Low dislocation density AlN on sapphire prepared by double sputtering and annealing

Ding, Wanyu; Uesugi, Kenjiro; Xiao, Shengqiang; Norimatsu, Kenji; Miyake, Hideto

doi:10.35848/1882-0786/ababec

Cited by 34 publications

(36 citation statements)

References 34 publications

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“…High-temperature annealing has been proposed as an effective approach to improving the crystallinity of hBN and the crystal quality of AlN. [39][40][41][42] We have also performed high-temperature annealing at 1600 °C in the same MBE chamber for the hBN samples grown at lower temperatures. However, the morphology of hBN nanoribbons, as well as the above-mentioned BN nanoparticles, barely change, which is attributed to the robust thermal stability of BN.…”

Section: Interface-mediated Synthesis Of Monolayer Hbnmentioning

confidence: 99%

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

et al. 2022

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as fundamental building blocks of such 2D devices. Specifically, vertically stacked hBN/ graphene (hBN/G) van der Waals (vdW) heterostructures have been successfully employed to produce emergent properties, such as quantum Hall effect, [8] Hofstadter butterfly spectrum, [9] and plasmon and phonon polaritons. [10] Complementary to the vertical hBN/G vdW heterostructure, the in-plane version forms a covalent hBN/G heterostructure with equally attractive properties, such as transitions between semiconducting, half-metallic, and metallic phases, spin polarization magnetism, and exotic electronic states, [11][12][13][14][15] or even the possibility to reconstruct electronic interfaces similar to those observed in oxide heterostructures. [16,17] The scope of these fascinating properties could be radically expanded by demonstrating epitaxially grown monolayer hBN on graphene with superior structural, electrical, and optical properties, as well as precise control of both the hBN/G out-ofplane and in-plane monolayer interfaces.Recently, intensive efforts have been devoted to the epitaxial growth of hBN on metals, [18][19][20] sapphire, [21] and graphene substrates [22] by using sputtering, [23] chemical vapor deposition (CVD), [24] metal-organic chemical vapor deposition (MOCVD), [25] and molecular beam epitaxy (MBE). [26] Due to the Monolayer hexagonal boron nitride (hBN) has been widely considered a fundamental building block for 2D heterostructures and devices. However, the controlled and scalable synthesis of hBN and its 2D heterostructures has remained a daunting challenge. Here, an hBN/graphene (hBN/G) interface-mediated growth process for the controlled synthesis of high-quality monolayer hBN is proposed and further demonstrated. It is discovered that the in-plane hBN/G interface can be precisely controlled, enabling the scalable epitaxy of unidirectional monolayer hBN on graphene, which exhibits a uniform moiré superlattice consistent with single-domain hBN, aligned to the underlying graphene lattice. Furthermore, it is identified that the deep-ultraviolet emission at 6.12 eV stems from the 1s-exciton state of monolayer hBN with a giant renormalized direct bandgap on graphene. This work provides a viable path for the controlled synthesis of ultraclean, wafer-scale, atomically ordered 2D quantum materials, as well as the fabrication of 2D quantum electronic and optoelectronic devices.

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Section: Interface-mediated Synthesis Of Monolayer Hbnmentioning

confidence: 99%

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

et al. 2022

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“…To further reduce the TDD, the AlN buffer used for HTA needs to be thickened. Thus, a double sputtering and annealing process (Figure 15) was developed to fabricate 1.2 µm-thick AlN template, which can avoid tensile stress accumulation and decrease the probability of cracking [74]. Inspired by the thermal cycle annealing (TCA) method for reducing the TDDs in GaAs, Ge, and PbSe grown on Si, Ding Wang et al performed TCA on 800 nm-thick sputtered AlN buffer.…”

Section: High Temperature Annealing (Hta)mentioning

confidence: 99%

“…Thus, the AlN epilayer is nearly stress-free. [17,36,40,42,43,46,53,56,[58][59][60]62,69,73,74,76,79,81,94,[98][99][100][101][102][103][104][105][106][107][108][109] It is noted that there has been no unified standard for the evaluation of TDD. X-ray rocking curve (XRC) scan is the most common method to evaluate TDD.…”

Section: Quasi-van Der Waals Epitaxy (Qvdwe)mentioning

confidence: 99%

“…Cross-sectional TEM and plan-view TEM results can give the TDD of the top AlN layer, as shown in Figure 24. Nevertheless, they have certain degrees of randomness, since the measurement area is usually <50 µm 2 [17,53,74]. Planview cathodoluminescence (CL) spectroscopy, which is frequently used to count the TDD of GaN epilayer, is no longer applicable to AlN because of the poor conductivity of AlN and the weak responsivity of the detector at ~200 nm.…”

Section: Quasi-van Der Waals Epitaxy (Qvdwe)mentioning

confidence: 99%

“…Figure 23. Selected AlN/sapphire TDD by year of publication[17,36,40,42,43,46,53,56,[58][59][60]62,69,73,74,76,79,81,94,[98][99][100][101][102][103][104][105][106][107][108][109]. The ultralow TDD value of 3.4 × 10 7 cm −2 has been achieved by ELOG growth technique in 2006.…”

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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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Drive High Power UVC‐LED Wafer into Low‐Cost 4‐Inch Era: Effect of Strain Modulation

Liu

Yuan

Huang

et al. 2022

Adv Funct Materials

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Ultraviolet-C light-emitting diodes (UVC-LEDs) have great application in pathogen inactivation under various kinds of situations, especially in the fight against COVID-19. Unfortunately, its epitaxial wafers are so far limited to a size of 2 inches, which greatly increases the cost of massive production. In this work, a 4-inch crack-free high-power UVC-LED wafer is reported. This achievement relies on a proposed strain-tailored strategy, where a 3D to 2D (3D-2D) transition layer is introduced during the homo-epitaxy of AlN on the high temperature annealed (HTA)-AlN template, which successfully drives the original compressive strain into a tensile one and thus solves the challenge of realizing a high-quality Al 0.6 Ga 0.4 N layer with a flat surface. This smooth Al 0.6 Ga 0.4 N layer is nearly pseudomorphically grown on the strain-tailored HTA-AlN template, leading to 4-inch UVC-LED wafers with outstanding performances. The strategy succeeds in compromising the bottlenecked contradictory in producing a large-sized UVC-LED wafer on pronounced crystalline AlN template: The compressive strain in HTA-AlN allows for a crack-free 4-inch wafer, but at the same time leads to a deterioration of the AlGaN morphology and crystal quality. The launch of 4-inch wafers makes the chip fabrication process of UVC-LEDs match the mature blue one, and will definitely speed up the universal application of UVC-LED in daily life.

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Low dislocation density AlN on sapphire prepared by double sputtering and annealing

Cited by 34 publications

References 34 publications

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

Scalable Synthesis of Monolayer Hexagonal Boron Nitride on Graphene with Giant Bandgap Renormalization

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

Drive High Power UVC‐LED Wafer into Low‐Cost 4‐Inch Era: Effect of Strain Modulation

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