Intrinsic Thermal Conductivity of Wurtzite AlxGa1-xN, InxGa1-xN and InxAl1-xN From First-Principles Calculation

The thermal conductivities of the alloys of wurtzite AlN, GaN and InN are usually analyzed with the virtual crystal model based on the values of the constituent compounds. However, latest experiments and calculations reveal that the thermal conductivity of wurtzite InN is about three times larger than the previously used value. Thus it is necessary to reanalyze the thermal conductivities of these alloys. In this work, the intrinsic thermal conductivities of AlxGa1−xN, InxGa1−xN and InxAl1−xN are calculated with first-principles calculations along with the virtual crystal treatment. It is found that the thermal conductivities of these alloys are strongly suppressed even after a small amount of alloying. For instance, the in-plane and out-of-plane thermal conductivities of In0.99Ga0.01 N are 66 Wm−1K−1 and 76 Wm−1K−1 respectively, while they are 40 Wm−1K−1 and 48 Wm−1 K−1 for In0.99Al0.01 N, compared with the corresponding values of 130 Wm−1 K−1 and 145 Wm−1 K−1 for bulk wurtzite InN. When the fraction x varies from 0.2 to 0.8, the thermal conductivities of the alloys do not change much. Additionally, the distribution of mean free path indicates that the size effect can persist up to 10μm for both pure compounds and their alloys at room temperature.

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Built-in-polarization field effect on intrinsic and extrinsic thermal conductivities of AlN/GaN/AlN quantum well

International Journal of Modern Physics B ◽

10.1142/s0217979215501490 ◽

2015 ◽

Vol 29 (21) ◽

pp. 1550149 ◽

Cited By ~ 2

Author(s):

A. Pansari ◽

V. Gedam ◽

B. K. Sahoo

Keyword(s):

Thermal Conductivity ◽

Relaxation Time ◽

Quantum Well ◽

Room Temperature ◽

Mean Free Path ◽

Polarization Field ◽

Polarization Mechanism ◽

Negative Effect ◽

Phonon Velocity ◽

Thermal Conductivities

In this paper, the effect of built-in-polarization field on lattice thermal conductivity of AlN/GaN/AlN quantum well (QW) has been theoretically investigated. The built-in-polarization field at the hetero-interface of GaN/AlN modifies elastic constant, phonon velocity and Debye temperature of GaN QW. The relaxation time of acoustic phonons (AP) in various scattering processes in GaN with and without built-in-polarization field has been computed at room temperature. The result shows that combined relaxation time of AP is enhanced by built-in-polarization field and implies a longer mean free path. The revised intrinsic and extrinsic thermal conductivities of GaN have been estimated. The theoretical analysis shows that up to a certain temperature the polarization field acts as negative effect and reduces the thermal conductivities. However, after this temperature both thermal conductivities are significantly contributed by polarization field. This gives the idea of temperature dependence of polarization effect which signifies the pyro-electric character of GaN. The intrinsic thermal conductivity at room temperature for with and without polarization mechanism is found to be 491 Wm -1 K -1 and 409 Wm -1 K -1, respectively i.e., 20% enhancement. However, the extrinsic thermal conductivity at room temperature for with and without polarization mechanism is found to be 280 Wm -1 K -1 and 245 Wm -1 K -1, respectively i.e., 13% enhancement. The method we have developed may be taken into account during the simulation of heat transport in optoelectronic nitride devices to minimize the self-heating processes and in polarization engineering strategies to optimize the thermoelectric performance of GaN alloys.

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Where Should We Look For High Zt Materials: Suggestions From Theory.

MRS Proceedings ◽

10.1557/proc-626-z6.3 ◽

2000 ◽

Vol 626 ◽

Cited By ~ 1

Author(s):

M. Fornari ◽

D. J. Singh ◽

I. I. Mazin ◽

J. L. Feldman

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

First Principles ◽

Room Temperature ◽

First Principles Calculations ◽

High Electrical Conductivity ◽

Bulk Materials ◽

Low Thermal Conductivity ◽

Computational Exploration ◽

Single Material

ABSTRACTThe key challenges in discovering new high ZT thermoelectrics are understanding how the nearly contradictory requirements of high electrical conductivity, high thermopower and low thermal conductivity can be achieved in a single material and based on this identifying suitable compounds. First principles calculations provide a material specific microscopic window into the relevant properties and their origins. We illustrate the utility of the approach by presenting specific examples of compounds belonging to the class of skutterudites that are or are not good thermoelectrics along with the microscopic reasons. Based on our computational exploration we make a suggestion for achieving higher values of ZT at room temperature in bulk materials, namely n-type La(Ru,Rh)4Sb12 with high La-filling.

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Disparate strain response of the thermal transport properties of bilayer penta-graphene as compared to that of monolayer penta-graphene

Physical Chemistry Chemical Physics ◽

10.1039/c9cp02574j ◽

2019 ◽

Vol 21 (28) ◽

pp. 15647-15655 ◽

Cited By ~ 5

Author(s):

Zhehao Sun ◽

Kunpeng Yuan ◽

Xiaoliang Zhang ◽

Guangzhao Qin ◽

Xiaojing Gong ◽

...

