Metal Organic Vapor Phase Epitaxy Chemical Kinetics

Kuech, T. F.

doi:10.1016/b978-0-444-63304-0.00021-4

Cited by 8 publications

(5 citation statements)

References 156 publications

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“…The pathway leading to the epitaxial growth is shown by the solid arrows. In this pathway, TMG decomposes into smaller units such as dimethylgallium (Ga(CH 3 ) 2 ) and monomethylgallium (GaCH 3 ) already in the gas phase. ,, As these species diffuse toward the substrate, their further decomposition leads to the formation of clusters of Ga. In parallel, NH 3 dissociates on the substrate, forming NH x ( x = 0–2) and H radicals. , These radicals recombine with the Ga clusters (and/or DMG/TMG) on the substrate.…”

Section: Gan Mocvd From Tmg and Nh3mentioning

confidence: 99%

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

et al. 2019

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We report the successful preparation of polycrystalline gallium nitride (poly-GaN) layers by thermal atomic layer deposition (ALD) at low temperatures (375−425°C) from trimethylgallium (TMG) and ammonia (NH 3 ) precursors. The growth per cycle (GPC) is found to be strongly dependent on the NH 3 pulse duration and the NH 3 partial pressure. The pressure dependence makes the ALD atypical. We propose that the ALD involves (i) the reversible formation of the hithertounreported TMG:NH 3 surface adduct, resulting from NH 3 physisorbing on a TMG surface site and (ii) the irreversible conversion of neighboring surface adducts to Ga−NH 2 −Ga linkages. The pressure dependence arises from the presumed reversible nature of the adduct formation on the surface, equivalent to the known reversible nature of its formation in the gas phase in metal organic chemical vapor deposition reactions. Using in situ spectroscopic ellipsometry (SE), the GPC monitored as a function of several ALD parameters is as high as 0.1 nm/cycle at 60 s NH 3 pulse and 1.3 mbar NH 3 partial pressure. The changes in the growth pattern (as monitored by SE) caused by changes in the ALD parameters support the proposed growth model. Ex situ characterization reveals that the layer is carbon-free, has a polycystalline wurtzitic structure, and shows a decent conformaility over Si trenches. Tuning the ALD recipe allows us to vary the layer composition from Ga-rich to stoichiometric GaN. The Ga richness is attributed to the simultaneous TMG dissociation at the deposition temperatures. This work is the first full-scale report on low temperature thermal ALD of poly-GaN from industrial precursors, occurring via a novel chemical pathway and not requiring any radical assistance (such as plasma) as used before.

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Section: Gan Mocvd From Tmg and Nh3mentioning

confidence: 99%

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

et al. 2019

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“…Epitaxy, on the other hand, describes the process involving the deposition of a material possessing one crystal type on a substrate with identical or almost identical lattice dimensions. [ 48 ] Thus, epitaxial solidification involves a solid grain or nucleus nucleation process from a liquid in contact with a substrate. [ 38 ] The partial remelting or the complete melt‐back of the substrate (i.e., previously deposited underlying or adjacent tracks and layers) facilitates epitaxial solidification.…”

Section: Texture Evolutionmentioning

confidence: 99%

Controlled Crystallographic Texture Orientation in Structural Materials Using the Laser Powder Bed Fusion Process—A Review

Cobbinah,

Matsunaga,

Yamabe-Mitarai

2023

Adv Eng Mater

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Advantages of the laser powder bed fusion (LPBF) process over conventional processing methods include microstructural control capability and complex geometry parts fabrication. For most alloys, the microstructure‐property relationship typically guides the LPBF process toward achieving application‐specific properties. Nonetheless, the LPBF process produces a high degree of anisotropy, primarily from the epitaxial preferred grain growth mechanisms during solidification and the consequent highly textured microstructures produced. The crystallographic texture‐controlled build concept through the LPBF process is a material design and processing approach gaining a lot of interest because of the promising unique and superior properties offered by the anisotropy accompanying the LPBF process. The numerous attempts at intentional texture‐controlled building or parts fabrication from structural materials using the LPBF process warrant an up‐to‐date review. Thus, this review presents solidification mechanisms that influence texture evolution during the LPBF process such as the melting mode, melt pool shape, influence of thermal gradient, and solidification rate. Furthermore, this review delves into the influence of LPBF process parameters on texture, accompanying microstructural evolution, and the intentional control of texture effects on properties such as mechanical, corrosion, and oxidation resistance.This article is protected by copyright. All rights reserved.

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“…The mass flux to the substrate surface is balanced by molecule incorporation into grown layer, as local thermodynamic equilibrium can be established in the vicinity of the growth interface [7]. This can be formulated by a combination of Fick's first law and Langmuir adsorption model (2) [6] − (D∇ϕ)…”

Section: Introductionmentioning

confidence: 99%

Growth Uniformity in Selective Area Epitaxy of AlGaN/GaN Heterostructures for the Application in Semiconductor Devices

et al. 2020

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The design of modern semiconductor devices often requires the fabrication of three-dimensional (3D) structures to integrate microelectronic components with photonic, micromechanical, or sensor systems within one semiconductor substrate. It is a technologically challenging task, as a strictly defined profile of the device structure is obligatory. This can be achieved either by chemical etching or selective deposition on a masked substrate. In this paper, the growth uniformity of AlGaN/GaN heterostructures during selective-area metalorganic vapour-phase epitaxy (SA-MOVPE) was studied. Such structures are typically used in order to fabricate high-electron-mobility transistors (HEMT). The semiconductor material was deposited through 200 μm long stripe-shaped open windows in a SiO2 mask on GaN/sapphire templates. The window width was varied from 5 μm to 160 μm, whereas mask width separating particular windows varied from 5 μm to 40 μm. The experiment was repeated for three samples differing in GaN layer thickness: 150 nm, 250 nm, and 500 nm. Based on theoretical models of the selective growth, a sufficiently uniform thickness of epitaxially grown AlGaN/GaN heterostructure has been achieved by selecting the window half-width that is smaller than the diffusion length of the precursor molecules. A Ga diffusion length of 15 μm was experimentally extracted by measuring the epitaxial material agglomeration in windows in the dielectric mask. Measurements were conducted while using optical profilometry.

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Metal Organic Vapor Phase Epitaxy Chemical Kinetics

Cited by 8 publications

References 156 publications

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

Thermal Atomic Layer Deposition of Polycrystalline Gallium Nitride

Controlled Crystallographic Texture Orientation in Structural Materials Using the Laser Powder Bed Fusion Process—A Review

Growth Uniformity in Selective Area Epitaxy of AlGaN/GaN Heterostructures for the Application in Semiconductor Devices

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