The intrinsic free carrier mobility in AlGaN/GaN quantum wells

2004 ◽  
Vol 831 ◽  
Author(s):  
F. Carosella ◽  
M. Germain ◽  
J.-L. Farvacque
Keyword(s):  
Quantum Wells ◽  
Carrier Mobility ◽  
Electron System ◽  
Relaxation Mechanism ◽  
Free Carrier ◽  
Free Carriers ◽  
Scattering Mechanisms ◽  
Carrier Interaction ◽  
Scattering Strength ◽  
Two Bodies

ABSTRACTThe aim of this contribution is to determine theoretically the maximum mobility that can be expected in AlGaN/GaN quantum wells as soon as the free carriers are only submitted to intrinsic scattering mechanisms associated with phonons and the carrier-carrier interaction. In our model, we consider that the carrier-carrier two bodies collisions do not constitute by themselves a relaxation mechanism since they conserve the momentum and the energy of the electron system. Thus, we assume that the free carriers act only through their contribution to the dynamical dielectric response of the material and, at least, through their collective behavior resulting into plasmons which, when damped, constitute now a real relaxation mechanism. The full scattering strength is connected with the imaginary part of the total reversed dielectric function including the lattice and the free carrier contributions. This approach automatically includes the scattering mechanisms associated with hybrid phonon/plasmon particles.

Phonons and Free Carriers in a Strained Hexagonal GaN-AlN Superlattice Measured by Infrared Ellipsometry and Raman Spectroscopy

1999 ◽  
Vol 595 ◽  
Author(s):  
M. Schubert ◽  
A. Kasic ◽  
T.E. Tiwald ◽  
J.A. Woollam ◽  
V. Harle ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Free Carrier ◽  
Phonon Modes ◽  
Lateral Mobility ◽  
Free Carriers ◽  
Organic Vapor ◽  
Infrared Ellipsometry ◽  
Order Of Magnitude ◽  
Metal Organic ◽  
Vertical Mobility

AbstractPhonon and free-carrier effects in a strained hexagonal (α) {GaN}l-{AlN}m superlattice (SL) heterostructure (l = 8 nm, m = 3 nm) are studied by infrared spectroscopic ellipsometry (IRSE) and micro (µ)-Raman scattering. Growth of the heterostructures was performed by metal-organic vapor phase epitaxy (MOVPE) on (0001) sapphire. An unstrained 1 µm-thick α-GaN layer was deposited prior to the SL. SL phonon modes are identified combining results from both IRSE and µ-Raman techniques. The shift of the GaN-sublayer phonon modes is used to estimate an average compressive SL stress of σxx ∼ - 4.3 GPa. The IRSE data reveal a free-carrier concentration of ne ∼ 5×1018 cm−3 within the undoped SL GaN-sublayers. According to the vertical carrier confinement, the free-carrier mobility is anisotropic, and the lateral mobility ( µ⊥ ∼ 400 cm2/Vs, polarization E⊥c-axis) exceeds the vertical mobility (µ∥ ∼ 24 cm2/Vs, E∥c) by one order of magnitude.

scholarly journals Phonons and Free Carriers in a Strained Hexagonal GaN-AlN Superlattice Measured by Infrared Ellipsometry and Raman Spectroscopy

2000 ◽  
Vol 5 (S1) ◽  
pp. 710-716 ◽  
Author(s):  
M. Schubert ◽  
A. Kasic ◽  
T.E. Tiwald ◽  
J.A. Woollam ◽  
V. Härle ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Free Carrier ◽  
Phonon Modes ◽  
Lateral Mobility ◽  
Free Carriers ◽  
Organic Vapor ◽  
Infrared Ellipsometry ◽  
Order Of Magnitude ◽  
Metal Organic ◽  
Vertical Mobility

