Hole Scattering in p-type Wurtzite Gallium Nitride

2001 ◽  
Vol 680 ◽  
Author(s):  
J. D. Albrecht ◽  
P. P. Ruden
Keyword(s):  
Gallium Nitride ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Final States ◽  
Hamiltonian Description ◽  
Scattering Rate ◽  
Transverse Acoustic ◽  
Valence Bands ◽  
P Type ◽  
Strong Scattering

ABSTRACTWe investigate acoustic phonon scattering processes for holes in wurtzite gallium nitride. Using a six-band Rashba-Sheka-Pikus Hamiltonian description of the valence bands of gallium nitride, total scattering rates are calculated by numerical integration over final states. An examination of the interband and intraband processes shows strong scattering rate anisotropy between holes moving parallel to and perpendicular to the hexagonal plane. Results are given for inelastic acoustic deformation potential and piezoelectric scattering processes involving both longitudinal and transverse acoustic phonon absorption.

Carrier-Phonon Scattering Rate and Charge Transport in Spherical and TMV Nanometric Viruses

2010 ◽  
Vol 12 ◽  
pp. 65-76
Author(s):  
Sanjeev K. Gupta ◽  
Prafulla K. Jha
Keyword(s):  
Charge Transport ◽  
Molecular Electronics ◽  
Acoustic Phonon ◽  
Absorption Rate ◽  
Phonon Scattering ◽  
Phonon Energy ◽  
Hole Energy ◽  
Scattering Rate

The present paper presents the carrier-acoustic phonon scattering rate and charge transport in spherical and TMV viruses. We demonstrate theoretically that the absorption rate changes according to the phonon energy while emission of phonon is limited by the both electron and hole energy. The obtained conductivity for spherical and TMV viruses suggest that the TMV virus is more conducting and therefore may be a good candidate for the connector or wire to be used in the nano- and molecular- electronics . The value of resistance obtained for TMV virus is lower than the resistance of DNA.

scholarly journals Manipulation of Band Degeneracy and Lattice Strain for Extraordinary PbTe Thermoelectrics

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Yixuan Wu ◽  
Pengfei Nan ◽  
Zhiwei Chen ◽  
Zezhu Zeng ◽  
Siqi Lin ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Large Strain ◽  
X Ray Diffraction ◽  
Fine Control ◽  
Dispersion Measures ◽  
Valence Bands ◽  
Phonon Relaxation Time ◽  
P Type

Maximizing band degeneracy and minimizing phonon relaxation time are proven to be successful for advancing thermoelectrics. Alloying with monotellurides has been known to be an effective approach for converging the valence bands of PbTe for electronic improvements, while the lattice thermal conductivity of the materials remains available room for being further reduced. It is recently revealed that the broadening of phonon dispersion measures the strength of phonon scattering, and lattice dislocations are particularly effective sources for such broadening through lattice strain fluctuations. In this work, a fine control of MnTe and EuTe alloying enables a significant increase in density of electron states near the valence band edge of PbTe due to involvement of multiple transporting bands, while the creation of dense in-grain dislocations leads to an effective broadening in phonon dispersion for reduced phonon lifetime due to the large strain fluctuations of dislocations as confirmed by synchrotron X-ray diffraction. The synergy of both electronic and thermal improvements successfully leads the average thermoelectric figure of merit to be higher than that ever reported for p-type PbTe at working temperatures.

The Phonon Thermal Conductivity of a Single-Layer Graphene From Complete Phonon Dispersion Relations

2010 ◽  
Author(s):  
Yunfeng Gu ◽  
Zhonghua Ni ◽  
Minhua Chen ◽  
Kedong Bi ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Optical Phonons ◽  
Relaxation Rates ◽  
Phonon Thermal Conductivity ◽  
Transverse Acoustic

