Compositionally Graded AlGaN Nanostructures: Strain Distribution and X-ray Diffraction Reciprocal Space Mapping

Stanchu, Hryhorii; Maur, Matthias Auf der; Kuchuk, Andrian; Mazur, Yu. I.; Sobanska, M.; Żytkiewicz, Z. R.; Wu, Siliang; Wang, Z.; Salamo, Gregory J.

doi:10.1021/acs.cgd.9b01273

Cited by 7 publications

(5 citation statements)

References 28 publications

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“…Therefore, the BVs of Str_A were significantly enhanced, as shown in figure 19(b). Furthermore, with increased buffer layer thickness, the BV can be further enhanced to 350 V. Additionally, it has been confirmed that graded AlGaN buffer layers can simultaneously improve the crystal quality by modulating the internal strain [118][119][120][121]. Therefore, this type of graded AlGaN back-barrier layer has been widely implemented in AlGaN electronic devices on Si [122][123][124], SiC [125], and sapphire substrates [126][127][128], contributing to the improved crystal quality of AlGaN epilayers and enhanced device performance.…”

Section: Graded Algan Back-barrier Layers For Sufficient Electronmentioning

confidence: 92%

Compositionally graded III-nitride alloys: building blocks for efficient ultraviolet optoelectronics and power electronics

Zhang¹,

Huang²,

Song³

et al. 2021

Rep. Prog. Phys.

132

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Wide bandgap aluminum gallium nitride (AlGaN) semiconductor alloys have established themselves as the key materials for building ultraviolet (UV) optoelectronic and power electronic devices. However, further improvements to device performance are lagging, largely due to the difficulties in precisely controlling carrier behavior, both carrier generation and carrier transport, within AlGaN-based devices. Fortunately, it has been discovered that instead of using AlGaN layers with fixed Al compositions, by grading the Al composition along the growth direction, it is possible to (1) generate high-density electrons and holes via polarization-induced doping; (2) manipulate carrier transport behavior via energy band modulation, also known as ‘band engineering’. Consequently, such compositionally graded AlGaN alloys have attracted extensive interest as promising building blocks for efficient AlGaN-based UV light emitters and power electronic devices. In this review, we focus on the unique physical properties of graded AlGaN alloys and highlight the key roles that such graded structures play in device exploration. Firstly, we elaborate on the underlying mechanisms of efficient carrier generation and transport manipulation enabled by graded AlGaN alloys. Thereafter, we comprehensively summarize and discuss the recent progress in UV light emitters and power electronic devices incorporating graded AlGaN structures. Finally, we outline the prospects associated with the implementation of graded AlGaN alloys in the pursuit of high-performance optoelectronic and power electronic devices.

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Section: Graded Algan Back-barrier Layers For Sufficient Electronmentioning

confidence: 92%

Compositionally graded III-nitride alloys: building blocks for efficient ultraviolet optoelectronics and power electronics

Zhang¹,

Huang²,

Song³

et al. 2021

Rep. Prog. Phys.

132

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“…The dislocations in a crystal and other structural parameters such as the thickness, the alloy mole fraction, the lattice parameters can be calculated by X-ray diffraction (XRD) results, which is nondestructive method. 5,[15][16][17][18] To investigate the dislocation densities that include edge and screw types in terms of the structural quality is important, because the dislocations are one of the main effects that deteriorate the device performance of the HEMTs. [19][20][21] One of the main reasons for the dislocations is the strain relaxation that occurred at the interfaces.…”

Section: Introductionmentioning

confidence: 99%

“…During the growth process of a crystal, unwanted defects, dislocations, and strain may have occurred. The dislocations in a crystal and other structural parameters such as the thickness, the alloy mole fraction, the lattice parameters can be calculated by X‐ray diffraction (XRD) results, which is nondestructive method 5,15–18 . To investigate the dislocation densities that include edge and screw types in terms of the structural quality is important, because the dislocations are one of the main effects that deteriorate the device performance of the HEMTs 19–21 .…”

Section: Introductionmentioning

confidence: 99%

A structural analysis of ultrathin barrier (In)AlN/GaN heterostructures for GaN‐based high‐frequency power electronics

Narin

Kutlu-Narin

Atmaca

et al. 2022

Surface & Interface Analysis

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Metal-organic chemical vapor deposition (MOCVD) is one of the best growth methods for GaN-based materials as well-known. GaN-based materials with very quality are grown the MOCVD, so we used this growth technique to grow InAlN/ GaN and AlN/GaN heterostructures in this study. The structural and surface properties of ultrathin barrier AlN/GaN and InAlN/GaN heterostructures are studied by X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements. Screw, edge, and total dislocation densities for the grown samples have been calculated by using XRD results. The lowest dislocation density is found to be 1.69 Â 10 8 cm À2 for Sample B with a lattice-matched In 0.17 Al 0.83 N barrier. The crystal quality of the studied samples is determined using (002) symmetric and (102) asymmetric diffractions of the GaN material. In terms of the surface roughness, although reference sample has a lower value as 0.27 nm of root mean square values (RMS), Sample A with 4-nm AlN barrier layer exhibits the highest rough surface as 1.52 nm of RMS. The structural quality of the studied samples is significantly affected by the barrier layer thickness.The obtained structural properties of the samples are very important for potential applications like high-electron mobility transistors (HEMTs).

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“…At the same time, proper engineering of both spontaneous and piezo-polarization fields permits the intentional and favorable tuning of the electronic properties of IIInitrides. For example, the activation of impurity dopants by the polarization charge in compositionally graded AlGaN semiconductors found very receptive applications in the fabrication of efficient DUV-LEDs and p-n junctions [23][24][25][26][27]. This polarization doping depends intimately on biaxial strain (piezo-polarization) and alloy composition (spontaneous polarization).…”

Section: Introductionmentioning

confidence: 99%

Coherent-interface-induced strain in large lattice-mismatched materials: A new approach for modeling Raman shift

et al. 2021

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Strain engineering as one of the most powerful techniques for tuning optical and electronic properties of Ill-nitrides requires reliable methods for strain investigation. In this work, we reveal, that the linear model based on the experimental data limited to within a small range of biaxial strains (< 0.2%), which is widely used for the non-destructive Raman study of strain with nanometer-scale spatial resolution is not valid for the binary wurtzite-structure group-III nitrides GaN and AlN. Importantly, we found that the discrepancy between the experimental values of strain and those calculated via Raman spectroscopy increases as the strain in both GaN and AlN increases. Herein, a new model has been developed to describe the strain-induced Raman frequency shift in GaN and AlN for a wide range of biaxial strains (up to 2.5%). Finally, we proposed a new approach to correlate the Raman frequency shift and strain, which is based on the lattice coherency in the epitaxial layers of superlattice structures and can be used for a wide range of materials. Electronic Supplementary Material Supplementary material is available for this article at 10.1007/s12274-021-3855-4 and is accessible for authorized users.

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Compositionally Graded AlGaN Nanostructures: Strain Distribution and X-ray Diffraction Reciprocal Space Mapping

Cited by 7 publications

References 28 publications

Compositionally graded III-nitride alloys: building blocks for efficient ultraviolet optoelectronics and power electronics

Compositionally graded III-nitride alloys: building blocks for efficient ultraviolet optoelectronics and power electronics

A structural analysis of ultrathin barrier (In)AlN/GaN heterostructures for GaN‐based high‐frequency power electronics

Coherent-interface-induced strain in large lattice-mismatched materials: A new approach for modeling Raman shift

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