Enhanced luminescence from InGaN/GaN nano-disk in a wire array caused by surface potential modulation during wet treatment

Saha, D.; Pendem, Vikas; Chouksey, Shonal; Udai, Ankit; Aggarwal, Tarni; Ganguly, Swaroop; Saha, Dipankar

doi:10.1088/1361-6528/aaf8de

Cited by 6 publications

(8 citation statements)

References 41 publications

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“…[65] IQE of 30 nm QD sample is obtained to be 70%, and 12 nm QD sample is 78%. [68] For better insight, slow time constant t 2 is plotted in the vicinity of InGaN band-edge for QD and QW samples with increasing pump power, as shown in Figure 8d-f, respectively. It is evident that t 2 is almost unchanged near the InGaN band-edge.…”

Section: Carrier Decay Kineticsmentioning

confidence: 99%

“…We have studied and compared the ultrafast nonlinear carrier and photon dynamics in InGaN/GaN nanostructures of various dimensions (varying degree of quantum confinement). InGaN-based QWs (2D), quantum wires (QWIs; 1D) [65,66] and QDs (0D) [67,68] are fabricated for this purpose. In 0.14 Ga 0.86 N/GaN QW heterostructure is grown by metalorganic chemical vapor deposition (MOCVD) on a c-plane sapphire substrate.…”

Section: Fabrication Of Ingan/gan 2d 1d and 0d Nanostructuresmentioning

confidence: 99%

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Investigation of Ultrafast Carrier Dynamics in InGaN/GaN‐Based Nanostructures Using Femtosecond Pump–Probe Absorption Spectroscopy

Aggarwal

Udai

Banerjee

et al. 2021

Physica Status Solidi (b)

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III-V compound semiconductors laid the foundation for optoelectronic devices and solid-state lighting with wavelengths ranging from infrared to ultraviolet regions. Infrared to green light-emitting diodes (LEDs) were invented in the early 1960s. [1][2][3] However, blue LEDs took another three decades to get established, considering the challenges in defect-free high-quality growth, [4][5][6] and controlled p-doping of wide-bandgap semiconductors. [7][8][9][10] The success of blue LEDs was accomplished by the development of gallium-nitride (GaN) alloyed with indium and aluminum in the late 1980s. [11,12] GaN and related materials have a wurtzite crystal structure and direct bandgap, making them ideal for bright LEDs and laser diodes (LDs). In order to move the emission wavelength to the visible range (2-3.4 eV), InN is alloyed with GaN. [13,14] Advancement in GaN-based LEDs revolutionized the white broadband lighting when laminated with yellow phosphorous coating. Nakamura et al. developed the first high-quality InGaN back in 1992, which paved the way for III-nitride blue and green LEDs/ LDs. [15] In 1995-1996, Nakamura made true blue LEDs possible by developing recombination regions with InGaN. [16] III-nitride devices acquire a wide area of applications due to their wavelength tunability by varying the alloy composition of In and Al in InGaN and AlGaN, respectively. [17,18] Moreover, an additional degree of freedom can be achieved using quantum-confined nanostructures. Emission wavelength and surface/interface material properties can be altered by reducing the dimensionality/size of the devices. [19][20][21] quantum well (QW; 2D), [22][23][24] vertical/lateral nanowires (1D), [25][26][27][28][29] and quantum dots (QDs; 0D) [30][31][32][33] are among the most important quantum-confined nanostructures used in the active regions of modern optoelectronic devices including LEDs, lasers, photodetectors, and solar cells. Improved internal quantum efficiency, [34][35][36] large surface-to-volume ratio, [37] low power

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Section: Carrier Decay Kineticsmentioning

confidence: 99%

Section: Fabrication Of Ingan/gan 2d 1d and 0d Nanostructuresmentioning

confidence: 99%

Investigation of Ultrafast Carrier Dynamics in InGaN/GaN‐Based Nanostructures Using Femtosecond Pump–Probe Absorption Spectroscopy

Aggarwal

Udai

Banerjee

et al. 2021

Physica Status Solidi (b)

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“…The various phenomena leading to the change in the characteristics include quantum confinement, strain relaxation, polarization, exciton binding energy, and surface potential. The surface potential is usually minimal for smaller radii of the QDs, which is estimated to be ∼1.0 meV for radius <50 nm . The decrease in the size of the QD increases quantum confinement in the radial direction.…”

mentioning

confidence: 85%

“…The surface potential is usually minimal for smaller radii of the QDs, which is estimated to be ∼1.0 meV for radius <50 nm. 36 The decrease in the size of the QD increases quantum confinement in the radial direction. The QDs are assumed to be circular in nature for theoretical calculations in determining quantum confinement.…”

