Antimonene and bismuthene are promising members of the 2D pnictogen family with their tunable band gaps, high electronic conductivity, and ambient stability, making them suitable for electronic and optoelectronic applications. However, semi‐metal to semiconductor transition occurs only in the mono/bilayer regime, limiting their applications. Covalent functionalization is a versatile method for tuning materials’ chemical, electronic, and optical properties and can be explored for tuning the properties of pnictogens. In this work, emissions in liquid exfoliated antimonene and bismuthene are observed at ≈2.23 and ≈2.33 eV, respectively. Covalent functionalization of antimonene and bismuthene with p‐nitrobenzene diazonium salt proceeds with the transfer of lone pairs from Sb/Bi to the diazonium salt, introducing organic moieties on the surface attached predominantly via Sb/BiC bonds. Consequently, Sb/Bi signatures in Raman and X‐ray photoelectron spectra are blue‐shifted, implying lattice distortion and charge transfer. Interestingly, emission can be tailored upon functionalization to 2.18 and 2.27 eV for antimonene and bismuthene respectively, and this opens the possibility of tuning the properties of pnictogens and related materials. This is the first report on covalent functionalization of antimonene and bismuthene. It sheds light on the reaction mechanism on pnictogen surfaces and demonstrates tunability of optical property and surface passivation.
Scandium nitride (ScN) is an emerging rock salt indirect bandgap semiconductor and has attracted significant interest in recent years for thermoelectric energy conversion, as a substrate for defect-free GaN growth, as a semiconducting component in single-crystalline metal/semiconductor superlattices for thermionic energy conversion, as well as for Al1−xScxN-based bulk and surface acoustic devices for 5G technologies. Most ScN film growth traditionally utilizes physical vapor deposition techniques such as magnetron sputtering and molecular beam epitaxy, which results in stoichiometric films but with varying crystal quality, orientations, microstructures, and physical properties. As epitaxial single-crystalline ScN films with smooth surfaces are essential for device applications, it is important to understand the ScN growth modes and parameters that impact and control their microstructure. In this Letter, we demonstrate that large adatom mobility is essential to overcome the Ehrlich–Schwoebel (E–S) and grain boundary migration barriers and achieve defect (voids, dislocations, stacking faults, etc.)-free single-crystalline ScN films. Using the substrate temperature to tune adatom mobility, we show that nominally single-crystalline ScN films are achieved when the homologous temperature is higher than ∼0.3. For homologous temperatures ranging from 0.23 to 0.30, ScN films are found to exhibit significant structural voids in between pyramidal growth regions with multiple in-plane orientations resulting from additional lateral growth off the facets of the pyramids and broken epitaxy after ∼80 nm of growth. The in-depth discussion of the growth modes of ScN presented here explains its varying electrical and optical properties and will help achieve high-quality ScN for device applications.
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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