(Invited) Rare Earth Materials for Semiconductor Applications

Elshocht, Sven Van; Adelmann, Christoph; Popovici, M.; Swerts, Johan; Delabie, Annelies; Nyns, L.; Shi, Xiaoping; Tielens, Hilde; Brijs, Bert; Pourtois, Geoffrey; Schram, T.; Pierreux, Dieter; Maes, Jan; Hardy, An; Bael, Marlies K. Van; Kittl, J. A.

doi:10.1149/1.3375598

Cited by 4 publications

(3 citation statements)

References 28 publications

(36 reference statements)

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“…In parallel, the deposition was very nonuniform with WiWNU values on the order of 100%. This is in consistent with previous reports, which found a CVD-like growth behavior for Gd 2 O 3 and Gd-rich ternary alloys. ,, …”

Section: Resultssupporting

confidence: 94%

Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O

et al. 2014

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The reaction chemistry during the atomic layer deposition (ALD) of Sc2O3 and Gd2O3 from Sc(MeCp)3, Gd(iPrCp)3, and H2O was investigated by in situ time-resolved quadrupole mass spectrometry. Despite the similarity of the ligands of the Sc and Gd precursors, the growth characteristics and ligand dissociation patterns of the Sc2O3 and Gd2O3 ALD processes showed considerably different behavior. For both processes, the precursors reacted with the hydroxylated surface by proton transfer and release of the protonated ligand. The remaining ligands were then removed by hydrolysis during the H2O pulse. However, for the Sc(MeCp)3/H2O process, ∼56% of MeCpH was released during the Sc(MeCp)3 exposure, whereas in the case of the Gd(iPrCp)3/H2O process, as much as 90% of iPrCpH was released during the Gd(iPrCp)3 pulse. The observation that almost all iPrCp ligands were removed during the initial Gd(iPrCp)3 absorption step can be ascribed to CVD-like reactions between the Gd(iPrCp)3 precursor and excess hydroxide or physisorbed H2O on the hygroscopic Gd2O3 surface. The influence of the growth temperature on the ligand exchange behavior and the resulting film properties (thickness uniformity, impurity concentration) was studied in the temperature range between 200 and 350 °C. In addition, the transient growth behavior of Gd2O3 on Sc2O3 and vice versa was studied, indicating that the hygroscopic nature of Gd2O3 also strongly influences the deposition of Gd x Sc1–x O3 ternary oxides.

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Section: Resultssupporting

confidence: 94%

Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O

et al. 2014

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“…An increased gate leakage after annealing at temperatures >200 °C suggests that some challenges in terms of interface stability still remain. One possible reason for such an instability might be the hygroscopic nature of the GAO dielectric. , This is supported by the measured capacitance-equivalent thickness (CET) of 2.4 nm, which may indicate that the permittivity was affected by water absorption. Capping of the layer in situ may therefore be essential.…”

Section: Resultsmentioning

confidence: 94%

Amorphous Gadolinium Aluminate as a Dielectric and Sulfur for Indium Phosphide Passivation

Dorp

Nyns

Cuypers

et al. 2019

ACS Appl. Electron. Mater.

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The passivation of n-type InP (100) using sulfur in combination with a gadolinium aluminate (GAO) dielectric layer has been studied. Photoluminescence, minority-carrier lifetime, and capacitance–voltage measurements indicate that a (NH4)2S vapor passivation step prior to atomic layer deposition of the oxide effectively lowers the interface state density. Surface and interface chemistry were studied by synchrotron radiation photoemission spectroscopy (SRPES). The effect of ex situ surface passivation after native oxide removal in HCl solution was examined. It was observed that surface reoxidation occurred during (NH4)2S vapor exposure, leading to the formation of In x (HPO4) y . S was present on the surface as a sulfide in both surface and subsurface sites. After atomic layer deposition of GAO, sulfates were detected in addition to In x (HPO4) y , which was confirmed by near-edge X-ray absorption fine structure analysis. The S in the stack was quantified using reference-free grazing incidence X-ray fluorescence analysis. X-ray absorption spectroscopy showed that Gd was oxidized and present in the 3+ oxidation state, most likely as a phosphate close to the InP interface and possibly mixed with sulfates. Energy-dependent SRPES measurements of Al 2p and Gd 4d core levels, complemented by transmission electron microscopy, further suggest that the dielectric layer was segregated. Valence band measurements confirm the effective passivation of InP, indicating unpinning of the surface Fermi level.

