Ameliorating the optical and structural properties of InAs quantum dot heterostructures through digital alloy capping materials: Theory and experiment

Kumar, Rohit; Saha, Jhuma; Panda, Debiprasad; Kumar, Rajneesh; Gazi, Sanowar Alam; Gourishetty, Raveesh; Chakrabarti, Subhananda

doi:10.1016/j.optmat.2020.110419

Cited by 8 publications

(3 citation statements)

References 32 publications

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“…The capping layer can be deposited over the QDs in many ways, viz. conventional capping, digital alloy capping [6][7][8][9], and linear alloy capping [10,11]. In the linear alloy approach, the composition of capping material is decreasing linearly from the apex of QD towards the top GaAs layer.…”

Section: Introductionmentioning

confidence: 99%

Impact of linear alloy on strain coupled bilayer InAs/GaAs1-ySby quantum dot heterostructures

Kumar¹,

Saha²,

Chakrabarti³

2023

Physics and Simulation of Optoelectronic Devices XXXI

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In this work, the concept of the novel approach called linear alloy capping layer (LACL) has been investigated on the strain-coupled bilayer InAs/GaAs1-ySby QD heterostructures. Here, two analog structures with low (structure BA1) and high (structure BA2) antimony (Sb) contents, and one linear alloyed structure (BL) with varying Sb-content inside the capping layer is considered. The Sb-content inside the CL of structure BA1 and BA2 are 10% and 20%, respectively. Whereas, it is varying linearly from 20% to 10% inside structure BL. The CL and GaAs spacer layer thickness has been taken as 8 nm and 13 nm, respectively. All these three structures have been modeled using Nextnano++ simulation software. Two strain components, hydrostatic and biaxial have been computed and compared. These two strain components help in decreasing the ground state energy gap which leads to a red-shifted PL emission. The structure BL offers improved biaxial strain by 1.11% and 0.56% inside QD compared to structures BA1 and BA2. In addition, the magnitude of hydrostatic strain inside QD of structure BL is reduced by 1.78% and increased by 0.64% compared to structures BA1 and BA2. The strain inside the CL of structure BL is reduced very smoothly in a linear fashion as compared to other analog structures. The computed PL emission of structures BA1, BA2, and BL are 1371 nm, 1665 nm, and 1617 nm, respectively. Also, the proposed structure BL offers a type-II band profile. Hence this proposed approach is useful for future optoelectronic applications.

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Section: Introductionmentioning

confidence: 99%

Impact of linear alloy on strain coupled bilayer InAs/GaAs1-ySby quantum dot heterostructures

Kumar¹,

Saha²,

Chakrabarti³

2023

Physics and Simulation of Optoelectronic Devices XXXI

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“…While, its visible range transparency and n-type conductivity makes it a potential candidate for UV optoelectronics application as a transparent conducting oxide (TCO). [13] The n type conductivity can be linked with the oxygen vacancies (Vos) present in the Ga2O3 matrix, which can act as shallow donors. [14] Furthermore, β-Ga2O3 demonstrates strong room-temperature (RT) photoluminescence (PL) which can be tuned for its potential application as phosphor of LEDs.…”

Section: Introductionmentioning

confidence: 99%

Oxygen mediated optical and electrical property modification of RF sputtered Ga2O3 thin films for photodetector application

Bhowmick

Saha

Mishra

et al. 2022

Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XIX

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The deep UV photodetectors (DUV-PDs) are technologically important for diverse applications, ranging from environmental monitoring, space communication etc. Among all solar blind materials Ga2O3 thin film shows its strong contention owing to its intrinsic solar-blind nature. However, the PD’s efficiency can be significantly affected by the defects such as oxygen vacancies (VO). Both the deficiency and surplus of oxygen during Ga2O3 thin film deposition can result in the formation of carrier scattering centers, sub-bandgap absorption, and leakage channels. In this work, we have studied the impact of oxygen flow rate (OFR) on the optical and electrical properties of RF sputtered Ga2O3 thin film. The Ga2O3 thin films were deposited on p-Si at room temperature, where the Ar to O2 ratio has been varied from 1:0, 1:1, to 1:2 to maintain the O2 poor and O2 rich condition. The XRD spectrum shows the presence of two peaks positioned at ~33.0° , and ~64.5° , which are further identified as β(-202), and β(-313), respectively for samples grown without oxygen. The top view FESEM images confirm the uniform film growth for both O2 rich conditions while some isolated bubble-like and grain-like structures are witnessed in ratios 1:0, and 1:1, respectively. The change in optical bandgap for all the samples is determined using diffuse reflectance spectra which show the bandgap values lie in the range of 4.1 eV-4.2 eV. Furthermore, the deconvoluted photoluminescence spectra (in the range of λ=300-500 nm) show the change in different types of Vo defects originating due to OFR induced structural asymmetry in the Ga2O3 thin film. Finally, the change in dark current in Ga2O3/p-Si heterojunctions is estimated from current-voltage (I-V) characteristics to understand the effect of OFR on its electrical properties for future DUV detectors.

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“…The flexible bandgap engineering of DA contributes to extending the operating wavelength of optoelectronic devices [10,11]. In addition, the digital growth method also is utilized as a capping layer in quantum dot heterostructures to reduce the strain of the subcapping layer and improve the carrier lifetime [12].…”

Section: Introductionmentioning

confidence: 99%

Fine modulation of the energy band strategy to control the carrier confinement capability of digital alloys

Cao¹,

Wu²,

Zhao³

et al. 2022

Nanotechnology

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In this paper, a strategy to finely modulate the energy band structure to control the carrier confinement capability of digital alloys (DA) is proposed. Strain analysis shows that As and Sb atoms are exchanged within the AlAsSb DA. The bottom of the corrected potential well is low on the left and high on the right in the growth direction, resulting in a higher band offset of the AlSb potential barrier layer on the left side of the potential well than on the right side. The modulation of the band leads to a higher probability of electron tunneling in DA under the action of an electric field opposite to the growth direction. Conversely, it is difficult for the electrons to tunnel into the lower energy level potential wells. The I-V curve of DA shows that the current value under positive bias is significantly smaller than the value under negative bias when the voltage is higher. The measured results correspond perfectly with the modified energy band model, which verifies the feasibility of energy band modulation. This is important for the structural design of DA and the reduction of dark current in optoelectronic devices.

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Ameliorating the optical and structural properties of InAs quantum dot heterostructures through digital alloy capping materials: Theory and experiment

Cited by 8 publications

References 32 publications

Impact of linear alloy on strain coupled bilayer InAs/GaAs1-ySby quantum dot heterostructures

Impact of linear alloy on strain coupled bilayer InAs/GaAs1-ySby quantum dot heterostructures

Oxygen mediated optical and electrical property modification of RF sputtered Ga2O3 thin films for photodetector application

Fine modulation of the energy band strategy to control the carrier confinement capability of digital alloys

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