High growth rate magnetron sputter epitaxy of GaN using a solid Ga target

Pingen, Katrin; Hinz, Alexander M.; Sandström, Per; Wolff, Niklas; Kienle, Lorenz; Scipioni, Larry; Greer, James; von Hauff, Elizabeth; Hultman, Lars; Birch, Jens; Hsiao, Ching-Lien

doi:10.1016/j.vacuum.2023.112852

Cited by 7 publications

(9 citation statements)

References 41 publications

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“…AlN/Si(111) templates with selected Al seed layer growth times are overgrown with GaN without a break in vacuum. GaN sputtering is carried out in a sputter-up configuration using an UHV-magnetron with bespoke cooling designed by PVD Product, Inc. enabling GaN MSE with a solid Ga target . GaN growth is performed at a total pressure of 0.4 Pa with a partial pressure ratio of N 2 /Ar of 0.3 at a growth temperature of 800 °C on a rotating substrate.…”

Section: Methodsmentioning

confidence: 99%

“…The analysis of the ELNES is in good agreement with literature data of AlN exemplifying the high-quality growth of the AlN nucleation layer. 12,48 In contrast, growing AlN on Si with preceding Al seeding (30 s) leads to the formation of a structurally mixed interlayer. The HAADF-STEM image presented in Figure 6a shows the growth of a ∼4 nm thin interlayer and a ∼45 nm AlN film with higher surface roughness.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Magnetron sputter epitaxy (MSE) is an emerging technology that offers many advantages for device-quality III-nitride growth: cost-effectiveness, high-throughput, and ease of scalability. Sputtering from a solid Ga target enables a stable process and high growth rates for producing high-quality GaN . Energetic ion bombardment enables lower growth temperatures leading to lower thermal stresses in the films and facilitates direct integration with Si complementary metal-oxide-semiconductor technology.…”

Section: Introductionmentioning

confidence: 99%

“…Sputtering from a solid Ga target enables a stable process and high growth rates for producing high-quality GaN. 12 Energetic ion bombardment enables lower growth temperatures leading to lower thermal stresses in the films and facilitates direct integration with Si complementary metal-oxide-semiconductor technology. The heteroepitaxial growth on cost-effective Si(111) substrates is the preferred choice for power electronic devices; however, GaN-on-Si epitaxy is characterized by large mismatches in lattice parameter and thermal expansion coefficient.…”

Section: Introductionmentioning

confidence: 99%

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III-Nitride Magnetron Sputter Epitaxy on Si: Controlling Morphology, Crystal Quality, and Polarity Using Al Seed Layers

Pingen,

Wolff,

Mohammadian

et al. 2024

ACS Appl. Mater. Interfaces

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Group III-nitride semiconductors have been subject of intensive research, resulting in the maturing of the material system and adoption of III-nitrides in modern optoelectronics and power electronic devices. Defined film polarity is an important aspect of III-nitride epitaxy as the polarity affects the design of electronic devices. Magnetron sputtering is a novel approach for cost-effective epitaxy of IIInitrides nearing the technological maturity needed for device production; therefore, control of film polarity is an important technological milestone. In this study, we show the impact of Al seeding on the AlN/Si interface and resulting changes in crystal quality, film morphology, and polarity of GaN/AlN stacks grown by magnetron sputter epitaxy. X-ray diffraction measurements demonstrate the improvement of the crystal quality of the AlN and subsequently the GaN film by the Al seeding. Nanoscale structural and chemical investigations using scanning transmission electron microscopy reveal the inversion of the AlN film polarity. It is proposed that N-polar growth induced by Al seeding is related to the formation of a polycrystalline oxygen-rich AlN interlayer partially capped by an atomically thin Si-rich layer at the AlN/Si interface. Complementary aqueous KOH etch studies of GaN/AlN stacks demonstrate that purely metal-polar and N-polar layers can be grown on a macroscopic scale by controlling the amount of Al seeding.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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III-Nitride Magnetron Sputter Epitaxy on Si: Controlling Morphology, Crystal Quality, and Polarity Using Al Seed Layers

Pingen,

Wolff,

Mohammadian

et al. 2024

ACS Appl. Mater. Interfaces

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“…However, the used Ga-targets need to be heavily cooled to remain solid during sputtering. 33) In addition, the cooling system gets more complex for larger wafer diameters. Alternatively, ceramic GaN targets can be used but are difficult to handle due to high impurity concentrations.…”

mentioning

confidence: 99%

Low-field transport properties and scattering mechanisms of degenerate n-GaN by sputtering from a liquid Ga target

Döring,

Tschirky

2024

Appl. Phys. Express

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In this work, degenerate n-type GaN thin films prepared by co-sputtering from a liquid Ga-target were demonstrated and their low field scattering mechanisms described. Extremely high donor concentrations above 3×1020 cm-3 at low process temperatures (< 800 °C) with specific resistivities below 0.5 mΩcm were achieved. The degenerate nature of the sputtered films was verified via temperature-dependent Hall-measurements (300-550 K) revealing negligible change in electron mobility and donor concentration. Scattering at ionized impurities was determined to be the major limiting factor with a minor contribution of polar optical-phonon scattering at high temperatures.

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