Metalorganic vapor phase epitaxy of GaN on 2 inch ScAlMgO<sub>4</sub> (0001) substrates

Fukui, Takato; Sakaguchi, Taro; Matsuda, Yoshinobu; Matsukura, Makoto; Kojima, Takahiro; Funato, Mitsuru; Kawakami, Yoichi

doi:10.35848/1347-4065/ac89c2

Cited by 12 publications

(16 citation statements)

References 28 publications

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“…Chemical–mechanical-polished, as-received substrates already showed well-defined surfaces with atomically smooth terraces and steps. Unlike our recent study, but similar to our earlier study, the step height in the present work was one-third of the c -lattice parameter of ScAlMgO 4 (∼0.8 nm). Therefore, the ScAlMgO 4 surface was covered with either the wurtzite phase (Mg,Al)O (0001) or the rocksalt phase ScO (111) .…”

Section: Methodssupporting

confidence: 85%

“…Although the lattice mismatch between GaN and ScAlMgO 4 is small, LT GaN buffer layers are considered to be necessary to obtain a high-quality GaN epilayer with an atomically smooth surface. ,,,,, (We have confirmed by the KOH solution etching method that the GaN epilayers are Ga-polar.) As shown later, one of the reasons LT GaN buffer layers are necessary is that they compensate for the poor wettability of GaN on ScAlMgO 4 under the growth conditions typically used in metal-organic vapor-phase epitaxy (MOVPE).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, a substrate material, ScAlMgO 4 , has attracted interest. − The c -plane lattice mismatch between GaN and ScAlMgO 4 is as small as 1.8%, which may lead to fewer threading dislocations. In addition, a smaller thermal expansion mismatch between GaN and ScAlMgO 4 than between GaN and sapphire suppresses wafer bowing, which facilitates device processes.…”

Section: Introductionmentioning

confidence: 99%

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Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Fukui

Matsuda

Matsukura

et al. 2023

Crystal Growth & Design

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GaN layers are grown on Al-pretreated ScAlMgO4 (0001) substrates by metal-organic vapor-phase epitaxy (MOVPE) without using low-temperature (LT) buffer layers. The Al pretreatment is performed under a H2 and N2 gas mixture and results in the nucleation of AlN on the ScAlMgO4. High-resolution transmission electron microscopy reveals that the ScAlMgO4 (0001) surface is terminated with the rocksalt phase ScO (111). Because of the chemical nature of the ScO layer, the AlN nuclei are N-polar. However, subsequent GaN MOVPE inverts the polarity to metal-polar in the vicinity of the boundary between the interfacial AlN nucleation layer and GaN layer, which is attributed to the GaN surface during MOVPE being more stable when it is metal-polar. The grown GaN layers exhibit better crystalline quality compared with GaN grown on ScAlMgO4 or sapphire (0001) substrates using conventional LT-buffer technology, thereby demonstrating the promise of the method to produce high-quality GaN epilayers on ScAlMgO4.

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Section: Methodssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Fukui

Matsuda

Matsukura

et al. 2023

Crystal Growth & Design

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“…Ohnishi [58] 等采用 AFM 对其表面的粗糙度进行测试，如图 11(h)。在 20×20 μm 2 的区域内，其平均粗糙度 (Ra)为 0.08 nm，表明通过刀片剥离的 SCAM 表面为原子级平面。因此，SCAM 衬底是生长高质量 GaN 外延薄膜的最佳选择 [48,[58][59][60] 。图 11 SCAM 衬底的再利用过程 [58] Fig. 11 SCAM substrate reuse process [58] (a [79][80][81][82] 。因此采用低温生长方法对于以 SCAM 为衬底获得高质量 GaN 薄膜至关重要。脉冲激光沉积(Pulsed Laser Deposition, PLD)技术采用脉冲激光烧蚀 GaN 靶材会导致在衬底表面迁移的前驱体具有较高的能量 [80,[83][84] ，使薄膜可以在较低的温度下进行外延生长。2016 年 Wang 等 [85] [85] Fig.…”

