Reduction of threading dislocations in N-polar GaN using a pseudomorphicaly grown graded-Al-fraction AlGaN interlayer

Li, Liang; Yang, Lin‐An; Cao, Rongtao; Xu, Shuai; Zhou, Xiaowei; Xue, JunShuai; Lin, Zhiyu; Ha, Wei; Zhang, Jincheng

doi:10.1016/j.jcrysgro.2013.10.036

Cited by 9 publications

(7 citation statements)

References 25 publications

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“…It has been shown that dislocations are more prone to bend and relax the compressive stresses when the dislocation lines intersect a smooth surface; however, this is followed by cracking of the graded AlGaN layer on Si. An improvement of the crystal quality of N-polar GaN layers with a pseudomorphically grown graded AlGaN interlayer on GaN(0001) was reported in ref . It was shown that the insertion of the AlGaN interlayer causes both inclination and annihilation of TDs under tensile strain as opposed to the well-known compressive strain inclination and annihilation reaction .…”

Section: Introductionmentioning

confidence: 89%

Local Strain and Crystalline Defects in GaN/AlGaN/GaN(0001) Heterostructures Induced by Compositionally Graded AlGaN Buried Layers

Stanchu

Kuchuk

Mazur

et al. 2018

Crystal Growth & Design

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Plastic strain relaxation in epitaxial layers is one of the crucial factors that limits the performance of III-nitride-based heterostructures. In this work, we report on strain relaxation and crystalline defects in heterostructures consisting of compositionally graded AlGaN epitaxial layers tensile-strained between a GaN-buffer and a GaN-cap. We demonstrate the effects of Al concentration and the shape of the concentration-depth profile in the buried graded layers on the accumulated elastic strain energy and how this influences the critical thickness for crack generation or fracture. It is shown that this fracture leads to the formation of partially relaxed regions with their degree of strain relaxation directly related to the density of cracks. Nevertheless, even though the in-plane coherency between the AlGaN layer and the GaN-buffer is broken, the in-plane coherency within the AlGaN layer is preserved for all regions. Furthermore, the tensile strain released in the buried graded AlGaN layers is consistent with compressive strain induced in the GaN-cap layers. Finally, the localized stress and the densities of threading dislocations are correlated with the features of the resulting fractured heterostructures. These results are important toward the control of complex plastic strain relaxation and further facilitate the growth of high quality compositionally graded AlGaN-based devices.

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Section: Introductionmentioning

confidence: 89%

Local Strain and Crystalline Defects in GaN/AlGaN/GaN(0001) Heterostructures Induced by Compositionally Graded AlGaN Buried Layers

Stanchu

Kuchuk

Mazur

et al. 2018

Crystal Growth & Design

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“…The back-to-back graded AlGaN could be epitaxially grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) on the Ga-face (0111) GaN buffer layer [20,21,27,28]. The feasible processing steps of the BGA-HFET will be discussed at the end herein.…”

Section: Introductionmentioning

confidence: 99%

Simulation of a high-performance enhancement-mode HFET with back-to-back graded AlGaN layers

Yang

Deng

et al. 2019

Sci. China Inf. Sci.

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A novel three-dimensional hole gas (3DHG) enhancement-mode (E-mode) heterostructure fieldeffect transistor (HFET) is proposed and investigated. It features back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer, which form polarization gradient and subsequently induce the three-dimensional electron gas (3DEG) and 3DHG in the positiveand negative-graded AlGaN layers, respectively. The source and drain are located at the same side of the metal-insulator-semiconductor (MIS) trench gate, and the source is in contact with the HfO 2 gate insulator. First, the on-state current is significantly improved owing to the high-density 3DEG in the positive-graded AlGaN. Next, the vertical conductive channel between the source and 3DEG is blocked by the 3DHG, thereby realizing the E-mode. The threshold voltage (V th) can be modulated by a partial doping conductive channel. Subsequently, a high breakdown voltage (BV) is obtained, because the polarization junction formed by the polarization charges assists in depleting the drift region in the off-state. Next, the BGA-HFET is smaller than the conventional HFET (Con-HFET) owing to the special location of the source. The BV of the proposed HFET sharply increases to 919 V from 39 V of the Con-HFET with the same gate-drain spacing, and the saturation drain current is increased by 103.5%.

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“…Ma et al [13] have reported the AlN/GaN superlattice interlayer for both stress and dislocation engineering, thus obtaining an enhanced optical output power of unpackaged light-emitting diode chips on Si substrates. However, previous literatures mainly focus on the final strain relaxation but there are only few reports on the detailed generation and propagation of the TDs after the introduction of various interlayers, as well as the micro-structural defects within the interlayer [14][15][16]. In our previous publication on unintentionally doped high resistivity GaN grown with an in-situ annealed InGaN interlayer, the interlayer-induced increase of the edge-type TDs was demonstrated by transmission electron microscopy (TEM) and high-resolution X-ray diffraction (HR-XRD) to reveal the high resistivity mechanisms [17].…”

Section: Introductionmentioning

confidence: 99%

Strain and microstructures of GaN epilayers with thick InGaN interlayer grown by MOCVD

Liu

Liang

Liu

et al. 2017

Materials Science in Semiconductor Processing

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GaN epilayers with thick InGaN interlayer are grown by metal-organic chemical vapor deposition on sapphire substrates. The as-grown GaN films with an InGaN interlayer show remarkable relaxed compressive strain measured by Raman spectroscopy. The microstructures within the InGaN interlayer were investigated by high resolution transmission electron microscopy. It indicated that the misfit dislocations and stacking faults in the InGaN interlayer formed, which is responsible for the relaxation of the lattice strain. In addition, the InGaN interlayer was found to terminate most of threading dislocation from the GaN pseudosubstrate layer even though the strain relaxation occurs. Such data help to provide further insight into the strain relaxation mechanisms and improve the quality of GaN films and the performance of GaN related devices.

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Reduction of threading dislocations in N-polar GaN using a pseudomorphicaly grown graded-Al-fraction AlGaN interlayer

Cited by 9 publications

References 25 publications

Local Strain and Crystalline Defects in GaN/AlGaN/GaN(0001) Heterostructures Induced by Compositionally Graded AlGaN Buried Layers

Local Strain and Crystalline Defects in GaN/AlGaN/GaN(0001) Heterostructures Induced by Compositionally Graded AlGaN Buried Layers

Simulation of a high-performance enhancement-mode HFET with back-to-back graded AlGaN layers

Strain and microstructures of GaN epilayers with thick InGaN interlayer grown by MOCVD

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