Controlling the compositional inhomogeneities in AlxGa1−xN/AlyGa1−yN MQWs grown by PA-MBE: Effect on luminescence properties

Pramanik, Pallabi; Singha, Chirantan; Roy, Anindita; Das, Alakananda; Sen, Sabyasachi; Bhattacharyya, Anirban; Kumar, Deepak; Rao, D.V. Sridhara

doi:10.1016/j.jcrysgro.2016.01.004

Cited by 17 publications

(8 citation statements)

References 26 publications

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“…On the other hand, the presence of two separated peaks, LS 1 (P 4 ) and LS 2 (P 5 ), in the PL emission from localized states can be ascribed to a multiple‐components DOS due to the variation of disorder sources in semiconductor alloys. For example, beside the compositional fluctuations, the existence of a metallic group‐III layer on the growth surface during the deposition process of Al x Ga 1‐ x N/Al y Ga 1‐ y N QWs, leads to a multiple‐peaks PL emission from localized states .…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, as a result of the low surface mobility of Al atoms, these atoms are not sufficiently able to do movements from their point of impact on the surface to energetically favorable lattice steps –during the growth process of AlGaN layers . Besides, imperfect interfaces lead to an increase in the disorder potential in the case of semiconductor heterostructures, e.g., Al x Ga 1‐x N/Al y Ga 1‐ y N quantum wells (QWs) .…”

Section: Introductionmentioning

confidence: 99%

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Luminescence dynamics in AlGaN with AlN content of 20%

Soltani

Bouzidi

Touré

et al. 2016

Phys. Status Solidi A

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Optical properties and carrier dynamics of an AlGaN layer with an AlN content of 20% have been studied using time‐resolved photoluminescence (TR‐PL). Despite the high density of defects due to the relatively high AlN content, an intense PL emission from the sample has been detected. Low‐temperature PL spectra exhibit several features, accompanied by a strong emission‐wavelength dependence of the PL decay time. A significant red‐shift of more than 200 meV from the band edge is recorded for the PL emission from localized states. Temperature‐dependent PL spectra of the sample are dominated by the emission from localized states and, furthermore, show a relatively slight decrease by almost an order of magnitude with increasing temperature from 45 to 300 K. Our observations indicate strong, spatial localization effects of carriers, resulting in an increase in the radiative recombination rate.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Luminescence dynamics in AlGaN with AlN content of 20%

Soltani

Bouzidi

Touré

et al. 2016

Phys. Status Solidi A

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“…The use of AlN buffer layer significantly reduces the dislocation density and improves the overall structural quality of the SL layers as well as the quantum efficiency of the MQW optoelectronic device. 8,29,30,36,37 In order to confirm it, a bi-layer thin film of Al 0.50 Ga 0.50 N(~300 nm)/AlN(~200 nm) (schematic Fig. 2(a)) was also studied for its symmetry allowed Raman phonon modes of AlN-E 2 H and AlN-A 1 (LO) along with the presence of IF modes (Fig.…”

Section: 2326mentioning

confidence: 93%

“…A large number of threading dislocations were reported in the as-prepared nucleation layers of SLs. 29,30 However, a reduction of the dislocation density was observed in the sample during the deposition of the bulk AlGaN or AlN film (~300 nm) before starting the MQW deposition which might help to construct the active region relatively free from the dislocations. The detailed growth process and its basic characterizations were reported in our previous articles for studying the optoelectronic properties.…”

Section: Experimental Details 21 Synthesis Of Mqw Structuresmentioning

confidence: 99%

Interface phonon modes in the [AlN/GaN]₂₀ and [Al_0.35Ga_0.65N/Al_0.55Ga_0.45N]₂₀ 2D multi-quantum well structures

Sivadasan

Singha

Bhattacharyya

et al. 2016

Phys. Chem. Chem. Phys.

