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

Rudra, Sourav; Rao, Dheemahi; Poncé, Samuel; Saha, Bivas

doi:10.1021/acs.nanolett.3c02350

Cited by 7 publications

(1 citation statement)

References 48 publications

(81 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such features in the N K -edge spectrum are associated with the transition from the core N 1s level to antibonding N 2 ps – Mg 3 ps hybridized states. Theoretically calculated density of states (DOS) shows that the valence band edge near the Fermi-level is mostly dominated by N 2p states, similar to other nitrides, ,, and conduction band states appear from the hybridization of N 2p, 2s and Mg 3s, 3p orbitals. , The peak A (∼404.9 eV) at the edge onset is assigned to the N 1s π* transition, and the prominent B peak (∼410.9 eV) corresponds to the N 1s σ* transition . Such antibonding states originate through N 2ps – Mg 3ps hybridized states.…”

Section: Results and Discussionmentioning

confidence: 91%

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films

Shukla,

Rudra,

Karanje

et al. 2024

Chem. Mater.

Self Cite

View full text Add to dashboard Cite

Excitons are the lowest excited state of the electronic subsystem in semiconductors, composed of a bound electron−hole pair interacting via screened coulomb potential. Compared to the band-to-band transitions, excitons exhibit stronger luminescence with greater oscillator strength at low temperatures. However, achieving room-temperature excitonic luminescence in semiconductors is challenging due to their low binding energies. Magnesium nitride (Mg 3 N 2 ), an emerging IInitride semiconductor, hosts a room-temperature excitonic luminescence in the visible spectral range in the powder phase. Here, we show conclusive experimental evidence of strain-induced valence band splitting in epitaxial and stoichiometric Mg 3 N 2 thin films that leads to excitonic luminescence above and below its direct bandgap at room temperature. Growth-induced biaxial tensile strain splits the light hole and split-off hole bands in Mg 3 N 2 by ∼170 meV, which causes the above-bandgap luminescence. Optical absorption, synchrotron radiation ultraviolet photoemission spectroscopy, and photoluminescence measurements also confirm that Mg 3 N 2 is a direct bandgap semiconductor with an exciton binding energy of ∼40 meV. First-principles calculations with Heyd−Scuseria−Ernzerhof hybrid-functional support the straininduced valence band splitting and above-bandgap excitonic feature. Room-temperature multiple exciton luminescence in Mg 3 N 2 would be useful for visible-light-emitting diodes (LEDs), semiconductor lasers, and other optoelectronic applications.

show abstract

Section: Results and Discussionmentioning

confidence: 91%

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films

Shukla,

Rudra,

Karanje

et al. 2024

Chem. Mater.

Self Cite

View full text Add to dashboard Cite

show abstract

Thermionic Emission in Artificially Structured Single‐Crystalline Elemental Metal/Compound Semiconductor Superlattices

Rawat,

Rao,

Rudra

et al. 2024

Advanced Materials

View full text Add to dashboard Cite

Metal/semiconductor superlattices represent a fascinating frontier in materials science and nanotechnology, where alternating layers of metals and semiconductors are precisely engineered at the atomic and nano‐scales. Traditionally, epitaxial metal/semiconductor superlattice growth requires constituent materials from the same family, exhibiting identical structural symmetry and low lattice mismatch. Here, beyond this conventional constraint, a novel class of epitaxial lattice‐matched metal/semiconductor superlattices is introduced that utilizes refractory hexagonal elemental transition metals and wide‐bandgap III‐nitride semiconductors. Exemplified by the Hf/AlN superlattices exhibiting coherent layer‐by‐layer epitaxial growth, cross‐plane thermionic emission is observed through current–voltage measurements accomplished for the first time in any metal/semiconductor superlattices. Further, thermoreflectance measurements reveal significant enhancement in cross‐plane Seebeck coefficients attributed to carrier energy filtering by Schottky barriers. Demonstration of artificially structured elemental‐metal/wide‐bandgap compound‐semiconductor superlattices promises to usher in new fundamental physics studies and cutting‐edge applications such as tunable hyperbolic metamaterials, quantum computing, and thermionic‐emission‐based thermoelectric and thermophotonic energy conversion devices.

show abstract

Giant Enhancement of Hole Mobility for 4H-Silicon Carbide through Suppressing Interband Electron–Phonon Scattering

Sun,

Li,

Tong

et al. 2024

Nano Lett.

View full text Add to dashboard Cite

4H-silicon carbide (4H-SiC) possesses a high Baliga figure of merit, making it a promising material for power electronics. However, its applications are limited by low hole mobility. Herein, we found that the hole mobility of 4H-SiC is mainly limited by the strong interband electron–phonon scattering using mode-level first-principles calculations. Our research indicates that applying compressive strain can reverse the sign of crystal-field splitting and change the ordering of electron bands close to the valence band maximum. Therefore, the interband electron–phonon scattering is severely suppressed and the electron group velocity is significantly increased. The out-of-plane hole mobility of 4H-SiC can be greatly enhanced by ∼200% with 2% uniaxial compressive strain applied. This work provides new insights into the electron transport mechanisms in semiconductors and suggests a strategy to improve hole mobility that could be applied to other semiconductors with hexagonal crystalline geometries.

show abstract

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

Cited by 7 publications

References 48 publications

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films

Thermionic Emission in Artificially Structured Single‐Crystalline Elemental Metal/Compound Semiconductor Superlattices

Giant Enhancement of Hole Mobility for 4H-Silicon Carbide through Suppressing Interband Electron–Phonon Scattering

Contact Info

Product

Resources

About

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

Cited by 7 publications

References 48 publications

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg3N2 Thin Films

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg3N2 Thin Films

Thermionic Emission in Artificially Structured Single‐Crystalline Elemental Metal/Compound Semiconductor Superlattices

Giant Enhancement of Hole Mobility for 4H-Silicon Carbide through Suppressing Interband Electron–Phonon Scattering

Contact Info

Product

Resources

About

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films

Strain-Induced Valence Band Splitting Enabling Above-Bandgap Exciton Luminescence in Epitaxial Mg₃N₂ Thin Films