Phonon and free-carrier effects in a strained hexagonal (α) {GaN}l-{AlN}msuperlattice (SL) heterostructure (l = 8 nm, m = 3 nm) are studied by infrared spectroscopic ellipsometry (IRSE) and micro (µ)-Raman scattering. Growth of the heterostructures was performed by metal-organic vapor phase epitaxy (MOVPE) on (0001) sapphire. An unstrained 1 µm-thick α-GaN layer was deposited prior to the SL. SL phonon modes are identified combining results from both IRSE and µ-Raman techniques. The shift of the GaN-sublayer phonon modes is used to estimate an average compressive SL stress of σxx ∼ - 4.3 GPa. The IRSE data reveal a free-carrier concentration of ne ∼ 5×1018 cm−3 within the undoped SL GaN-sublayers. According to the vertical carrier confinement, the free-carrier mobility is anisotropic, and the lateral mobility (µ⊥ ∼ 400 cm2/Vs, polarization E⊥c-axis) exceeds the vertical mobility (µ|| ∼ 24 cm2/Vs, E||c) by one order of magnitude.

Free carrier mobility in AlGaN/GaN quantum wells

2002 ◽  
Vol 14 (48) ◽  
pp. 13319-13328 ◽  
Author(s):  
J-L Farvacque ◽  
Z Bougrioua ◽  
F Carosella ◽  
I Moerman
Keyword(s):  
Quantum Wells ◽  
Carrier Mobility ◽  
Free Carrier

ELECTRICAL AND OPTICAL PROPERTIES OF MULTILAYER SOL GEL ZnO COATINGS

2006 ◽  
Vol 20 (23) ◽  
pp. 3357-3364 ◽  
Author(s):  
TALAAT MOUSSA HAMMAD
Keyword(s):  
Carrier Mobility ◽  
Sol Gel ◽  
Dip Coating ◽  
Free Carrier ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Electrical And Optical Properties ◽  
Zinc Oxide Films ◽  
Free Carrier Density ◽  
Fine Microstructure

Multilayer transparent conducting zinc oxide films have been prepared on boro-silicate substrates by the commercially sol gel dip coating process. Each layer was fired at 550°C in a conventional furnace for 15 min. The final coatings were then tempered under a flux of forming gas ( N 2/ H 2) at 400°C for 2 h. The coatings were characterized by surface stylus profiling and optical spectroscopy (UV-NIR). Results show that (1) ZnO films with electrical resistivity of 6×10-4 Ω· cm , free carrier mobility of approximately 77 cm 2/ V · s and free carrier density of approximately 6.14×1019 cm -3 are obtained for multilayers 310 nm and (2) the transmittance is approximately 60.4% and the reflectance is nearly 34.7% are obtained at a wavelength of 800 nm when the thickness of the ZnO multilayers is 310 nm. The crystal structure and grain orientation of ZnO films were determined by X-ray diffraction. SEM investigations revealed that the surface morphology of growing ZnO films on boro-silicate substrate is dominated by the smooth surface with a fine microstructure.

scholarly journals Dynamics of Strong Coupling Between Free Charge Carriers in Organometal Halide Perovskites and Aluminum Plasmonic States

2022 ◽  
Vol 9 ◽  
Author(s):  
Yang Luo ◽  
Hai Wang ◽  
Le-Yi Zhao ◽  
Yong-Lai Zhang
Keyword(s):  
Strong Coupling ◽  
Transient Absorption ◽  
Perovskite Solar Cells ◽  
Coupled System ◽  
Free Carrier ◽  
Charge Carriers ◽  
Free Charge ◽  
Free Carriers ◽  
Halide Perovskites ◽  
Poor Absorption

We have investigated a strong coupled system composed of a MAPbIxCl3-x perovskite film and aluminum conical nanopits array. The hybrid states formed by surface plasmons and free carriers, rather than the traditional excitons, is observed in both steady-state reflection measurements and transient absorption spectra. In particular, under near upper band resonant excitation, the bleaching signal from the band edge of uncoupled perovskite was completely separated into two distinctive bleaching signals of the hybrid system, which is clear evidence for the formation of strong coupling states between the free carrier–plasmon state. Besides this, a Rabi splitting up to 260 meV is achieved. The appearance of the lower bands can compensate for the poor absorption of the perovskite in the NIR region. Finally, we found that the lifetime of the free carrier–SP hybrid states is slightly shorter than that of uncoupled perovskite film, which can be caused by the ultrafast damping of the SPs modes. These peculiar features on the strong coupled hybrid states based on free charge carriers can open new perspectives for novel plasmonic perovskite solar cells.

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