Effect of stress on the Al composition evolution in AlGaN grown using metal organic vapor phase epitaxy

He, Chenguang; Qin, Zhixin; Xu, Fujun; Zhang, Lisheng; Wang, Jiaming; Hou, Mengjun; Zhang, Shan; Wang, Xinqiang; Ge, Weikun; Shen, Bo

doi:10.7567/apex.9.051001

Cited by 8 publications

(12 citation statements)

References 27 publications

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“…Recently, some researches have demonstrated that during the growth of AlGaN layer, strong compressive strain can pull Ga atom from the AlGaN epilayer to reduce the strain energy, leading to the growth of AlGaN alloy with high Al content [ 23 , 38 ]. As an analogy, if there exists a strong tensile strain field, Al atom may also be pulled out from AlGaN, resulting in a higher Ga composition.…”

Section: Resultsmentioning

confidence: 99%

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Luo

et al. 2022

Nanoscale Res Lett

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A systematic study was carried out for strain-induced microscale compositional pulling effect on the structural and optical properties of high Al content AlGaN multiple quantum wells (MQWs). Investigations reveal that a large tensile strain is introduced during the epitaxial growth of AlGaN MQWs, due to the grain boundary formation, coalescence and growth. The presence of this tensile strain results in the microscale inhomogeneous compositional pulling and Ga segregation, which is further confirmed by the lower formation enthalpy of Ga atom than Al atom on AlGaN slab using first principle simulations. The strain-induced microscale compositional pulling leads to an asymmetrical feature of emission spectra and local variation in emission energy of AlGaN MQWs. Because of a stronger three-dimensional carrier localization, the area of Ga segregation shows a higher emission efficiency compared with the intrinsic area of MQWs, which is benefit for fabricating efficient AlGaN-based deep-ultraviolet light-emitting diode.

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Section: Resultsmentioning

confidence: 99%

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Luo

et al. 2022

Nanoscale Res Lett

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“…Experimentally, lattice relaxation has been assessed by X-ray diffraction (XRD) measurements in many heterosystems, including Al x Ga 1−x N/AlN. [5][6][7][8][9][10][11][12][13][14] Interestingly, experimentally determined CLTs greatly exceed the theoretical predictions. [5][6][7][8][9][10][11] Figure 1 summarizes the reported lattice relaxations in Al x Ga 1−x N/AlN (0001) heterostructures assessed by XRD reciprocal space mapping (RSM).…”

mentioning

confidence: 99%

Enhanced nonradiative recombination in Al_xGa_1−xN-based quantum wells thinner than the critical layer thickness determined by X-ray diffraction

Ichikawa¹,

Funato²,

Kawakami³

2021

Appl. Phys. Express

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The optical properties of Al x Ga1−x N-based quantum wells (QWs) with various thicknesses are investigated. When the Al x Ga1−x N thickness in Al0.8Ga0.2N/AlN QWs exceeds 6 nm, the photoluminescence lifetime is drastically shortened even at cryogenic temperatures, which indicates that nonradiative recombination processes are enhanced. Interestingly, the thicknesses for the degradation of the optical properties of Al x Ga1−x N on AlN (0001) are about two orders of magnitude thinner than the critical layer thicknesses for lattice relaxation determined by a conventional X-ray diffraction method. To avoid the degradation of the QW optical properties, Al y Ga1−y N (y > x) underlying layers are effective.

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“…The compressive stress is as large as 1.3-1.5 GPa, which can be calculated based on the Raman spectra and thermal expansion coefficient [82,83]. The excess compressive stress may cause the deterioration of surface morphology, unwanted wafer bowing, and severe composition pulling effects, which should be controlled in a proper range [84][85][86][87][88]. Additionally, impurities from the graphite susceptor and chamber are easily incorporated into the AlN epilayer at the annealing temperature.…”

Section: High Temperature Annealing (Hta)mentioning

confidence: 99%

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

Zhang

et al. 2021

Crystals

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Ultrawide bandgap (UWBG) semiconductor materials, with bandgaps far wider than the 3.4 eV of GaN, have attracted great attention recently. As a typical representative, wurtzite aluminum nitride (AlN) material has many advantages including high electron mobility, high breakdown voltage, high piezoelectric coefficient, high thermal conductivity, high hardness, high corrosion resistance, high chemical and thermal stability, high bulk acoustic wave velocity, prominent second-order optical nonlinearity, as well as excellent UV transparency. Therefore, it has wide application prospects in next-generation power electronic devices, energy-harvesting devices, acoustic devices, optical frequency comb, light-emitting diodes, photodetectors, and laser diodes. Due to the lack of low-cost, large-size, and high-ultraviolet-transparency native AlN substrate, however, heteroepitaxial AlN film grown on sapphire substrate is usually adopted to fabricate various devices. To realize high-performance AlN-based devices, we must first know how to obtain high-crystalline-quality and controllable AlN/sapphire templates. This review systematically summarizes the recent advances in fabricating wurtzite AlN film on (0001)-plane sapphire substrate. First, we discuss the control principles of AlN polarity, which greatly affects the surface morphology and crystalline quality of AlN, as well as the electronic and optoelectronic properties of AlN-based devices. Then, we introduce how to control threading dislocations and strain. The physical thoughts of some inspirational growth techniques are discussed in detail, and the threading dislocation density (TDD) values of AlN/sapphire grown by various growth techniques are compiled. We also introduce how to achieve high thermal conductivities in AlN films, which are comparable with those in bulk AlN. Finally, we summarize the future challenge of AlN films acting as templates and semiconductors. Due to the fast development of growth techniques and equipment, as well as the superior material properties, AlN will have wider industrial applications in the future.

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Effect of stress on the Al composition evolution in AlGaN grown using metal organic vapor phase epitaxy

Cited by 8 publications

References 27 publications

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Enhanced nonradiative recombination in Al_xGa_1−xN-based quantum wells thinner than the critical layer thickness determined by X-ray diffraction

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

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Effect of stress on the Al composition evolution in AlGaN grown using metal organic vapor phase epitaxy

Cited by 8 publications

References 27 publications

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Role of Strain-Induced Microscale Compositional Pulling on Optical Properties of High Al Content AlGaN Quantum Wells for Deep-Ultraviolet LED

Enhanced nonradiative recombination in Al x Ga1−x N-based quantum wells thinner than the critical layer thickness determined by X-ray diffraction

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

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Enhanced nonradiative recombination in Al_xGa_1−xN-based quantum wells thinner than the critical layer thickness determined by X-ray diffraction