9 research outputs found
-factor engineering with InAsSb alloys toward zero band gap limit
Band gap is known as an effective parameter for tuning the Lande -factor
in semiconductors and can be manipulated in a wide range through the bowing
effect in ternary alloys. In this work, using the recently developed virtual
substrate technique, high-quality InAsSb alloys throughout the whole Sb
composition range are fabricated and a large -factor of at
the minimum band gap of eV, which is almost twice that in bulk InSb
is found. Further analysis to the zero gap limit reveals a possible gigantic
-factor of with a peculiar relativistic Zeeman effect that
disperses as the square root of magnetic field. Such a -factor enhancement
toward the narrow gap limit cannot be quantitatively described by the
conventional Roth formula, as the orbital interaction effect between the nearly
triply degenerated bands becomes the dominant source for the Zeeman splitting.
These results may provide new insights into realizing large -factors and
spin polarized states in semiconductors and topological materials
GaSb-Based Type I Quantum-Well Light-Emitting Diode Addressable Array Operated at Wavelengths Up to 3.66 m
This basic research into mid-IR LEDs as an emitter array combines the advantages of high brightness, high dynamic range, uniformity, temperature stability, fast modulation (high frame rate), low cost, and high reliability. Type II interband cascade (IC) LEDs operating in the spectral range 3-5 m were successfully used for array fabrication The Type I mid-IR GaSb-based LED with a quantum-well active region has demonstrated high output power and internal efficienc
Giant -factors and fully spin-polarized states in metamorphic short-period InAsSb/InSb superlattices
Realizing a large Land\'{e} -factor of electrons in solid-state materials
has long been thought of as a rewarding task as it can trigger abundant
immediate applications in spintronics and quantum computing. Here, by using
metamorphic InAsSb/InSb superlattices (SLs), we demonstrate an unprecedented
high value of , twice larger than that in bulk InSb, and fully
spin-polarized states at low magnetic fields. In addition, we show that the
-factor can be tuned on demand from 20 to 110 via varying the SL period. The
key ingredients of such a wide tunability are the wavefunction mixing and
overlap between the electron and hole states, which have drawn little attention
in prior studies. Our work not only establishes metamorphic InAsSb/InSb as a
promising and competitive material platform for future quantum devices but also
provides a new route toward -factor engineering in semiconductor structures
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Quantum cascade lasers with electrically tunable emission wavelengths
The present invention provides a QCL device with an electrically controlled refractive index through the Stark effect. By changing the electric field in the active area, the energy spacing between the lasing energy levels may be changed and, hence, the effective refractive index in the spectral region near the laser wavelength may be controlled.Board of Regents, University of Texas Syste
Engineering Dirac Materials: Metamorphic InAs<sub>1–<i>x</i></sub>Sb<sub><i>x</i></sub>/InAs<sub>1–<i>y</i></sub>Sb<sub><i>y</i></sub> Superlattices with Ultralow Bandgap
Quasiparticles
with Dirac-type dispersion can be observed in nearly
gapless bulk semiconductors alloys in which the bandgap is controlled
through the material composition. We demonstrate that the Dirac dispersion
can be realized in short-period InAs<sub>1–<i>x</i></sub>Sb<sub><i>x</i></sub>/InAs<sub>1–<i>y</i></sub>Sb<sub><i>y</i></sub> metamorphic superlattices with
the bandgap tuned to zero by adjusting the superlattice period and
layer strain. The new material has anisotropic carrier dispersion:
the carrier energy associated with the in-plane motion is proportional
to the wave vector and characterized by the Fermi velocity <i>v</i><sub>F</sub>, and the dispersion corresponding to the motion
in the growth direction is quadratic. Experimental estimate of the
Fermi velocity gives <i>v</i><sub>F</sub> = 6.7 × 10<sup>5</sup> m/s. Remarkably, the Fermi velocity in this system can be
controlled by varying the overlap between electron and hole states
in the superlattice. Extreme design flexibility makes the short-period
metamorphic InAs<sub>1–<i>x</i></sub>Sb<sub><i>x</i></sub>/InAs<sub>1–<i>y</i></sub>Sb<sub><i>y</i></sub> superlattice a new prospective platform
for studying the effects of charge-carrier chirality and topologically
nontrivial states in structures with the inverted bandgaps