Effect of barrier thickness on structural, optical, and spectral behaviors of vertically strain coupled InAs/GaAs quantum dot infrared photodetectors

Abstract

The optical, electrical, and spectral properties of a strain coupled InAs quantum dot detector with a fixed quaternary capping of InAlGaAs and variable GaAs barrier thickness were investigated along with an equivalent uncoupled structure. Self-assembled quantum dots with a multimodal dot size distribution were achieved owing to vertical strain coupling. Strain and electronic coupling were utilized to improve the optical and electrical performance of the fabricated quantum dot infrared photodetector. The peak spectral response was tuned by varying barrier thickness, and a blue shift (almost 1 μm) was observed by increasing the capping thickness from sample A (90 Å capping) to E (500 Å capping). High responsivity and detectivity (∼1010 cm Hz1/2/W) were observed for all coupled samples as compared to the uncoupled sample. All coupled samples showed high thermal stability in the photoluminescence peak with high-temperature annealing.

In-Situ Tailoring of Vertically Coupled InAs p-i-p Quantum-Dot Infrared Photodetectors: Toward Homogeneous Dot Size Distribution and Minimization of In–Ga Intermixing

“…This not only leads to the aforementioned shortcomings but also delimits the number of repetitions of QD layers possible in the active region. Previously, researchers have tried to address this issue by several modifications in growth techniques such as (i) optimizing the GaAs spacer layer between the dots, 21 (ii) varying the monolayer coverage, 22 (iii) introducing a strain reducing layer, 23 etc. In this study, we attempt to circumvent these problems by proposing an in situ growth strategy for the formation of highly homogeneous, strain-coupled, defect-less dot layers, which turns out to be a coalescence of some of the strategies enlisted earlier.…”

Impact of an InxGa1–xAs Capping Layer in Impeding Indium Desorption from Vertically Coupled InAs/GaAs Quantum Dot Interfaces

“…The GaAs spacer layer thickness can also be tailored to achieve the desired emission wavelength. 4 Consequently, optimizing the VC stacked structures with GaAs spacer layers grown under different growth parameters is a challenging research topic. It opens new pathways for the application of InAs/GaAs QD heterostructures in telecommunication wavelengths ranging from 1.3 to 1.55 μm.…”

“…We have previously investigated the advantages of using quaternary capping over ternary capping in multistacked InAs QDs. 2,4 In addition, Mohanta et al have discussed the benefits of the carrier relaxation process for different spacer layer thicknesses in multistacked InAs QDs. 9 However, the VC structures also have some shortcomings that weaken the QD coupling.…”

“…Recently, vertical-coupled (VC) InAs/GaAs quantum dot (QD) heterostructures grown by molecular beam epitaxy (MBE) under the Stranski–Krastanov growth mode have shown a tremendous impact on the performance of optoelectronic devices such as solar cells, lasers, light-emitting diodes, IR detectors, and single-photon emitters. − In addition, the optical, structural, and electrical properties of three-dimensionally confined InAs QDs can be tuned over a wide range by designing various multistacked InAs QD heterostructures with different material compositions. The GaAs spacer layer thickness can also be tailored to achieve the desired emission wavelength . Consequently, optimizing the VC stacked structures with GaAs spacer layers grown under different growth parameters is a challenging research topic.…”

“…These uncoupled QD structures degrade the optical quality of InAs/GaAs QD-based devices. Over the past years, extensive research has been carried out to improve the VC stacked structures by methods such as (i) optimizing the GaAs spacer thickness, (ii) introducing a strain-reducing layer, − (iii) varying the material composition of III–V semiconductor alloys of the strain-reducing layer, such as GaAs, InGaAs, , AlGaAs, , InAlGaAs, , GaAsSb, , and InGaAsSb, and (iv) varying the monolayer coverage for the seed-layer InAs QDs in order to achieve a high degree of correlation of vertically aligned QDs with stronger quantum confinement potential. We have previously investigated the advantages of using quaternary capping over ternary capping in multistacked InAs QDs. , In addition, Mohanta et al have discussed the benefits of the carrier relaxation process for different spacer layer thicknesses in multistacked InAs QDs .…”