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“…It is to be noted that the c-plane GaN has very large lattice mismatch with Si, sapphire and the associated strain relaxation manifests in GaN films in the form of high density of microstructural defects, viz., misfit dislocations (MDs), threading dislocations (TDs), inversion domains (IDs), V-defects, etc. The electron microscopy methods, viz., weakbeam dark field imaging (WBDF), convergent beam electron diffraction (CBED), electron back scattered diffraction (EBSD), electron-energy loss spectroscopy and EDS methods are suitable for the detailed investigation of microstructural and compositional aspects [16][17][18][19][20][21][22][23][24][25] and the micro details are given in a detailed technical report 26 . These techniques have been applied for the study of these microstructural issues in GaN films.…”

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confidence: 99%

Microstructural and Compositional Characterisation of Electronic Materials

et al. 2016

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Microstructural and compositional characterisation of electronic materials in support of the development of GaAs, GaN and GaSb based multilayer device structures is described. Electron microscopy techniques employing nanometer and sub-nanometer scale imaging capability of structure and chemistry have been widely used to characterise various aspects of electronic and optoelectronic device structures such as InGaAs quantum dots, InGaAs pseudomorphic (pHEMT) and metamorphic (mHEMT) layers and the ohmic metallisation of GaAs and GaN high electron mobility transistors, nichrome thin film resistors, GaN heteroepitaxy on sapphire and silicon substrates, as well as InAs and GaN nanowires. They also established convergent beam electron diffraction techniques for determination of lattice distortions in III-V compound semiconductors, EBSD for crystalline misorientation studies of GaN epilayers and high-angle annular dark field techniques coupled with digital image analysis for the mapping of composition and strain in the nanometric layered structures. Also, in-situ SEM experiments were performed on ohmic metallisation of pHEMT device structures. The established electron microscopy expertise for electronic materials with demonstrated examples is presented. Keywords:Electronic materials, semiconductor electronic device, nanowires, infrared device structure REVIEW ARTICLE DEf. SCI. J., VOl. 66, NO. 4, July 2016 342 techniques for quantitative lattice distortion studies in III-V thin films & polarity of GaN based films 5,6 (e) quantitative strain/compositional studies of epitaxial thin films by the digital analysis of HRTEM images 7(f) quantitative analysis of heterointerfaces by atomic-column ratio mapping (g) in-situ SEM studies, and (h) compositional analysis by EDS and EELS techniques.An overview of GaAs, GaSb and GaN multilayer semiconductor device structures and the application of advanced electron microscopy techniques to study various issues in these materials development programs are presented. GaAs HEMt dEVIcE StructurESHEMT is a field effect transistor in which the channel is a quantum well (QW) realised by embedding a narrow bandgap semiconductor (such as InGaAs) between two wide bandgap semiconductors (e.g., GaAs and AlGaAs) and the carriers (two-dimension electron gas, 2DEG) in channel are populated by modulation doping.GaAs devices are made as pHEMTs (pseudomorphic HEMTs) and mHEMTs (metamorphic HEMTs). The schematics of these devices are shown as Fig. 1. It is to note that the increase of indium content in the In x Ga 1-x As channel enhances the saturation velocity and mobility of carriers, hence for given HEMT device features (for example, gate length), mHEMT has highest f T (the gain of the device is measured as a function of frequency, it decreases with frequency and reaches to unity at f T ), which is desirable for the device applications.grading by varying the indium content. In this case, misfit dislocations can originate and propagate as threading dislocations in the overgrown epilayers, if...

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Controlling the compositional inhomogeneities in AlxGa1−xN/AlyGa1−yN MQWs grown by PA-MBE: Effect on luminescence properties

Cited by 17 publications

References 26 publications

Luminescence dynamics in AlGaN with AlN content of 20%

Luminescence dynamics in AlGaN with AlN content of 20%

Interface phonon modes in the [AlN/GaN]₂₀ and [Al_0.35Ga_0.65N/Al_0.55Ga_0.45N]₂₀ 2D multi-quantum well structures

Microstructural and Compositional Characterisation of Electronic Materials

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Controlling the compositional inhomogeneities in AlxGa1−xN/AlyGa1−yN MQWs grown by PA-MBE: Effect on luminescence properties

Cited by 17 publications

References 26 publications

Luminescence dynamics in AlGaN with AlN content of 20%

Luminescence dynamics in AlGaN with AlN content of 20%

Interface phonon modes in the [AlN/GaN]20 and [Al0.35Ga0.65N/Al0.55Ga0.45N]20 2D multi-quantum well structures

Microstructural and Compositional Characterisation of Electronic Materials

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Interface phonon modes in the [AlN/GaN]₂₀ and [Al_0.35Ga_0.65N/Al_0.55Ga_0.45N]₂₀ 2D multi-quantum well structures