InAs quantum dot-in-a-well heterostructures with InGaAs, GaAsN and GaAsSb well using digital alloy capping layer

In this work, the authors introduced a novel approach called digital alloy capping layer (DACL) and investigated its effect on the optical and structural properties of InAs quantum dot-in-a-well (DWELL) heterostructures. In DACL, a conventional thick well layer is digitized equally with different compositions analogous to short-period-superlattice (SPS). The DACL approach's effect has been studied experimentally and theoretically on DWELL heterostructures with In<inf>x</inf>Ga<inf>1-x</inf>As as the well material. The photoluminescence (PL) study reveals that DACL observes a red-shift of ∼55 nm as compared to AACL approached heterostructures. High-resolution X-ray diffraction (HRXRD) results reveal higher In-content, controlled In-out diffusion from InAs QD, and improved in-plane strain in DACL samples compared to the analog sample. The study has been extended to QD heterostructures with GaAs<inf>1-x</inf>N<inf>x</inf> and GaAs<inf>1-y</inf>Sb<inf>y</inf> as well materials, and comprehensive analysis has been carried out. Hence, the DWELL heterostructures with the DACL approach can be utilized to fabricate infrared photodetector devices.