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confidence: 99%

Femto-Second Carrier and Photon Dynamics in Site Controlled Hexagonal InGaN/GaN Isolated Quantum Dots: Natural Radial Potential Well and Its Dynamic Modulation

et al. 2020

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Quantum dot (QD) is slated to play a significant role in quantum technologies through its usage as a single-photon source. It also has promising applications as efficient light emitters through strain-relaxed structures. This work demonstrates the fabrication of high-quality site controlled InGaN/GaN QDs through a large contribution of chemical etching in an otherwise reactive ion etching process. Uniform sized QDs with a hexagonal base and radii of 15 and 6 nm are fabricated and characterized by photoluminescence and femtosecond transient absorption spectroscopy. The natural exposition of the inherent hexagonal base is a signature of the reduced defects in these dots. The QDs show the intuitive additional quantum confinement due to size reduction, and the photoluminescence peaks manifest a blue shift. The absorption spectra indicate that the QDs are heavily strain-relaxed at smaller radii, and their characteristics as a function of size and pump power are investigated. The degree of strain relaxation and change in energy-band diagram as a function of position along the radius are also determined. The changes are prominent near the periphery, which creates a natural potential well for both electrons and holes, restricting the carriers from reaching the sidewalls. Femtosecond carrier dynamics indicate a lower capture rate for the smaller size of the dots, indicating excessive electrical or optical pumping will not necessarily lead to increased luminescence. The radiative decay of carriers is faster for strain-relaxed QDs due to higher oscillator strength originating from increased electron−hole wave function overlap. Higher pump power is found to decrease the radiative rate due to the increased effective size of the QDs and thereby reducing carrier injection density. This is in stark contrast to the frequently observed increased decay rate due to Auger recombination. Dynamic modification of the size of the QDs by pump power may find potential use in optoelectronic applications.

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“…Auger recombination is a significant contributor to efficiency droop due to its cubic dependence on the free carrier density. Various techniques have been explored to prevent SRH and Auger recombinations; this includes core-shell nanorods , (provide reduced polarization charges), wide quantum wells (QWs), reverse polarization, semi- and nonpolar GaN, , defect-free GaN nanowires, and quantum dots − (which have less Auger coefficient than their planar counterparts). The growth of high-quality InGaN layers on a semi- or nonpolar substrate is difficult.…”

Section: Introductionmentioning

confidence: 99%

Reduced Auger Coefficient through Efficient Carrier Capture and Improved Radiative Efficiency from the Broadband Optical Cavity: A Mechanism for Potential Droop Mitigation in InGaN/GaN LEDs

Aggarwal

Udai

Saha

et al. 2022

ACS Appl. Mater. Interfaces

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Efficiency droop at high carrier-injection regimes is a matter of concern in InGaN/GaN quantum-confined heterostructure-based light-emitting diodes (LEDs). Processes such as Shockley–Reed–Hall and Auger recombinations, electron–hole wavefunction separation from polarization charges, carrier leakage, and current crowding are identified as the primary contributors to efficiency droop. Auger recombination is a critical contributor owing to its cubic dependence on carrier density, which can not be circumvented using an advanced physical layout. Here, we demonstrate a potential solution through the positive effects from an optical cavity in suppressing the Auger recombination rate. Besides the phenomenon being fundamentally important, the advantages are technologically essential. The observations are manifested by the ultrafast transient absorption pump-probe spectroscopy performed on an InGaN/GaN-based multi-quantum well heterostructure with external DBR mirrors of varying optical confinement. The optical confinement modulates the nonlinear carrier and photon dynamics and alters the rate of dominant recombination mechanisms in the heterostructure. The carrier capture rate is observed to be increasing, and the polarization field is reducing in the presence of optical feedback. Reduced polarization increases the effective bandgap, resulting in the suppression of the Auger coefficient. Superluminescent behavior along with enhanced spectral purity in the emission spectra in presence of optical confinement is also demonstrated. The improvement is beyond the conventional Purcell effect observed for the quantum-confined systems.

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Enhanced luminescence from InGaN/GaN nano-disk in a wire array caused by surface potential modulation during wet treatment

Cited by 6 publications

References 41 publications

Investigation of Ultrafast Carrier Dynamics in InGaN/GaN‐Based Nanostructures Using Femtosecond Pump–Probe Absorption Spectroscopy

Investigation of Ultrafast Carrier Dynamics in InGaN/GaN‐Based Nanostructures Using Femtosecond Pump–Probe Absorption Spectroscopy

Femto-Second Carrier and Photon Dynamics in Site Controlled Hexagonal InGaN/GaN Isolated Quantum Dots: Natural Radial Potential Well and Its Dynamic Modulation

Reduced Auger Coefficient through Efficient Carrier Capture and Improved Radiative Efficiency from the Broadband Optical Cavity: A Mechanism for Potential Droop Mitigation in InGaN/GaN LEDs

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