Thermal conductivity of GaN films: Effects of impurities and dislocations

Zou, Jiao; Kotchetkov, D.; Balandin, Alexander A.; Florescu, D. I.; Pollak, Fred H.

doi:10.1063/1.1497704

Cited by 304 publications

(221 citation statements)

References 26 publications

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“…For all calculations in this work, the dislocation density is set to 1 Â 10 9 cm À2 , which is high, but a typical dislocation density for GaN on sapphire. 37 …”

Section: Electron Transport Modelmentioning

confidence: 99%

“…The specific details of the treatment for each of these dislocation types in the gallium nitride system are described in detail by Zou et al 37 The material parameters and constants used in this work are given in Tables I and II. For alloy compositions, all values were extrapolated linearly between the two binary materials, 1,20 except where specific composition dependence relationships are available, as is the case for Debye temperature 39 and the elastic constants. 39 …”

Section: Phonon Transport Modelmentioning

confidence: 99%

See 1 more Smart Citation

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Sztein

Haberstroh

Bowers

et al. 2013

Journal of Applied Physics

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The thermoelectric properties of III-nitride materials are of interest due to their potential use for high temperature power generation applications and the increasing commercial importance of the material system; however, the very large parameter space of different alloy compositions, carrier densities, and range of operating temperatures makes a complete experimental exploration of this material system difficult. In order to predict thermoelectric performances and identify the most promising compositions and carrier densities, the thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN are modeled. The Boltzmann transport equation is used to calculate the Seebeck coefficient, electrical conductivity, and the electron component of thermal conductivity. Scattering mechanisms considered for electronic properties include ionized impurity, alloy potential, polar optical phonon, deformation potential, piezoelectric, and charged dislocation scattering. The Callaway model is used to calculate the phonon component of thermal conductivity with Normal, Umklapp, mass defect, and dislocation scattering mechanisms included. Thermal and electrical results are combined to calculate ZT values. InxGa1−xN is identified as the most promising of the three ternary alloys investigated, with a calculated ZT of 0.85 at 1200 K for In0.1Ga0.9N at an optimized carrier density. AlxGa1−xN is predicted to have a ZT of 0.57 at 1200 K under optimized composition and carrier density. InxAl1−xN is predicted to have a ZT of 0.33 at 1200 K at optimized composition and carrier density. Calculated Seebeck coefficients, electrical conductivities, thermal conductivities, and ZTs are compared with experimental data where such data are available.

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“…For all calculations in this work, the dislocation density is set to 1 Â 10 9 cm À2 , which is high, but a typical dislocation density for GaN on sapphire. 37 …”

Section: Electron Transport Modelmentioning

confidence: 99%

Section: Phonon Transport Modelmentioning

confidence: 99%

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Sztein

Haberstroh

Bowers

et al. 2013

Journal of Applied Physics

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show abstract

“…Various thermal management solutions, for example, flip-chip bonding 4 or diamond composite substrates 5, have been attempted. However, the hotspots, which appear due to the non-uniform dissipation of the high-power densities and relatively high thermal resistance of the substrates 6,7 , still limit practical applications of the nitride-based technology [1][2][3] . For example, AlGaN/GaN heterostructure field-effect transistors (HFETs) are attractive devices for high-frequency high-power communications and radar applications 1,2,8 .…”

mentioning

confidence: 99%

Graphene quilts for thermal management of high-power GaN transistors

et al. 2012

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self-heating is a severe problem for high-power gallium nitride (Gan) electronic and optoelectronic devices. Various thermal management solutions, for example, flip-chip bonding or composite substrates, have been attempted. However, temperature rise due to dissipated heat still limits applications of the nitride-based technology. Here we show that thermal management of Gan transistors can be substantially improved via introduction of alternative heat-escaping channels implemented with few-layer graphene-an excellent heat conductor. The graphene-graphite quilts were formed on top of AlGan/Gan transistors on siC substrates. using micro-Raman spectroscopy for in situ monitoring we demonstrated that temperature of the hotspots can be lowered by ~20 °C in transistors operating at ~13 W mm − 1 , which corresponds to an order-of-magnitude increase in the device lifetime. The simulations indicate that graphene quilts perform even better in Gan devices on sapphire substrates. The proposed local heat spreading with materials that preserve their thermal properties at nanometre scale represents a transformative change in thermal management.

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“…[18][19][20] Taking into account that the accepted value for the thermal conductivity of the GaN epilayer used in typical GaN devices is $160 W m À1 K À1 , the mean free path of phonons calculated through the kinetic expression for GaN is 278 nm and 410 nm using the lower and higher sound velocities, respectively. Introducing these values for K B into Eq.…”

mentioning

confidence: 99%

AlGaN/GaN field effect transistors for power electronics—Effect of finite GaN layer thickness on thermal characteristics

Hodges

Calvo

Stoffels

et al. 2013

Applied Physics Letters

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AlGaN/GaN heterostructure field effect transistors with a 150 nm thick GaN channel within stacked AlxGa1−xN layers were investigated using Raman thermography. By fitting a thermal simulation to the measured temperatures, the thermal conductivity of the GaN channel was determined to be 60 W m−1 K−1, over 50% less than typical GaN epilayers, causing an increased peak channel temperature. This agrees with a nanoscale model. A low thermal conductivity AlGaN buffer means the GaN spreads heat; its properties are important for device thermal characteristics. When designing power devices with thin GaN layers, as well as electrical considerations, the reduced channel thermal conductivity must be considered.

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Thermal conductivity of GaN films: Effects of impurities and dislocations

Cited by 304 publications

References 26 publications

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Graphene quilts for thermal management of high-power GaN transistors

AlGaN/GaN field effect transistors for power electronics—Effect of finite GaN layer thickness on thermal characteristics

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