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E Monroy - One of the best experts on this subject based on the ideXlab platform.

  • Internal Quantum Efficiency of algan aln Quantum dot superlattices for electron pumped ultraviolet sources
    Nanotechnology, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, E Belletamalric, Quangminh Thai, C Dujardin, Ioanna Dimkou, S T Purcell, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of ≈ 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (0 ≤ x ≤ 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>1011cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below ≈ 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

  • Internal Quantum Efficiency of algan aln Quantum dot superlattices for electron pumped ultraviolet sources
    arXiv: Materials Science, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, E Belletamalric, Quangminh Thai, C Dujardin, Ioanna Dimkou, S T Purcell, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (x = 0, 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>10e11 cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

  • Internal Quantum Efficiency of AlGaN/AlN Quantum dot superlattices for electron-pumped ultraviolet sources
    arXiv: Materials Science, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, C Dujardin, Ioanna Dimkou, S T Purcell, E. Bellet-amalric, Q.-m. Thai, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (x = 0, 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>10e11 cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

Shing-chung Wang - One of the best experts on this subject based on the ideXlab platform.

  • Internal Quantum Efficiency measurement in InGaN/GaN UV LEDs with patterned sapphire substrate by photoluminescence and electroluminescence method
    CLEO QELS: 2010 Laser Science to Photonic Applications, 2010
    Co-Authors: C. H. Wang, Ching-hua Chiu, Chih Chun Ke, T.c. Lu, Shing-chung Wang
    Abstract:

    Internal Quantum Efficiency (IQE) of InGaN-based ultraviolet light emitting diodes (LED) grown on patterned sapphire substrate (PSS) and flat sapphire were measured by photoluminescence and electroluminescence methods. The IQE improvement of PSS LED is significant.

  • study of the excitation power dependent Internal Quantum Efficiency in ingan gan leds grown on patterned sapphire substrate
    IEEE Journal of Selected Topics in Quantum Electronics, 2009
    Co-Authors: Ching-hua Chiu, Tien-chang Lu, Chih Chun Ke, Shing-chung Wang
    Abstract:

    The mechanisms of the excitation power dependent Internal Quantum Efficiency in InGaN/GaN multiple Quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the Internal Quantum Efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-Efficiency LED devices. Experimentally, the Internal Quantum Efficiency of the LED grown on the PSS is ~70% and that of the LED grown on the planar sapphire substrate is ~62%. For the LED grown on the PSS, the observed higher Internal Quantum Efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high Internal Quantum Efficiency.

  • Study of the Excitation Power Dependent Internal Quantum Efficiency in InGaN/GaN LEDs Grown on Patterned Sapphire Substrate
    IEEE Journal of Selected Topics in Quantum Electronics, 2009
    Co-Authors: Ching-hua Chiu, Tien-chang Lu, Chih Chun Ke, Shing-chung Wang
    Abstract:

    The mechanisms of the excitation power dependent Internal Quantum Efficiency in InGaN/GaN multiple Quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the Internal Quantum Efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-Efficiency LED devices. Experimentally, the Internal Quantum Efficiency of the LED grown on the PSS is ~70% and that of the LED grown on the planar sapphire substrate is ~62%. For the LED grown on the PSS, the observed higher Internal Quantum Efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high Internal Quantum Efficiency.

A Harikumar - One of the best experts on this subject based on the ideXlab platform.

  • Internal Quantum Efficiency of algan aln Quantum dot superlattices for electron pumped ultraviolet sources
    Nanotechnology, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, E Belletamalric, Quangminh Thai, C Dujardin, Ioanna Dimkou, S T Purcell, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of ≈ 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (0 ≤ x ≤ 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>1011cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below ≈ 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

  • Internal Quantum Efficiency of algan aln Quantum dot superlattices for electron pumped ultraviolet sources
    arXiv: Materials Science, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, E Belletamalric, Quangminh Thai, C Dujardin, Ioanna Dimkou, S T Purcell, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (x = 0, 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>10e11 cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

  • Internal Quantum Efficiency of AlGaN/AlN Quantum dot superlattices for electron-pumped ultraviolet sources
    arXiv: Materials Science, 2020
    Co-Authors: A Harikumar, Fabrice Donatini, Catherine Bougerol, C Dujardin, Ioanna Dimkou, S T Purcell, E. Bellet-amalric, Q.-m. Thai, E Monroy
    Abstract:

