Nanoscale size dependence parameters on lattice thermal conductivity of Wurtzite GaN nanowires

Phonon Scatterings in the Lattice Thermal Conductivity of Si_(1-x) Ge_x Alloy Nanowires: Theoretical Study

“…A detailed explanation of this effect can be found in previous work of GaN NWs [44] and Si NWs [46]. But a difference between previous work and present work is that while the specularity parameter depends on the size of GaN and Si NWs, in Si 1-x Ge x alloy NWs this depends on the alloy concentration, as shown in figure 2 ( the role of parameters will be discussed later).…”

“…The constant parameters used in the calculations are listed in Table 1. Using an adjustable parameter, which is usual in the literature [41][42][43][44], attempts were made to use the three parameters, θ , γ and P , as adjustable parameters to correlate the calculated LTC to that of the corresponding experimental data at [21]. The values of θ , γ and P were adjusted such that the best fit for calculated LTC to the experimental data was obtained.…”

“…The values of θ , γ and P were adjusted such that the best fit for calculated LTC to the experimental data was obtained. In the calculations, the electron-phonon scattering rate was assumed (tested) to be as in our previous work [44] and the results changed by less than 2%, accordingly, this scattering rate was neglected. The high surface-to-volume ratio of semiconductor NWs can dramatically alter their fundamental properties with respect to corresponding bulk samples [45].…”

“…Phonon confinement (which reduces phonon group velocity), however, can lead to considerable reductions of LTC in 147 nm Theoritical 147 nm Expt.data [21] 344 nm Theoritical 344 nm Expt.data [21] 229 nm Theoritical 229 nm Expt.data [21] 160 nm Theoritical 160 nm Expt.data [21] Soran Mohammed Mamand: Phonon Scatterings in the Lattice Thermal Conductivity of Si 1-x Ge x Alloy Nanowires: Theoretical Study NWs [25,45]. For the aforementioned sample of Si 1-x Ge x alloy NWs, phonon group velocities are assumed to be sizedependent (as a result of phonon confinement) and calculated using a thermodynamical approach, as used in previous work [44], with all the parameters of Si and Ge available at [46,47]. It is found that the decrease in the phonon group velocities is less than 5.5% of that of the bulk values of the samples, this is because of the relatively large diameter of the samples.…”

“…It is found that the decrease in the phonon group velocities is less than 5.5% of that of the bulk values of the samples, this is because of the relatively large diameter of the samples. The decrease in the phonon group velocity is significant for nanowires of diameter less than 100nm (called a small diameter in this work) [44][45][46]. So, the phonon group velocities of bulk Si and Ge (as shown in Table 1) were used (using Eq.…”