In this paper, the phonon scattering mechanisms of a single layer graphene are investigated based on the complete phonon dispersion relations. According to the selection rules that a phonon scattering process should obey the energy and momentum conservation conditions, the relaxation rates of combing and splitting Umklapp processes can be calculated by integrating the intersection lines between different phonon mode surfaces in the phonon dispersion relation space. The dependence of the relaxation rates on the wave vector directions is presented with a three dimensional surfaces over the first Brillion zone. It is found that the reason for the optical phonons contributing a little to heat transfer is attributed to the strong Umklapp processes but not to their low group velocities. The combing Umklapp scattering processes involved by the optical phonons mainly decrease the acoustic phonon thermal conductivity, while the splitting Umklapp scattering processes of the optical phonons mainly restrict heat conduction by the optical phonons themselves. Neglecting the splitting processes, the optical phonons can contribute more energy than that carried by the acoustic phonons. Based on the calculated phonon relaxation time, the thermal conductivities contributed from different mode phonons can be evaluated. At low temperatures, both longitudinal and in-plane transverse acoustic phonon thermal conductivities have T2 temperature dependence, and the out-of-plane transverse acoustic phonon thermal conductivity is proportion to T3/2. At room temperature, the calculated thermal conductivity is on the order of a few thousands W/m.K depending on the sample size and the edge roughness, which is in agreement with the recently measured data.

The Phonon Thermal Conductivity of Single-Layer Graphene From Complete Phonon Dispersion Relations

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Yunfeng Gu ◽  
Zhonghua Ni ◽  
Minhua Chen ◽  
Kedong Bi ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Optical Phonons ◽  
Relaxation Rates ◽  
Phonon Thermal Conductivity ◽  
Transverse Acoustic

In this paper, the phonon scattering mechanisms of single-layer graphene are investigated based on the complete phonon dispersion relations. According to the selection rules that a phonon scattering process should obey the energy and momentum conservation conditions, the relaxation rates of combining and splitting umklapp processes can be calculated by integrating the intersection lines between different phonon mode surfaces in the phonon dispersion relation space. The dependence of the relaxation rates on the wave vector directions is presented with a three-dimensional surface over the first Brillouin zone. It is found that the reason for the optical phonons contributing little to heat transfer is attributed to the strong umklapp processes but not to their low phonon group velocities. The combining umklapp scattering processes involving the optical phonons mainly decrease the acoustic phonon thermal conductivity, while the splitting umklapp scattering processes of the optical phonons mainly restrict heat conduction by the optical phonons themselves. Neglecting the splitting processes, the optical phonons can contribute more energy than that carried by the acoustic phonons. Based on the calculated phonon relaxation time, the thermal conductivities contributed from different mode phonons can be evaluated. At low temperatures, both longitudinal and in-plane transverse acoustic phonon thermal conductivities have T2 temperature dependence, and the out-of-plane transverse acoustic phonon thermal conductivity is proportion to T3/2. The calculated thermal conductivity is on the order of a few thousands W/(m K) at room temperature, depending on the sample size and the edge roughness, and is in agreement well with the recently measured data in the temperature range from about 350 K to 500 K.

Light-hole to heavy-hole acoustic phonon scattering rate

2000 ◽  
Vol 62 (12) ◽  
pp. 8114-8119 ◽  
Author(s):  
G. Sun ◽  
L. Friedman ◽  
R. A. Soref
Keyword(s):  
Acoustic Phonon ◽  
Heavy Hole ◽  
Phonon Scattering ◽  
Light Hole ◽  
Scattering Rate

Polar Optical Phonon Instability and Intervalley Transfer in Gallium Nitride

1998 ◽  
Vol 512 ◽  
Author(s):  
B. E. Foutz ◽  
S. K. O'leary ◽  
M. S. Shur ◽  
L. F. Eastman ◽  
B. L. Gelmont ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Analytical Model ◽  
Optical Phonon ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Polar Optical Phonon ◽  
Scattering Mechanism ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe develop a simple, one-dimensional, analytical model, which describes electron transport in gallium nitride. We focus on the polar optical phonon scattering mechanism, as this is the dominant energy loss mechanism at room temperature. Equating the power gained from the field with that lost through scattering, we demonstrate that beyond a critical electric field, 114 kV/cm at T = 300 K, the power gained from the field exceeds that lost due to polar optical phonon scattering. This polar optical phonon instability leads to a dramatic increase in the electron energy, this being responsible for the onset of intervalley transitions. The predictions of our analytical model are compared with those of Monte Carlo simulations, and are found to be in satisfactory agreement.

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