Studies On Thermodynamic Properties And Quantum Effects Of Small Semiconductor Particles

Nanotechnology is a frontier science in the world. Now, nanoscience continues to advance at a dramatic pace and is making revolutionary contributions in diverse fields, including electronics, optoelectronics, quantum electronics, materials science, chemistry, and biology. The technologies needed to fabricate nanoscale structures and devices are advancing rapidly. These technologies have made possible the design and study of a vast array of novel devices, structures and systems confined dimensionally on the scale of 10 nanometers or less in one or more dimensions. Moreover, nanotechnology is continuing to mature rapidly and will, no doubt, lead to further revolutionary breakthroughs like those exemplified by quantum-dot semiconductor lasers operating at room temperature, intersubband multiple quantum-well semiconductor lasers, quantum-wire semiconductor lasers, double-barrier quantum-well diodes operating in the terahertz frequency range, single-electron transistors, single-electron metal-oxide-semiconductor memories operating at room temperature, transistors based on carbon nanotubes, and semiconductor nanocrystals used for fluorescent biological labels, just to name a few!In this thesis, Green's function and Media theory is applied to study the thermodynamic properties in a nanoparticles, which is weakly coupled to a substrate. The research benefits ours understanding the phenomena observed and provides theoretical guidance on fabricating nanoscale devices.In the first part, we introduce the Green's function and elastic theory. Elastic theory previously used primarily for studying the solid. In the long-wave approximation, nanoparticle can be regarded as an elastic body, so elastic theory can be used to work out all eigenvectors and eigenmodes in the nanoparticle under the free boundary conditions.In the second part, we obtain phonon spectrum in nanoparticle under the perturbation effect by solving phonon Dyson equation. Furthermore, we solve out the thermodynamic properties of this nanoparticle by numerical calculation. We find that the substrate provides low frequency phonons instead of absorbing the phonons from the nanoparticle.