Twinned growth of ScN thin films on lattice-matched GaN substrates

Acharya, Shashidhara; Chatterjee, Abhijit; Bhatia, Vijay K.; Pillai, Ashalatha Indiradevi Kamalasanan; Garbrecht, Magnus; Saha, Bivas

doi:10.1016/j.materresbull.2021.111443

Cited by 12 publications

(7 citation statements)

References 44 publications

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“…Since ScN(111) is lattice-matched with GaN(0001), ScN interlayers have been extensively researched to reduce dislocation densities in GaN epilayers. , As metallic TMNs (such as TiN, ZrN, HfN) exhibit the same rocksalt crystal structure and similar lattice parameters as ScN, epitaxial (Zr,Hf)N/ScN metal/semiconductor superlattices are developed for thermionic emission applications. − Wurtzite Al 1– x Sc x N exhibits a high c -axis piezoelectric coefficient and is actively researched for engineering bulk and surface acoustic devices . However, due to its promising thermoelectric properties, ScN is much desired in recent times.…”

Section: Introductionmentioning

confidence: 99%

Multifunctional Irradiation-Induced Defects for Enhancing Thermoelectric Properties of Scandium Nitride Thin Films

Rao

Chowdhury

Pillai

et al. 2022

ACS Appl. Energy Mater.

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Scandium nitride (ScN) is an emerging rocksalt indirect bandgap semiconductor with the potential to overcome some of the limitations of traditional wurtzite III (A)-nitride semiconductors in next-generation optoelectronic and thermoelectric applications. Epitaxial ScN thin films contain point defects such as oxygen impurities that result in a high carrier concentration and help achieve a high thermoelectric power factor. However, due to its high thermal conductivity, the thermoelectric figure-of-merit (zT) of ScN is relatively low. Recent theoretical calculations have suggested that scandium and nitrogen vacancies in ScN introduce asymmetric states close to the Fermi energy, increasing its Seebeck coefficient. Increased phonon scattering by these native defects should also reduce thermal conductivity to help achieve higher zT. However, incorporating such native defects in as-deposited ScN is challenging due to their high formation energies. In this work, we introduce native defects in molecular beam epitaxy (MBE)-deposited ScN thin films by lithium-ion irradiation and study the impact of such native defects on ScN’s thermoelectric properties. Consistent with theoretical calculations, we find that the Seebeck coefficient in irradiated ScN thin films increases significantly. Thermal conductivity decreases by more than half to 7 ± 1 W/(m·K) at room temperature due to phonon scattering by the irradiation-induced defects. Despite a reduced electrical conductivity due to scattering from defects, irradiated ScN thin films exhibit a high power factor ∼(1–2) × 10–3 W/(m·K2) in the 300–950 K range and show a modest increase in the overall zT. This work highlights the multifunctionality of irradiation-induced defects in engineering thermoelectric properties of transition metal nitride semiconductors.

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Section: Introductionmentioning

confidence: 99%

Multifunctional Irradiation-Induced Defects for Enhancing Thermoelectric Properties of Scandium Nitride Thin Films

Rao

Chowdhury

Pillai

et al. 2022

ACS Appl. Energy Mater.

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“…Scandium nitride (ScN) is an emerging group-III(B) rocksalt indirect band gap semiconductor 16 and has attracted much attention for its high thermoelectric power factor, 17 as a seed layer for defect-free GaN growth, 18 and epitaxial metal/ semiconductor superlattice development. 19 Like most other transition metal nitrides, ScN is mechanically hard (∼24 GPa.…”

mentioning

confidence: 99%

Reversal of Band-Ordering Leads to High Hole Mobility in Strained p-type Scandium Nitride

Rudra,

Rao,

Poncé

et al. 2023

Nano Lett.

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“…ScN is a rocksalt group-III (B) semiconducting transition-metal-nitride (TMN) and exhibits corrosion-resistant high hardness, high melting temperature (∼2600 °C) and is stable at ambient temperature and pressure. − Because of the degenerate semiconducting nature with a direct bandgap of 2.2 eV and indirect gap of 0.9 eV, − ScN has attracted significant interest in recent years for thermoelectric energy conversion . Lattice-matched (111) ScN seed-layers are also utilized to reduce the dislocation densities in (0002) GaN epilayers for light-emitting diodes. , As-deposited ScN thin films exhibit an n -type carrier concentration of (2–4) × 10 20 cm –3 primarily because of the presence of oxygen impurities and exhibit a mobility in the 60–90 cm 2 /(V s) range. Because of such high carrier concentrations, the Fermi level in ScN resides inside the conduction band, about 0.2–0.3 eV inside the conduction band minima .…”

mentioning

confidence: 99%

“…While the present work utilizes (001) MgO as a substrate with the same crystal structure, it must be mentioned that ScN films are regularly deposited on industrially important Al 2 O 3 and Si substrates that should provide seamless chip integration. In addition, because of its near-perfect lattice-matching, (111) ScN films have been deposited on (0001) GaN with very little defects , that would also lead to its integration with GaN-based light-emission and power electronic applications.…”

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confidence: 99%

“…42 Lattice-matched (111) ScN seed-layers are also utilized to reduce the dislocation densities in (0002) GaN epilayers for light-emitting diodes. 43,44 As-deposited ScN thin films exhibit an n-type carrier concentration of (2−4) × 10 20 cm −3 primarily because of the presence of oxygen impurities and exhibit a mobility in the 60−90 cm 2 /(V s) range. Because of such high carrier concentrations, the Fermi level in ScN resides inside the conduction band, about 0.2−0.3 eV inside the conduction band minima.…”

mentioning

confidence: 99%

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Polar Semiconducting Scandium Nitride as an Infrared Plasmon and Phonon–Polaritonic Material

et al. 2022

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The interaction of light with collective charge oscillations, called plasmon–polariton, and with polar lattice vibrations, called phonon–polariton, are essential for confining light at deep subwavelength dimensions and achieving strong resonances. Traditionally, doped-semiconductors and conducting metal oxides (CMO) are used to achieve plasmon–polaritons in the near-to-mid infrared (IR), while polar dielectrics are utilized for realizing phonon–polaritons in the long-wavelength IR (LWIR) spectral regions. However, demonstrating low-loss plasmon– and phonon–polaritons in one host material will make it attractive for practical applications. Here, we demonstrate high-quality tunable short-wavelength IR (SWIR) plasmon–polariton and LWIR phonon–polariton in complementary metal-oxide-semiconductor compatible group III–V polar semiconducting scandium nitride (ScN) thin films. We achieve both resonances by utilizing n-type (oxygen) and p-type (magnesium) doping in ScN that allows modulation of carrier concentration from 5 × 1018 to 1.6 × 1021 cm–3. Our work enables infrared nanophotonics with an epitaxial group III semiconducting nitride, opening the possibility for practical applications.

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Twinned growth of ScN thin films on lattice-matched GaN substrates

Cited by 12 publications

References 44 publications

Multifunctional Irradiation-Induced Defects for Enhancing Thermoelectric Properties of Scandium Nitride Thin Films

Multifunctional Irradiation-Induced Defects for Enhancing Thermoelectric Properties of Scandium Nitride Thin Films

Reversal of Band-Ordering Leads to High Hole Mobility in Strained p-type Scandium Nitride

Polar Semiconducting Scandium Nitride as an Infrared Plasmon and Phonon–Polaritonic Material

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