Optimization of dot layer periodicity through analysis of strain and electronic profile in vertically stacked InAs/GaAs Quantum dot heterostructure

Abstract

Constraints of the single layer quantum dot (QD) led to the investigation of alternative heterostructures for the next generation high performance optoelectronic devices. In this work, the periodicity of strain-coupled QD layers were optimized via growing Bilayer, Trilayer, Pentalayer, and Heptalayer structures with a novel perspective. Both theoretical and experimental investigations were done to acquire a better understanding of the dot periodicity. Proposed QD structures exhibited redshift in the PL peaks compared to the uncoupled one. Monomodal dot size distribution and narrow full width half maximum (FWHM) were observed for Bilayer, and Trilayer quantum dot infrared photodetectors (QDIPs). However, an increase in the FWHM in the Pentalayer QDIP, and a multimodal dot size distribution in the Heptalayer QDIP were witnessed. The highest activation energy (303.42 meV) claimed by the Trilayer sample substantiated better vertical confinement of carriers. There was a 24.4% enhancement in the activation energy, and 3.7% reduction in the FWHM value of PL peak for the Trilayer sample, compared to the uncoupled QDIP. For accentuating the advantages of Trilayer QDIP, measurements of photoluminescence excitation (PLE), IV characteristics and spectral response were carried out and compared with others. The Trilayer device with optimized periodicity of QD layers offered the lowest dark current density (3.7 × 10−6 A/cm2 at −1 V, 77 K), high temperature operability (90 K), and peak responsivity of 461 mA/W (at −2 V, 90 K).