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“…Gadolinium aluminate (Gd x Al 2– x O 3 ) is a promising candidate. In the amorphous phase, it has a similar κ-value (∼16) as HfO 2 and a band gap of ∼6 eV when x = 1 . In addition, Gd is reported to segregate near the insulator/semiconductor interface during the GdAlO 3 ALD on the InP substrate, possibly due to the higher reactivity of Gd( i PrCp) 3 .…”

Section: Introductionmentioning

confidence: 99%

Top-Gate Stack Engineering Featuring a High-κ Gadolinium Aluminate Interfacial Layer for Field-Effect Transistors Based on Two-Dimensional Transition-Metal Dichalcogenides

Lin,

Wu,

Cott

et al. 2024

ACS Appl. Electron. Mater.

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Atomic layer deposition (ALD) of gate dielectrics on two-dimensional transition-metal dichalcogenides (2D TMDs) is challenging due to their chemically inert surfaces. Although various surface pretreatments can form nucleation sites to facilitate the precursor adsorption, preserving 2D TMDs during the pretreatments and maintaining gate stack quality with the weak 2D TMD/dielectric interface become the main concerns. In this work, we combine physisorbed-precursor-assisted (PPA)-ALD to minimize damage to 2D TMDs with a second interfacial layer for performance enhancement. Ultrathin GdAlO 3 interlayers are integrated into 2D TMD gate stacks with PPA-ALD AlO x seeding layers and HfO 2 top dielectrics. Further, 1-nm-thick and pinholefree GdAlO 3 can be deposited on AlO x -seeded monolayer (1L) WS 2 by ALD at 250 °C. The material properties of 1L WS 2 are preserved, as confirmed by Raman spectroscopy. After the GdAlO 3 layer insertion, 1L MoS 2 dual-gate (DG) field-effect transistors (FETs) show improved subthreshold swing (SS), field-effect mobility, and I d −V g hysteresis without compromising the capacitance-equivalent thickness (CET). The proposed strategy is waferscale compatible and extendable to the future nanosheet gate-all-around structures. KEYWORDS: molybdenum disulfide (MoS 2 ), tungsten disulfide (WS 2 ), atomic layer deposition (ALD), gadolinium aluminate, high-κ dielectrics, field-effect transistor

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(Invited) Rare Earth Materials for Semiconductor Applications

Cited by 4 publications

References 28 publications

Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O

Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O

Amorphous Gadolinium Aluminate as a Dielectric and Sulfur for Indium Phosphide Passivation

Top-Gate Stack Engineering Featuring a High-κ Gadolinium Aluminate Interfacial Layer for Field-Effect Transistors Based on Two-Dimensional Transition-Metal Dichalcogenides

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(Invited) Rare Earth Materials for Semiconductor Applications

Cited by 4 publications

References 28 publications

Reaction Chemistry during the Atomic Layer Deposition of Sc2O3 and Gd2O3 from Sc(MeCp)3, Gd(iPrCp)3, and H2O

Reaction Chemistry during the Atomic Layer Deposition of Sc2O3 and Gd2O3 from Sc(MeCp)3, Gd(iPrCp)3, and H2O

Amorphous Gadolinium Aluminate as a Dielectric and Sulfur for Indium Phosphide Passivation

Top-Gate Stack Engineering Featuring a High-κ Gadolinium Aluminate Interfacial Layer for Field-Effect Transistors Based on Two-Dimensional Transition-Metal Dichalcogenides

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Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O

Reaction Chemistry during the Atomic Layer Deposition of Sc₂O₃ and Gd₂O₃ from Sc(MeCp)₃, Gd(ⁱPrCp)₃, and H₂O