scholarly journals Photo-Induced Carrier Density, Optical Conductance and Transmittance in Graphene in the Presence of Optic-Phonon Scattering

10.5772/14328 ◽  
2011 ◽  
Author(s):  
W. Xu ◽  
H.M. Dong
Keyword(s):  
Carrier Density ◽  
Phonon Scattering ◽  
Optic Phonon

Achieving high carrier density and high mobility in graphene using monolayer tungsten oxyselenide

2021 ◽  
Author(s):  
Min Sup Choi ◽  
Ankur Nipane ◽  
Brian Kim ◽  
Mark Ziffer ◽  
Ipshita Datta ◽  
...  
Keyword(s):  
Carrier Density ◽  
Phonon Scattering ◽  
High Mobility ◽  
Transparent Conductors ◽  
Ring Resonators ◽  
Chemical Doping ◽  
Electrostatic Model ◽  
Hole Density ◽  
Phase Modulators ◽  
Doped Graphene

Abstract Highly doped graphene holds promise for next-generation electronic and photonic devices. However, chemical doping cannot be precisely controlled, and introduces external disorder that significantly diminishes the carrier mobility and therefore the graphene conductivity. Here, we show that monolayer tungsten oxyselenide (TOS) created by oxidation of WSe2 acts as an efficient and low-disorder hole-dopant for graphene. When the TOS is directly in contact with graphene, the induced hole density is 3 × 1013 cm-2 , and the room-temperature mobility is 2,000 cm2 /V·s, far exceeding that of chemically-doped graphene. Inserting WSe2 layers between the TOS and graphene tunes the induced hole density as well as reduces charge disorder such that the mobility exceeds 20,000 cm2 /V·s and reaches the limit set by acoustic phonon scattering, resulting in sheet resistance below 50 Ω/□. An electrostatic model based on work-function mismatch accurately describes the tuning of the carrier density with WSe2 interlayer thickness. These films show unparalleled performance as transparent conductors at telecommunication wavelengths, as shown by measurements of transmittance in thin films and insertion loss in photonic ring resonators. This work opens up new avenues in optoelectronics incorporating two-dimensional heterostructures including infrared transparent conductors, electro-phase modulators, and various junction devices.

scholarly journals Electron capture in GaAs quantum wells via electron‐electron and optic phonon scattering

1996 ◽  
Vol 68 (1) ◽  
pp. 117-119 ◽  
Author(s):  
K. Kálna ◽  
M. Moško ◽  
F. M. Peeters
Keyword(s):  
Quantum Wells ◽  
Electron Capture ◽  
Phonon Scattering ◽  
Optic Phonon

Polaron Effects and Optic Phonon Scattering in Heterostructures

1988 ◽  
pp. 243-269
Author(s):  
R. J. Nicholas ◽  
M. A. Hopkins ◽  
M. A. Brummell ◽  
D. R. Leadley
Keyword(s):  
Phonon Scattering ◽  
Optic Phonon

scholarly journals Giant isotope effect on phonon dispersion and thermal conductivity in methylammonium lead iodide

2020 ◽  
Vol 6 (31) ◽  
pp. eaaz1842
Author(s):  
M. E. Manley ◽  
K. Hong ◽  
P. Yin ◽  
S. Chi ◽  
Y. Cai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Phonon Scattering ◽  
Light Emission ◽  
Phonon Dispersion ◽  
Acoustic Phonons ◽  
Lead Iodide ◽  
Phonon Bottleneck ◽  
Optic Phonon ◽  
Methylammonium Lead Iodide

Lead halide perovskites are strong candidates for high-performance low-cost photovoltaics, light emission, and detection applications. A hot-phonon bottleneck effect significantly extends the cooling time of hot charge carriers, which thermalize through carrier–optic phonon scattering, followed by optic phonon decay to acoustic phonons and finally thermal conduction. To understand these processes, we adjust the lattice dynamics independently of electronics by changing isotopes. We show that doubling the mass of hydrogen in methylammonium lead iodide by replacing protons with deuterons causes a large 20 to 50% softening of the longitudinal acoustic phonons near zone boundaries, reduces thermal conductivity by ~50%, and slows carrier relaxation kinetics. Phonon softening is attributed to anticrossing with the slowed libration modes of the deuterated molecules and the reduced thermal conductivity to lowered phonon velocities. Our results reveal how tuning the organic molecule dynamics enables control of phonons important to thermal conductivity and the hot-phonon bottleneck.

scholarly journals Phonons and Quantum Criticality Revealed by Temperature Linear Resistivity in Twisted Double Bilayer Graphene

2021 ◽  
Author(s):  
Yanbang Chu ◽  
Le Liu ◽  
Cheng Shen ◽  
Jinpeng Tian ◽  
Jian Tang ◽  
...  
Keyword(s):  
Displacement Field ◽  
Single Particle ◽  
Carrier Density ◽  
Phonon Scattering ◽  
Twist Angle ◽  
Bilayer Graphene ◽  
Quantum Criticality ◽  
Van Hove Singularity ◽  
Scattering Model ◽  
Wide Range

Abstract Twisted double bilayer graphene (TDBG) is an electric-field-tunable moiré system, exhibiting electron correlated states and related temperature linear (T-linear) resistivity. The displacement field provides a new knob to in-situ tune the relative strength of electron interactions in TDBG, yielding not only a rich phase diagram but also the ability to investigate each phase individually. Here, we report a study of carrier density (n), displacement field (D) and twist angle (θ) dependence of T-linear resistivity in TDBG. For a large twist angle (θ > 1.5°) where correlated insulating states are absent, we observe a T-linear resistivity (order of 10Ω/K) over a wide range of carrier density and its slope decreases with increasing of n before reaching the van Hove singularity, in agreement with acoustic phonon scattering model. The slope of T-linear resistivity is non-monotonically dependent on displacement field, with a single peak structure closely connected to single-particle van Hove Singularity (vHS) in TDBG. For an optimal twist angle of ~ 1.23° in the presence of correlated states, the slope of T-linear resistivity is found maximum at the boundary of the correlated halo regime (order of 100Ω/K), resulting a ‘M’ shape displacement field dependence. The observation is beyond the phonon scattering model from single particle picture, and instead it suggests a strange metal behavior. We interpret the observation as a result of symmetry-breaking instability developed at quantum critical points where electron degeneracy changes. Our results demonstrate that TDBG is an ideal system to study the interplay between phonon and quantum criticality, and might help to map out the evolution of the order parameters for the ground states.

Acoustic phonon scattering in ultra-high mobility, low carrier density GaAs/(Al,Ga)As heterojunctions

1990 ◽  
Vol 229 (1-3) ◽  
pp. 113-115 ◽  
Author(s):  
J.J. Harris ◽  
C.T. Foxon ◽  
D. Hilton ◽  
J. Hewett ◽  
C. Roberts ◽  
...  
Keyword(s):  
Carrier Density ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
High Mobility
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