Keyword(s):

Thermal Conductivity ◽

Transport Equation ◽

First Principles ◽

Room Temperature ◽

Lattice Thermal Conductivity ◽

Boltzmann Transport Equation ◽

Strain Response ◽

First Principles Calculations ◽

Boltzmann Transport ◽

Strain Modulation

In this study, strain modulation of the lattice thermal conductivity of monolayer and bilayer penta-graphene (PG) at room temperature was investigated using first-principles calculations combined with the phonon Boltzmann transport equation.

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Thermal conductivity of hexagonal BC2P – a first-principles study

RSC Advances ◽

10.1039/d0ra08444a ◽

2020 ◽

Vol 10 (70) ◽

pp. 42628-42632

Author(s):

Rajmohan Muthaiah ◽

Fatema Tarannum ◽

Roshan Sameer Annam ◽

Avinash Singh Nayal ◽

Swapneel Danayat ◽

...

Keyword(s):

Thermal Conductivity ◽

First Principles ◽

Room Temperature ◽

High Thermal Conductivity ◽

First Principles Calculations ◽

First Principles Study

In this work, we report a high thermal conductivity (k) of 162 W m−1 K−1 and 52 W m−1 K−1 at room temperature, along the directions perpendicular and parallel to the c-axis, respectively, of bulk hexagonal BC2P (h-BC2P), using first-principles calculations.

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Ultralow lattice thermal conductivity at room temperature in 2D KCuSe from first-principles calculations

Physical Chemistry Chemical Physics ◽

10.1039/d1cp04657h ◽

2021 ◽

Author(s):

Zhiyuan Xu ◽

Cong Wang ◽

Xuming Wu ◽

Lei Hu ◽

Yuqi Liu ◽

...

Keyword(s):

Thermal Conductivity ◽

First Principles ◽

Figure Of Merit ◽

Room Temperature ◽

Lattice Thermal Conductivity ◽

Transport Theory ◽

First Principles Calculations ◽

Boltzmann Transport ◽

Thermoelectric Figure ◽

Boltzmann Transport Theory

Ultralow lattice thermal conductivity is crucial to achieve a high thermoelectric figure of merit for thermoelectric applications. In this work, using the first-principles and phonon Boltzmann transport theory, we investigate...

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Magnetic order and critical temperature of substitutionally doped transition metal dichalcogenide monolayers

npj 2D Materials and Applications ◽

10.1038/s41699-021-00233-0 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Sabyasachi Tiwari ◽

Maarten L. Van de Put ◽

Bart Sorée ◽

William G. Vandenberghe

Keyword(s):

Transition Metal ◽

First Principles ◽

Room Temperature ◽

Magnetic Order ◽

Transition Metal Dichalcogenide ◽

First Principles Calculations ◽

Out Of Plane ◽

Atomic Substitution ◽

Mn Doped ◽

Ordered State

AbstractUsing first-principles calculations, we investigate the magnetic order in two-dimensional (2D) transition-metal-dichalcogenide (TMD) monolayers: MoS2, MoSe2, MoTe2, WSe2, and WS2 substitutionally doped with period four transition-metals (Ti, V, Cr, Mn, Fe, Co, Ni). We uncover five distinct magnetically ordered states among the 35 distinct TMD-dopant pairs: the non-magnetic (NM), the ferromagnetic with out-of-plane spin polarization (Z FM), the out-of-plane polarized clustered FMs (clustered Z FM), the in-plane polarized FMs (X–Y FM), and the anti-ferromagnetic (AFM) state. Ni and Ti dopants result in an NM state for all considered TMDs, while Cr dopants result in an anti-ferromagnetically ordered state for all the TMDs. Most remarkably, we find that Fe, Mn, Co, and V result in an FM ordered state for all the TMDs, except for MoTe2. Finally, we show that V-doped MoSe2 and WSe2, and Mn-doped MoS2, are the most suitable candidates for realizing a room-temperature FM at a 16–18% atomic substitution.

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First principles calculations of the structural, electronic, magnetic, and thermodynamic properties of the Nd2MgGe2 and Gd2MgGe2 intermetallic compounds

Scientific Reports ◽

10.1038/s41598-021-89042-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

S. Menouer ◽

O. Miloud Abid ◽

A. Benzair ◽

A. Yakoubi ◽

H. Khachai ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermodynamic Properties ◽

Ground State ◽

First Principles ◽

Essential Role ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Rare Earth Compounds ◽

First Principles Calculations ◽

Antiferromagnetic Ground State

AbstractIn recent years the intermetallic ternary RE2MgGe2 (RE = rare earth) compounds attract interest in a variety of technological areas. We therefore investigate in the present work the structural, electronic, magnetic, and thermodynamic properties of Nd2MgGe2 and Gd2MgGe2. Spin–orbit coupling is found to play an essential role in realizing the antiferromagnetic ground state observed in experiments. Both materials show metallicity and application of a Debye-Slater model demonstrates low thermal conductivity and little effects of the RE atom on the thermodynamic behavior.

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