Section: Scam 原料合成unclassified

Research Progress of ScAlMgO₄ Crystal: a Novel GaN and ZnO Substrate

Chaoyi¹,

Tang²,

Xianke³

et al. 2023

Journal of Inorganic Materials

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Since the 21st century, the third generation of wide band gap (Eg>2.3 eV) semiconductor materials represented by gallium nitride (GaN) and zinc oxide (ZnO) are becoming the core supporting materials for the development of semiconductor industry. Due to the difficult growth and high cost of GaN and ZnO single crystal, epitaxial technology is always used to grow GaN and ZnO films on the substrate materials. It is crucial to find an ideal substrate material for the development of third generation semiconductor. Compared with traditional substrate materials, such as sapphire, 6H-SiC, and GaAs, scandium magnesium aluminate (ScAlMgO4) crystal, as a new self-peeling substrate material, has attracted much attention because of its smaller lattice mismatch (mismatch rate is ~1.4 % and ~0.09 %, respectively) and suitable thermal expansion coefficient with GaN and ZnO. In this paper, based on the structure of ScAlMgO4 crystal, the unique trigonal bipyramid coordination and natural superlattice structure are introduced in detail, which is the structural basis of its thermal and electrical properties. In addition, the layered structure of ScAlMgO4 crystal along the caxis makes it self-peeling, which greatly reduces its preparation cost and has a good application prospect in the preparation of self-supported GaN films. However, the raw material of ScAlMgO4 is difficult to synthesize, and the crystalgrowth method is single, mainly the czochralski method (Cz), and growing techniques lag far behind Japan. Therefore, it is urgent to develop a new growth method of growing high quality and large size ScAlMgO4 crystals to break the technical barriers.

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“…Moreover, the mismatch of the thermal expansion coefficients of SAM (5.59 Â 10 À6 K À1 ) [3,4] and GaN (3.34 Â 10 À6 K À1 ) [6] is 40%, which is %1/3 of that between sapphire and GaN. [3,4,7] These small mismatches are effective in suppressing wafer bowing [8] and the generation of cracks in the epilayer, compared to the extent of these issues when GaN is grown on sapphire substrates.…”

Section: Introductionmentioning

confidence: 99%

Substrate Terrace Width Dependence of Direct Growth of GaN on ScAlMgO₄ by Radio‐Frequency Molecular Beam Epitaxy

Wada

Deura

Kuroda

et al. 2023

Physica Status Solidi (b)

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ScAlMgO4 (SAM) substrates have attracted considerable attention as platforms for GaN growth in recent years because GaN can be grown directly on SAM without any buffer layer. Herein, the effect of the terrace width of SAM substrates on direct GaN growth is investigated using radio‐frequency molecular beam epitaxy (RF‐MBE). A flat and single wurtzite (WZ)‐phase GaN film is grown on a SAM substrate with a large terrace width. In contrast, a rough GaN film with a mixture of WZ and zinc‐blende (ZB) phases is obtained on SAM with a small terrace width. The SAM step height of 0.8 nm corresponds to three GaN molecular layers. Therefore, ZB stacking faults may be generated during the coalescence of islands located on adjacent terraces, although only the WZ‐GaN islands grow in the initial growth stage. This indicates that SAM substrates with a larger terrace width, that is, a smaller off‐cut angle, are preferable for obtaining a flat WZ‐GaN film.

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Metalorganic vapor phase epitaxy of GaN on 2 inch ScAlMgO₄ (0001) substrates

Cited by 12 publications

References 28 publications

Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Research Progress of ScAlMgO₄ Crystal: a Novel GaN and ZnO Substrate

Substrate Terrace Width Dependence of Direct Growth of GaN on ScAlMgO₄ by Radio‐Frequency Molecular Beam Epitaxy

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Metalorganic vapor phase epitaxy of GaN on 2 inch ScAlMgO4 (0001) substrates

Cited by 12 publications

References 28 publications

Interface formation mechanism of GaN on Al-pretreated ScAlMgO4 (0001) substrates

Interface formation mechanism of GaN on Al-pretreated ScAlMgO4 (0001) substrates

Research Progress of ScAlMgO4 Crystal: a Novel GaN and ZnO Substrate

Substrate Terrace Width Dependence of Direct Growth of GaN on ScAlMgO4 by Radio‐Frequency Molecular Beam Epitaxy

Contact Info

Product

Resources

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Metalorganic vapor phase epitaxy of GaN on 2 inch ScAlMgO₄ (0001) substrates

Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Interface formation mechanism of GaN on Al-pretreated ScAlMgO₄ (0001) substrates

Research Progress of ScAlMgO₄ Crystal: a Novel GaN and ZnO Substrate

Substrate Terrace Width Dependence of Direct Growth of GaN on ScAlMgO₄ by Radio‐Frequency Molecular Beam Epitaxy