    In this paper, we describe the growth and characterization of 530-nm-thick superlattices (100 periods) of AlxGa1-xN/AlN (x = 0, 0.1) Stranski-Krastanov Quantum dots for application as the active region of electron-beam pumped ultraviolet lamps. Highly dense (>10e11 cm-2) Quantum dot layers are deposited by molecular beam epitaxy, and we explore the effect of the III/V ratio during the growth process on their optical performance. The study considers structures emitting in the 244-335 nm range at room temperature, with a relative linewidth in the 6-11% range, mainly due to the QD diameter dispersion inherent in self-assembled growth. Under electron pumping, the emission Efficiency remains constant for acceleration voltages below 9 kV. The correlation of this threshold with the total thickness of the superlattice and the penetration depth of the electron beam confirms the homogeneity of the nanostructures along the growth axis. Below the threshold, the emission intensity scales linearly with the injected current. The Internal Quantum Efficiency is characterized at low injection, which reveals the material properties in terms of non-radiative processes, and high injection, which emulates carrier injection in operation conditions. In Quantum dots synthesized with III/V ratio < 0.75, the Internal Quantum Efficiency remains around 50% from low injection to pumping power densities as high as 200 kW/cm2, being the first kind of nanostructures that present such stable behaviour.

Ching-hua Chiu - One of the best experts on this subject based on the ideXlab platform.

  • Internal Quantum Efficiency measurement in InGaN/GaN UV LEDs with patterned sapphire substrate by photoluminescence and electroluminescence method
    CLEO QELS: 2010 Laser Science to Photonic Applications, 2010
    Co-Authors: C. H. Wang, Ching-hua Chiu, Chih Chun Ke, T.c. Lu, Shing-chung Wang
    Abstract:

    Internal Quantum Efficiency (IQE) of InGaN-based ultraviolet light emitting diodes (LED) grown on patterned sapphire substrate (PSS) and flat sapphire were measured by photoluminescence and electroluminescence methods. The IQE improvement of PSS LED is significant.

  • study of the excitation power dependent Internal Quantum Efficiency in ingan gan leds grown on patterned sapphire substrate
    IEEE Journal of Selected Topics in Quantum Electronics, 2009
    Co-Authors: Ching-hua Chiu, Tien-chang Lu, Chih Chun Ke, Shing-chung Wang
    Abstract:

    The mechanisms of the excitation power dependent Internal Quantum Efficiency in InGaN/GaN multiple Quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the Internal Quantum Efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-Efficiency LED devices. Experimentally, the Internal Quantum Efficiency of the LED grown on the PSS is ~70% and that of the LED grown on the planar sapphire substrate is ~62%. For the LED grown on the PSS, the observed higher Internal Quantum Efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high Internal Quantum Efficiency.

  • Study of the Excitation Power Dependent Internal Quantum Efficiency in InGaN/GaN LEDs Grown on Patterned Sapphire Substrate
    IEEE Journal of Selected Topics in Quantum Electronics, 2009
    Co-Authors: Ching-hua Chiu, Tien-chang Lu, Chih Chun Ke, Shing-chung Wang
    Abstract:

    The mechanisms of the excitation power dependent Internal Quantum Efficiency in InGaN/GaN multiple Quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the Internal Quantum Efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-Efficiency LED devices. Experimentally, the Internal Quantum Efficiency of the LED grown on the PSS is ~70% and that of the LED grown on the planar sapphire substrate is ~62%. For the LED grown on the PSS, the observed higher Internal Quantum Efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high Internal Quantum Efficiency.

Andrew Sarangan - One of the best experts on this subject based on the ideXlab platform.

  • Schottky-Barrier Photodiode Internal Quantum Efficiency Dependence on Nickel Silicide Film Thickness
    IEEE Photonics Journal, 2019
    Co-Authors: Joshua Duran, Andrew Sarangan
    Abstract:

    In this paper we show that the Internal Quantum Efficiency of NiSi Schottky-barrier photodetectors can be significantly improved as the silicide film thickness is reduced close to its percolation threshold. We fabricated photodetectors in two optical configurations (front-side and back-side illuminated) at four different film thicknesses between 1-4 nm as well as a thick (100 nm) reference device. We simultaneously fit the reflection and transmission data for each silicide film on silicon as well as for front and backside illuminations to extract the refractive index dispersion of each film. Using this technique, we can accurately determine the absorption of each constituent layer and extract the wavelength-dependent Internal Quantum Efficiency from the external Quantum Efficiency. We show that the Internal Quantum Efficiency is highly dependent on the silicide film thickness while the dark current is not. The Internal Quantum Efficiency of our thinnest detector is the highest reported of any silicide Schottky-barrier photodetector of comparable barrier height to date with a 57× improvement over the thick (reference) device. Using an approximation to Vickers' model, we were able to fit the IQE spectra to extract the hot carrier mean-free path of electrons in NiSi.

  • Internal Quantum Efficiency Dependence on Thickness of NiSi Schottky Barrier Photodetectors
    2018 IEEE Photonics Conference (IPC), 2018
    Co-Authors: Joshua Duran, Andrew Sarangan
    Abstract:

    We investigate the thickness dependence of Internal Quantum Efficiency for NiSi/n-Si Schottky barrier photodetectors. We observe a 20-fold improvement between the thinnest and thickest films tested and find that Internal Quantum Efficiency improves until the film becomes discontinuous, falling below its percolation thickness.