ABSTRACT

The objective of the present work is divided into two main parts. In the first part, the theoretical calculations are performed on lattice thermal conductivity (LTC) and corresponding parameters for the zinc blende and wurtzite structure of InAs nanowires (NWs) with diameters of 50, 63, 66, 100, and 148 nm through the Debye–Callaway model. In order for the model to be efficiently applicable, both longitudinal and transverse modes are considered. The melting point of the various-sized NWs is considered to estimate the Debye and phonon group velocities. The impacts of the Gruneisen parameter, dislocations, and surface roughness have also been successfully utilized to address the calculated and measured LTC of the semiconductor under investigation. Results show that the Gruneisen parameter increased with the decrease of NWs diameter and that phonon confinement leads to an observable deviation of the calculated LTC curve from that of the experimental one in the case of bulk InAs. It has been assumed that nanowire boundaries, dislocations, and imperfections are responsible for scattering of phonons and electrons due to both normal and Umklapp processes. Therefore, at a specified temperature, LTC depends on the crystal size and structure of the semiconductor. As a result of the quantum confinement effect, the thermal and mechanical parameters of InAs are greatly modified by decreasing the size as well as dimensions of the semiconductor.

In the second part, the Debye–Callaway model was used to calculate the lattice thermal conductivity (LTC) of indium arsenide in both zinc-blende and wurtzite phases for both bulk and nanowire (NW) forms and under various applied hydrostatic pressures. Calculations were performed for NWs with different diameters in the temperature range of 0–400 K. The melting temperature and hydrostatic pressure phase diagram of the bulk and NW X forms were predicted using the Clapeyron equation. Then, a new method was developed to examine various related parameters, such as bulk modulus and mass density. However, besides the influence of pressure on melting temperature, melting enthalpy, melting entropy surface energy, and stress were also determined. Results indicate that the calculated values of the group velocity increased with the increase in NW size.
Additionally, the melting temperature dropped sharply with the rise in the pressure. The pressure and temperature dependencies of LTC were systematically obtained, and the maximum value of LTC decreases with the increase of hydrostatic pressure for both bulk and the corresponding
nanowires.