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Last name: NGO
First name: Thi Huong
International audience
International audience
Undoubtedly, tourism is growing strongly worldwide, especially in developing countries and rural areas. Tourism has both positive and negative impacts on tourist destinations that link sustainable development's economic, social, and environmental components. The local community's attitude is crucial for future tourism planning, management, and...
GaN high electron mobility transistors (HEMT) are becoming the mainstream for high frequency and power switching applications. On the other hand, Ultra-Wide Band Gap (UWBG) materials such as AlN that has a bandgap of 6.2 eV are attracting attention for pushing the limits of high voltage power devices. In this work, we report on AlGaN/GaN-on-AlN...
We comparatively study the onset of photo-induced non-radiative intrinsic Auger recombination processes for red, yellow and green light emitting InGaNsingle bondGaN hetero-structures grown along the polar orientation. We find a dramatic reduction of the photo excitation densities triggering the domination of Auger effect with increasing...
The variation of the internal quantum efficiency (IQE) of single InGaN quantum well structures emitting from blue to red is studied as a function of the excitation power density and the temperature. By changing the well width, the indium content, and adding a strain compensation AlGaN layer, we could tune the intrinsic radiative recombination...
The Auger effect and its impact on the internal quantum efficiency (IQE) of yellow light emitters based on silicon-doped InGaN–AlGaN–GaN quantum wells are investigated by power dependence measurement and using an ABC model. Photoluminescence intensity recorded as a function of excitation power density follows a linear dependence up to a...
We determine the internal quantum efficiency of strain-balanced AlGaN-InGaN-GaN hetero-structures designed for yellow-amber light emission, by using a recent model based on the kinetics of the photoluminescence decay initiated by Yoshiya Iwata, Ryan G. Banal, Shuhei Ichikawa, Mitsuru Funato, and Yoichi Kawakami, Journal of Applied Physics 117,...
The optical properties of Al0.1Ga0.9N nanostructures grown by molecular beam epitaxy on Al0.5Ga0.5N (0001) templates are investigated. By combining morphological and photo- luminescence (PL) characterizations, we have performed an in-depth analysis of the nanostructures properties as a function of the deposited amount. It is shown that: 1) the...
In this work, two series of AlGaN/GaN/AlN high electron mobility transistor (HEMT) heterostructures have been grown by molecular beam epitaxy on AlN bulk substrates. The effects of reduction in the GaN channel thickness as well as the AlGaN barrier thickness and composition on structural and electrical properties of the heterostructures have...
We investigate the optical properties of porous GaN films of different porosities, focusing on the behaviors of the excitonic features in time-integrated and time-resolved photoluminescence. A substantial enhancement of both excitonic emission intensity and recombination rate, along with insignificant intensity weakening under temperature rise,...
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Time-resolved photoluminescence spectra of orange light emitting (Ga,In)N-based devices have been grown by metal-organic vapour phase epitaxy on C plane sapphire for indium compositions ranging up to 23 percents. The temperature dependent time resolved photoluminescence spectra collected through the 8K-300K range are found to exhibit behaviours...
In this work, we investigate the impact of the quantum confined Stark effect and of the carrier localization on the internal quantum efficiency of polarized single or multiple InxGa1-xN/GaN quantum well(s), and semi-polar (11e22) multiple InxGa1-xN/InyGa1-yN quantum well. We find that increasing the influence of the quantum confined Stark...
AlGaN based light emitting diodes (LEDs) will play a key role for the development of applications in the ultra-violet (UV). In the UVB region (280–320 nm), phototherapy and plant lighting are among the targeted uses. However, UVB LED performances still need to be improved to reach commercial markets. In particular, the design and the...
International audience
The optical properties of AlyGa1-yN quantum dots (QDs), with y 1⁄4 0 or y 1⁄4 0.1, in an AlxGa1 xN matrix are studied. The influence of the QD layer design is investigated pointing out the correlations between the QD structural and optical properties. In a first part, the role of the epitaxial strain in the dot self-assembling process is...
AlN nucleation layer is the key issue for the performance of GaN high frequency telecommunication and power switching systems fabricated after heteroepitaxy on Silicon or Silicon Carbide. In this work, we demonstrate and explain both the low level and the origin of propagation losses in GaN/3C–SiC/Si High Electron Mobility Transistors (HEMTs)...
International audience
In this work, an AlGaN/GaN HEMT structure is grown on a 0.8 μm thick 3C-SiC layer on high resistivity Silicon substrate. The RF propagation losses are investigated and compared with the ones of epi-layers grown directly on Silicon and on 6H-SiC substrates. Short gate length transistors are fabricated using e-beam lithography. In spite of ohmic...
Herein, the interest of cubic silicon carbide as a template for the growth of AlGaN/ GaN high electron mobility transistor (HEMT) heterostructures on silicon substrates for high-frequency operation is shown. On the one hand, 0.6-0.8 μm-thick 3C-SiC grown by chemical vapor deposition on intrinsic silicon substrate having initial resistivity...
Herein, the interest of cubic silicon carbide as a template for the growth of AlGaN/ GaN high electron mobility transistor (HEMT) heterostructures on silicon substrates for high-frequency operation is shown. On the one hand, 0.6-0.8 μm-thick 3C-SiC grown by chemical vapor deposition on intrinsic silicon substrate having initial resistivity...
This work aims to understand the origin of propagation losses in GaN-on-Si devices at microwave frequencies thanks to original AFM's electrical modes such as scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM). AlN films on Si substrate were grown using Metalorganic Vapor Phase Epitaxy (MOVPE) technique....
The paper explores the Deep Level Transient Fourier Spectroscopy (DLTFS) capabilities in characterizing electrically active traps in vertical GaN-on-GaN Schottky barrier diodes (SBDs). The capacitance-DLTFS (C-DLTFS) experiments reveal a prominent electron trap T2 at EC-0.56 eV with a density (NT2) of 8×10 14 cm-3 and a weak presence of another...
AlN nucleation layers are the basement of GaN-on-Si structures grown for light-emitting diodes, high frequency telecommunication and power switching systems. In this context, our work aims to understand the origin of propagation losses in GaN-on-Si High Electron Mobility Transistors at microwaves frequencies, which are critical for efficient...