density, leading to a remarkable rise in PL intensity due to state filling of carriers. The effect of strain distribution for varying tmat in the heterostructure was also studied using nextnano++ simulations. The relative percentage change in hydrostatic (biaxial) strain was calculated to be 5.5% (8%) respectively. Thus, the results so obtained can help in tuning matrix thickness on the PL emission properties of QDs and therefore in the realization of several optoelectronic devices.